Document:

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                                                                   EXHIBIT 10.13

                               SUPPLY AGREEMENT
                                  No. C000325

                                      FOR

                      MANUFACTURING AND RELATED SERVICES

                                    Between

                             SOLECTRON CORPORATION

                                      And

                           ZHONE TECHNOLOGIES, INC.
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                               SUPPLY AGREEMENT
                                 No.  C000325

This Supply Agreement ("Agreement") is entered into by and between Solectron
Corporation, located at 847 Gibraltar Drive, Milpitas, CA  95035, by and on
behalf of its subsidiaries and affiliates ("Solectron") and Zhone Technologies,
Inc., located at 7677 Oakport Street, Suite 1040, Oakland, CA 94621, by and on
behalf of its subsidiaries and affiliates ("Zhone").

1.0  Agreement Structure

1.1  This Agreement shall become effective concurrently with the date of
     execution of the Asset Purchase Agreement ("Effective Date").

1.2  This Agreement consists of: (i) this base Supply Agreement which defines
     the basic terms and conditions of the relationship between the parties;
     (ii) Statements of Work; and (iii) the following Exhibits, which detail
     among other things specific information regarding work performed under this
     Agreement

          Exhibit A-1 - Products
          Exhibit B-1 - Pricing Model
          Exhibit C-1 - Flexibility/Cancellation/Component Liability
          Exhibit D - Out of Warranty Services
          Exhibit E - Commodity Substitution Approval Form

1.3  If there is a conflict among the terms and conditions of the various
     documents or an ambiguity created by differences between them, the order of
     decreasing precedence shall be (i) Statements of Work, (ii) Exhibits, and
     (iii) Supply Agreement.

2.0  Definitions

     "Asset Purchase Agreement" shall mean that certain Asset Purchase Agreement
     dated March 13, 2000, between Solectron Texas, L.P. and Premisys
     Communications, Inc.

     "Components" shall mean any parts, material, components, or other items
     that are used in the manufacture and assembly of Products.

     "Engineering Change" or "EC" shall mean any electrical or mechanical
     change(s) to a Product which would affect the function, performance,
     programming model, reliability, safety, serviceability, appearance,
     dimensions, tolerances, or composition of bills of material, or material
     sources thereof.

     "Engineering Support Services" means those services described in Section
     5.3.

     "Excess Components" means Components in Solectron's inventory that were
     purchased within agreed to material order Lead Times and in quantities to
     support Zhone's demand forecast, which
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     are non-cancelable and/or non-returnable and for which the latest demand
     forecast does not show consumption in any Product within the next ninety
     (90) days.

     "Final Premium Amount" has the meaning specified in Section 2.5 of the
     Asset Purchase Agreement.

     "Lead Time" means (i) with respect to Components, the minimum length of
     time prior to a specific delivery date that Solectron must issue a purchase
     order for Components to ensure delivery by such date; and (ii) with respect
     to Products, the minimum length of time prior to a specific delivery date
     that Solectron must receive an order from Zhone to ensure manufacture and
     delivery by such date.

     "Manufacturing Design" means any Work Product or any other material,
     including mechanical design elements in support of the manufacturing
     process, that relate to manufacturing equipment, manufacturing processes
     and/or the manufacturability of Products (i.e. DFX).

     "Manufacturing Services" means those services described in Section 5.2.

     "Material Breach" means those events of breach set forth in Section 16.1.

     "No Defect Found" or "NDF" shall mean a Product whose function was suspect,
     but no specific fault was detected in Solectron's performance of failure
     analysis.

     "Obsolete Components" means Components in Solectron's inventory that were
     purchased within agreed to material order Lead Times and in quantities to
     support Zhone's demand forecast, which are non-cancelable and/or non-
     returnable and for which the latest demand forecast does not show
     consumption in any Product within the next one-hundred eighty (180) days.

     "Order" shall have the meaning specified in Section 6.4.

     "Pre-existing Work Product" means Work Product created or owned (as between
     Solectron and Zhone) by one party prior to the date of this Agreement.

     "Pre-Production Services" means those services described in Section 5.1.

     "Product(s)" means the completed assemblies manufactured by Solectron and
     also includes any field replaceable units, specific components of a field
     replaceable unit, subassemblies of a field replaceable unit, service Parts,
     documentation, code and related Services associated with the completed
     assemblies as specified in the Exhibits.  Products shall not include
     Prototypes.  The initial Products covered by this Agreement are set forth
     on Exhibit A-1 ("Initial Products").  The parties may add or delete
     Products from this Agreement only by mutual agreement.  Any Products added
     will be set forth in additional Exhibits (e.g., Exhibit A-2, Exhibit A-3,
     etc.) signed by both parties ("Follow-on Products").  In lieu of a separate
     Product Exhibit, the parties may agree to add Products via quotations
     against which Orders are placed.  The term Products shall mean only Initial
     Products and any Follow-on Products, only if applicable.

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     "Product Design" means any Work Product or any other material, including
     electrical, mechanical, industrial, circuit and/or schematic design
     elements, and Product Specifications, that relate to the functional design
     of the Products.

     "Prototype" means a preliminary version of a Product which may or may not
     be functional, is intended for internal use and testing and not for resale,
     and is not suitable for production in commercial quantities.

     "RMA" means returned material authorization.

     "Return" means an amount equal to the product of the Final Premium Amount
     times 1.333.

     "Services" shall mean the pre-production, manufacturing, testing,
     engineering, and other related services described in this Agreement,
     applicable Exhibits, and Statements of Work.

     "Statement(s) of Work" shall mean documents agreed to in writing by both
     parties, which describe the work to be performed, the pricing for such
     work, the specifications and any supplemental terms that additionally apply
     to such work.  In the absence of such separate document(s), Solectron's
     quotation(s) against which Zhone's orders are submitted and accepted will
     constitute the Statement(s) of Work.  This Agreement may include multiple
     Statements of Work.

     "Specifications" shall mean that portion of each Statement of Work that
     provides objective, physical specifications for work to be performed.
     Solectron will purchase and assemble material according to such
     specifications. The Commodity Substitution Approval Forms attached hereto
     and incorporated herein (Attachment B) shall be considered part of Zhone's
     specifications.

     "Test Design" means any Work Product or other material, including test
     development, programming, or processes, related to testing a Product.

     "Tooling" means equipment, fixtures, tools, testers, code and other similar
     items used in performance of this Agreement.

     "WIP" means work-in-process and relates to partially completed Products in
     Solectron's manufacturing process.

     "Work Product" means (a) any net list, schematic, diagram, circuitry,
     technology, invention, idea, discovery, improvement, design, concept,
     technique, algorithm, formula, method, process, configuration, mechanism,
     model, system, network, data, plan, library, work of authorship, file,
     media, record, report, copy, pictorial work, graphic work, audiovisual
     work, hardware, firmware, computer interface (including for example but not
     limited to programming interfaces), computer language, computer protocol,
     computer software program or application (irrespective of whether source
     code or object code), flow chart, blueprint, drawing, graph, information,
     material, research or development, irrespective of whether patentable, or
     (b) any portion, copy or extract of such Work

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     Product, irrespective of whether in tangible or intangible form, and
     irrespective of the media of such Work Product.

3.0  Term

3.1  Except as provided by Section 16.0, this Agreement shall be effective on
     the Effective Date and shall remain in force for (i) the Initial Products
     for four (4) years, and (ii) any Follow-on Products until such time as the
     parties execute a separate, definitive agreement covering those Products
     (the "Initial Term"). Following the Initial Term, this Agreement shall
     automatically be renewed for one (1) year. Thereafter, this Agreement shall
     automatically be renewed for successive one (1) year increments unless
     either party requests in writing, at least ninety (90) days prior to the
     anniversary date, that this Agreement not be so renewed. The parties
     acknowledge the need to better understand the business model for, and
     appropriate terms that should apply to, Follow-on Products and the parties
     will endeavor to negotiate a separate agreement to address these Products.

4.0  Purchase Commitment and Prices

4.1  During the Initial Term and subject to the limitations set forth herein,
     Solectron shall supply and Zhone shall purchase Initial Products and
     related Manufacturing Services exclusively from Solectron.

4.2  The pricing model for the Initial Products is set forth in Exhibit B-1,
     which may be changed by mutual agreement of the parties by executing a new
     pricing model.  The pricing model for Follow-on Products will be set forth
     in an additional Exhibit(s) that corresponds to the applicable Product
     Exhibit (e.g., Exhibit B-1, B-2, etc.) which is signed by both parties, or
     in a quotation against which Orders are placed.  During the Initial Term of
     this Agreement, the prices for Initial Products (and any other mutually
     agreed Products) will include a five percent (5%) mark-up over the agreed
     base pricing model to enable Solectron to recover the Return.  During the
     Initial Term of this Agreement, the parties agree to meet on each
     anniversary of the Effective Date to review the status of Solectron's
     recovery of the Return.  If Solectron recovers the Return prior to the
     expiration of the Initial Term of this Agreement, then the prices then in
     effect will be reduced by the five percent (5%) mark-up.  At each review,
     if the revenue stream from the Products is not achieving an annual run-rate
     that is consistent with recovery of the Return during the Initial Term of
     this Agreement, then within thirty (30) days of said review, Zhone will
     make a payment to Solectron equal to that portion of the Return on a pro-
     rated basis that has not been recovered at the time of the review.  The
     parties further agree that if Solectron has not recovered the Return by the
     expiration of the Initial Term of this Agreement, then within thirty (30)
     days of the expiration of the Initial Term of this Agreement, Zhone will
     make a payment to Solectron equal to that portion of the Return that has
     not been recovered by Solectron.

4.3  In the event that Zhone rightfully terminates this Supply Agreement in
     accordance with Section 16.1 for Solectron's Material Breach, Zhone's
     purchase commitment contained in Section 4.1 above and Zhone's guarantee
     that Solectron shall receive the Return contained in Section 4.2 above will
     be terminated without further obligation to Solectron.

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4.4  Prices for Pre-Production, Engineering Support Services, Out-of-Warranty
     Service, and all other services will be mutually agreed to by the parties.

4.5  The parties acknowledge and agree to meet quarterly to review the Product
     prices for the purpose of reducing the Product prices for the upcoming
     quarter. Each party shall diligently pursue cost improvement opportunities
     for each and every element of the price to reduce the cost of the Products,
     including but not limited to, recommending design or process changes, and
     new sources, which may result in an overall cost reduction. The parties
     acknowledge and agree that the Price for any particular Product may be
     increased to the extent of any price increase of any Component incorporated
     into such Product or any increases in assembly or test time due to any
     Engineering Change order or specific instructions from Zhone. Any price
     change shall apply only to purchase orders or material releases issued
     after the effective date of such price change.

5.0  Products, Services and Systems

5.1  Pre-Production Services.

     (i)  Solectron shall provide Pre-Production Services to Zhone as agreed
     upon by the parties. The specific scope of Pre-production Services will be
     specified in the Statement of Work applicable to the Product, and may
     include, without limitation, the following:

          A.  design for manufacturing and test evaluations
          B.  development of assembly and test processes
          C.  development of test programs and/or fixtures
          D.  production of prototype and/or validation units

     (ii) Solectron will perform such Pre-Production Services and deliver any
     pre-production deliverables to Zhone in accordance with the pre-production
     schedule and accepted order(s) applicable to such Pre-Production
     Deliverables. If Zhone requires Solectron to produce prototype builds,
     Solectron will:

          A.   deliver each such build within five (5) days of commencing
               production of the prototype build provided Solectron has all
               necessary material, documentation, tools, fixtures and equipment;
          B.   deliver a DFM report to Zhone within five (5) days after
               delivering a prototype build to Zhone.

     (iii) Solectron shall operate a prototype facility dedicated to production
     of pre-production deliverables in such a manner as to ensure that the
     prototype build activity will not hinder Solectron's manufacturing
     capability to meet Zhone's Product demand requirements and vice versa.

     (iv) The parties shall agree in writing upon pricing for prototype and
     pilot builds.  Costs for other services will be handled in accordance with
     the provisions of Section 5.3 below.

     (v) Test Engineering. Zhone will provide Solectron with test vectors and
     all other information reasonably necessary to develop test programs and
     fixtures for the Products. Solectron will designate a test engineer(s), as
     Zhone deems necessary and as mutually agreed, who shall be responsible for
     interacting with Zhone's test engineering group in a timely manner to
     develop and/or support (as specified in the relevant Product plan) test
     programs and test fixtures for use in manufacturing such Product for Zhone.
     Upon mutual agreement by the parties, Solectron will locate such test
     engineer(s) at Zhone's engineering facilities.

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     (vi)   Pre-Production Reports and Reviews.  Prior to the award of any pre-
     production program by Zhone, Solectron shall provide Zhone with a project
     plan which includes a detailed timeline with milestones. Upon award of any
     pre-production program by Zhone the parties will mutually agree upon the
     detailed project plan. During the pre-production program, Solectron will
     provide Zhone with regular written progress reports at least monthly. All
     such reports shall include, but shall not be limited to, the following: (A)
     status of progress toward milestones; (B) short description of problems or
     potential problems, if any, preventing Solectron from meeting the
     milestones; (C) recovery method proposed in order to meet milestones, if
     needed, and (D) any other information related to the pre-production
     Services as reasonably requested by Zhone.

     (vii) Zhone shall have the right to conduct periodic reviews of Solectron's
     Pre-Production  Services.  Upon  reasonable  notice,  Solectron  will allow
     Zhone, during Solectron's normal business hours, to visit those portions of
     Solectron's  facilities  used to perform  such  pre-production  Services to
     inspect and discuss the status of pre-production activities.

5.2  Manufacturing Services.  Solectron will accept any Orders for Products
issued in accordance with this Agreement.  Solectron agrees to manufacture,
test, package and deliver the Product quantities committed in accordance with
the Specifications and Quality Plan for such Products and deliver such
quantities to Zhone or its customers, pursuant to the terms of this Agreement.

5.3  Engineering Support Services. Solectron shall provide Engineering Support
Services which shall include, without limitation, the following:

          A. Designated  Component  Engineering liaison to interact with Zhone's
          designers.  Such  liaison  will,  among  other  things,  assist in the
          selection of Components  meeting  design  requirements  and coordinate
          Component  evaluations  and  qualifications.
          B. Support Zhone's quick turn prototype requirements.
          C.  Perform  Beta  Pilot  production  checkout.
          D. Provide  seamless  transfer  from  prototype/pilot  environment  to
          Solectron's volume production sites.

     Such services will be provided at mutually agreed pricing and, except as
     provided otherwise herein, billed in the period supplied.  Designated
     resources will be billed on a monthly basis.

5.4  Out-of-Warranty Service.  Solectron shall provide Out-of-Warranty Service
to Zhone under terms and conditions substantially similar to the form attached
as Exhibit D.

5.5  Failure Analysis, Repair and Refurbishment. Solectron shall provide failure
     analysis, repair and refurbishment services to Zhone for both in-warranty
     and out-of-warranty Products as set forth in Section 15.2 and Exhibit D,
     respectively.

5.6. Program Management.  Each party shall designate a manager authorized to
     act as  its worldwide single point of contact for all business and
     strategic issues pertaining to this Agreement. In addition, Solectron shall
     designate a program manager(s), who may be physically located at Zhone's
     facility, to act as Solectron's single point of contact with Zhone in
     connection with each new Product release to be manufactured by Solectron
     hereunder.  The parties shall agree upon in writing the scope of the
     program manager's responsibilities during the Product life cycle. Solectron
     shall implement a

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     dedicated "customer focus team", consisting of (at least) one (1) program
     manager, one (1) materials manager and one (1) technical manager. The
     responsibility of the customer focus team shall be to manage Solectron's
     performance hereunder.

5.7  Tooling and NRE.  The Parties acknowledge and agree that Solectron may
     incur non-recurring expenditures for Tooling, software programs and other
     expenses for the manufacture of the Products.  All such non-recurring
     expenditures will be agreed upon in writing by Zhone and Solectron prior to
     incurrence and be the subject of separate purchase orders which will be
     independent of any Orders for Products.  Solectron will invoice Zhone for
     such approved expenditures and such invoices will be paid by Zhone within
     ten (10) days of the date of the invoice.  Unless otherwise agreed in
     writing by the parties, Tooling will be furnished and owned solely by Zhone
     and consigned to Solectron, or purchased or manufactured by Solectron and
     paid for by Zhone.  Solectron shall bear the cost of maintaining Tooling;
     provided, however, that Zhone will bear the cost of repairing or replacing
     Tooling that becomes obsolete or experiences significant defects or quality
     problems. All Zhone Tooling/equipment furnished to Solectron or paid for by
     Zhone in connection with this Agreement shall: (i) be clearly marked and
     remain the personal property of Zhone; and (ii) be kept free of liens and
     encumbrances.  Solectron shall hold Zhone property at its own risk and
     shall not modify the property without the written permission of Zhone. Upon
     Zhone's request, Solectron shall redeliver the property to Zhone in the
     same condition as originally received by Solectron with the exception of
     reasonable wear and tear. In the event the property is lost, damaged or
     destroyed, Solectron's liability for the property is limited to the book
     value of the property.

5.8  Systems.  Zhone and Solectron agree that Zhone's order management and
     fulfillment system will be installed at Solectron on or before the
     Effective Date of this Agreement.  Zhone is responsible for maintaining
     this system and will provide all resources and pay for all costs associated
     with such maintenance.  Solectron will have a license to access and use
     this system for the purpose of performing its obligations under this
     Agreement.

6.0  Material Procurement, Orders

6.1  Solectron will procure Components only from Zhone's authorized vendors.
     Zhone will provide Solectron with an approved vendor list for each phase of
     Product manufacture.  Solectron will not procure Components from alternate
     vendors nor deviate from the approved vendor list without prior written
     approval or as provided in Exhibit E.  Solectron may, from time to time,
     suggest its preferred suppliers as alternate vendors to Zhone and Zhone
     agrees to use reasonable commercial efforts to evaluate and approve
     Solectron's preferred suppliers for addition to the approved vendor list.

6.2  Zhone will provide Solectron a rolling six (6) month Product forecast. The
     most recent three (3) months of such forecast will reflect weekly Product
     demand and such portion of the forecast will be updated weekly via the
     order management and fulfillment system. In addition, during the first
     month of the current calendar quarter, Zhone will provide Solectron with a
     quarterly blanket purchase order for the following calendar quarter, which
     will be refreshed at least once every thirty

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     (30) days. Such forecast and blanket purchase order will not be binding on
     Zhone and do not represent a commitment to purchase Products except as
     otherwise set forth in this Agreement.

6.3  Solectron is authorized to purchase Components to support Zhone's blanket
     purchase order and forecast pursuant to Component Lead Times and consistent
     with standard purchasing practices including, but not limited to,
     acquisition of economic and minimum order quantities. Zhone recognizes its
     financial responsibility for the Components purchased by Solectron on
     behalf of Zhone in accordance with this provision to the extent such items
     are non-cancelable and/or non-returnable.

6.4  For the Initial Products and any other mutually agreed Products, Solectron
     will utilize Zhone's order management and fulfillment system to monitor and
     respond to Zhone's actual Product demand. Zhone's receipt of a customer
     order in its order management and fulfillment system is Solectron's
     authorization to manufacture and ship Product and Zhone's commitment to buy
     Product in the quantities specified in the customer order (an "Order") or
     as otherwise committed by Solectron pursuant to Sections 7.0 and 8.0. In
     all other cases, Zhone will issue purchase orders or material releases
     against a blanket purchase order (also an "Order"). Solectron will notify
     Zhone of its acceptance or rejection of the Order within five (5) business
     days of receipt. Rejections, if any, will be based on the quantities
     requested as compared to those previously forecasted. In the event that
     Solectron does not notify Zhone of its acceptance or rejection, then such
     Order will be deemed accepted. Accepted Orders will constitute Zhone's
     authorization for Solectron to manufacture and ship Product to Zhone in the
     quantities agreed.

6.5  In the event of a decrease in Zhone's forecast or blanket purchase order
     quantity, reschedule or cancellation of an Order, discontinuance of
     Product, or an engineering change, Zhone agrees to compensate Solectron for
     Excess Components in accordance with Section 10.1 below.

6.6  Solectron shall undertake all commercially reasonable efforts to cancel all
     applicable Component purchase orders and reduce Component inventory through
     return for credit programs or allocate Components for alternate programs if
     applicable.

7.0  Delivery

7.1  Solectron will use all commercially reasonable efforts to achieve 100% on
     time delivery, defined as shipment of Product by Solectron within a window
     of three (3) days early and zero days late of the committed delivery date.
     Upon learning of any potential delivery delays, Solectron will notify Zhone
     as to the cause of such delays and the actions taken by Solectron to
     resolve such delays.  Solectron's Lead Time for Orders received with
     quantities that are equal to or less than those specified in the most
     recent weekly forecast is ten (10) days unless Zhone is notified otherwise
     in writing by Solectron at least thirty (30) days prior to receipt of the
     Order.  For any Orders received with materially different quantities or a
     shorter Lead Time, Solectron will notify Zhone of the committed delivery
     date.

7.2  All U.S. origin shipments by Solectron are F.O.B. Solectron's point of
     shipment (i.e., at Solectron's manufacturing plant).  All other shipments
     are Ex Works-Solectron's point of shipment (i.e., at

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     Solectron's manufacturing plant). Title to Product(s) and risk of loss will
     pass to Zhone upon Zhone's or its agent's retrieval of Product(s) at
     Solectron's point of shipment.

7.3  Zhone shall have a reasonable time to inspect the Products.  Zhone will
     notify Solectron in writing of particular deficiencies during the
     inspection period which shall be the ten (10) day period immediately
     following receipt.  Failure to give notice of or particularize the
     deficiencies will constitute Zhone's acceptance.

7.4  If applicable, Solectron shall provide Zhone with a valid, accurate
     completed Exporter's Certificate of Origin for all Products which qualify
     for preferential duty treatment under the North American Free Trade
     Agreement ("NAFTA"). Solectron shall deliver the Exporter's Certificate of
     Origin to Zhone prior to the first shipment of such Products in order to
     enable Zhone to claim preferential duty treatment under NAFTA at the time
     of entry. Solectron shall notify Zhone in writing prior to making any
     pricing or sourcing changes that might result in the Products being deemed
     ineligible for preferential duty treatment under NAFTA. Solectron
     recognizes that the Exporter's Certificate of Origin will be used by Zhone
     as proof of eligibility for preferential duty treatment and agrees to
     provide full cooperation to Zhone in connection with any U.S. Customs
     inquiries into NAFTA claims relating to this Agreement.

7.5  Zhone reserves the right to claim duty drawback on all purchases from
     Solectron, and Solectron shall cooperate by providing the necessary
     certificates of Delivery or in instances where the imported Product
     received further processing, shall furnish certificates of manufacture and
     delivery on all articles and Products which may be subject to drawback as
     requested by Zhone.

8.0  Flexibility of Shipments

     The parties may agree to different flexibility terms that will apply to
     specific Products by executing a Flexibility/Cancellation/Component
     Liability Terms Exhibit C that corresponds to the applicable Product
     Exhibit (e.g., Exhibit C-1, C-2, etc.)  In the absence of such different
     terms, the following flexibility terms will apply to any effective Product
     Exhibits.

8.1  Request to Accelerate Delivery.  Zhone may request acceleration of delivery
     -------------------------------
     of Products by issuing an electronic or written (including facsimile)
     notice to Solectron, or by increasing its forecasted Product demand in the
     order management and fulfillment system.  Solectron will use all
     commercially reasonable efforts to accept the requested new delivery date.
     Solectron will notify Zhone of and seek Zhone's prior written agreement to
     reasonable and actual premium costs, if any, required to meet the requested
     accelerated delivery date. Zhone will have the option of accepting these
     premium charges or maintaining the original delivery date.

8.2  Confirmation and Acceptance of Request to Change Product Mix or Accelerate
     --------------------------------------------------------------------------
     Delivery.  Solectron agrees to give electronic or written (including
     ---------
     facsimile) confirmation of receipt of Zhone's request within five (5)
     business days.  Zhone's request shall be deemed accepted by Solectron if
     Zhone does not receive Solectron's electronic or written (including
     facsimile) acceptance or rejection within five (5) business days after
     receipt of Zhone's request.

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8.4  Request to Delay Delivery
     -------------------------
 (i) Zhone may reschedule individual shipments of Product. Solectron will
     use reasonable efforts to accommodate such requests on a case-by-case
     basis. Such reschedules may be subject to additional charges and will be
     contingent upon availability of material, personnel and capacity resources.
     If the requested rescheduled delivery date is more than ninety (90) days
     after the original scheduled delivery date, the affected inventory may be
     deemed Excess Components, and the terms of Section 10.1 will apply. Such
     charges shall be reviewed and approved by Customer prior to the reschedule
     being executed. Any rescheduled item may be invoiced at the price in effect
     at the time of shipment.

     (ii) Zhone will notify Solectron of its request by issuing an electronic or
     written (including facsimile) notice to Solectron, or by decreasing its
     forecasted Product demand in the order management and fulfillment system.
     Solectron will respond to Zhone's request to delay delivery of Product
     demand within five (5) business days from the receipt of Zhone's request.
     If Zhone does not receive Solectron's written (including facsimile) or
     electronic response within five (5) business days after receipt of Zhone's
     request, then Zhone's request shall be deemed accepted by Solectron.

9.0  Cancellation of Shipments

     The parties may agree to different cancellation terms that will apply to
     specific Products by executing a Flexibility/Cancellation/Component
     Liability Terms Exhibit C that corresponds to the applicable Product
     Exhibit (e.g., Exhibit C-1, C-2, etc.)  In the absence of such specific
     terms, the following cancellation terms will apply to any effective Product
     Exhibits.

9.1  Zhone's requests to cancel shipments of Products will be reviewed
     individually by Solectron.  Cancellation charges will be assessed as
     follows: (a) for shipments scheduled to ship within forty five (45) days,
     cancellation charges shall be 100% of the price of the Products being
     canceled; (b) for shipments scheduled beyond forty five (45) days,
     cancellation charges will include: (i) the contract price of all finished
     Products in Solectron's possession, (ii) the cost of work-in-process
     inventory (including handling charges and value add), (iii) the cost of
     Components on order (including handling charges) or on hand which cannot be
     canceled or returned to the vendor pursuant to the terms of Section 10.1
     below, (iv) any vendor cancellation charges incurred with respect to
     material canceled or returned to the vendor, (v) material handling charges,
     and (vi) charges for non-recurring services associated with work stoppage.
     Charges will be based on the date written notice of a cancellation is
     received at Solectron.

9.2  Where cancellation of a previously rescheduled shipment has occurred, the
     cancellation charge may be computed as if the previously requested
     reschedule had instead been a request for cancellation.

9.3  Orders for Tooling, test equipment or non-recurring services are firm and
     not cancelable.

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<PAGE>

10.0 Excess and Obsolete Components

     The parties may agree to different Component liability terms that will
     apply to specific Products by executing a
     Flexibility/Cancellation/Component Liability Terms Exhibit C that
     corresponds to the applicable Product Exhibit (e.g., Exhibit C-1, C-2,
     etc.) In the absence of such different terms, the following Component
     liability terms will apply to any effective Product Exhibits.

10.1 If Zhone cancels or reschedules Orders, changes its forecast, fails to
     receive customer orders in its order fulfillment and management system, or
     implements an Engineering Change notice, or breaches this Agreement (such
     actions shall collectively be referred to as a "Material Event"), which
     results in Excess and/or Obsolete Components (including long lead material,
     MOQ's, and unique/custom material), then if those Excess and/or Obsolete
     Components are not fully consumed prior to the end of sixty (60) days
     following the date of the Material Event, Solectron may request and Zhone
     agrees to pay Solectron a carrying charge on the inventory of two percent
     (2%) per month. Zhone agrees to pay such carrying charge on such Excess
     and/or Obsolete Components until it is fully consumed; provided, however,
     that if it is not consumed by the end of the ninety (90) days following the
     date of the Material Event, Solectron may request and Zhone shall purchase
     such Excess and/or Obsolete Components from Solectron and Solectron will
     continue, at Zhone's option, to hold such inventory on Zhone's behalf,
     subject to agreed carrying charges, or Solectron will deliver the
     Components to Zhone's designated location at Zhone's expense. Solectron
     will use all commercially reasonable efforts to minimize the Excess and/or
     Obsolete Components.

11.0 Invoice and Payment Terms

11.1 Solectron will invoice Zhone upon shipment of Product. Solectron and Zhone
     agree to payment terms of net ten (10) days from the date of invoice or
     delivery of Product, whichever occurs later. If Zhone fails to make timely
     payment or satisfy credit arrangements, it shall be deemed a Material
     Breach of this Agreement as more fully set forth in Section 16.1. In this
     event, Solectron may, in addition to any other rights and remedies provided
     at law or in equity, suspend its performance under this Agreement and
     withhold shipment of Products, refuse to accept further orders, change
     credit and payment terms, request other assurances and/or take any other
     action that Solectron, in its sole discretion, deems appropriate until
     Zhone makes other arrangements satisfactory to Solectron. In the event
     Zhone does not cure the Material Breach or make alternative arrangements
     satisfactory to Solectron, Solectron may terminate this Agreement and
     exercise any and all rights and remedies provided at law or in equity or in
     this Agreement, including this Section 11.1.

11.2 Currency will be in U.S. Dollars unless specifically negotiated otherwise
     and reflected in a Statement of Work.

11.3 Except for the net value added taxes, prices are exclusive of all taxes,
     duties, customs or similar charges and are subject to an increase equal in
     amount to any charge Solectron may be required to collect or pay upon
     shipment of the Product.

12.0  Quality

                                       11
<PAGE>

12.1 Zhone shall for each Product provide an initial proposed quality plan which
     sets forth, without limitation, the operation flow of each Product, the
     process control for each Product, the audit procedures for each Product and
     the inspection procedures for each Product. Solectron shall have the
     opportunity to review and provide comments on such plans. A final plan will
     be mutually agreed to in writing (the "Quality Plan") Any changes to the
     plans will be mutually agreed in writing.

12.2 Upon reasonable notice and during normal business hours, Zhone shall have
     the right to review, inspect, test and evaluate Solectron's facilities,
     operations, manufacturing and test processes, and procedures that relate to
     Solectron's performance of this Agreement for the purposes of determining
     compliance with this Agreement and quality control.

13.0 Engineering Changes

13.1 Zhone may submit Engineering Changes to Solectron in writing for
     incorporation into the Product. It is important that this notification
     include documentation of the change to effectively support an investigation
     of the impact of the Engineering Change. Solectron will use all
     commercially reasonable efforts to review the Engineering Change and
     respond to Zhone within one (1) week. If any such change affects the price,
     delivery, or quality performance of said Product, an equitable adjustment
     will be negotiated between Solectron and Zhone prior to implementation of
     the change. In the event Zhone requests that a change be implemented prior
     to Solectron's evaluation of pricing and schedule impact, Solectron will
     use all commercially reasonable efforts to perform as directed and Zhone
     will be liable for all costs associated with such implementation. The terms
     of Section 10.1 shall apply to any Excess or Obsolete Components that
     result from an Engineering Change.

13.2 Solectron agrees not to undertake significant process changes, product
     design changes, or process step discontinuance affecting electrical
     performance and/or mechanical form, fit and function without prior written
     notification and concurrence of Zhone.

14.0 Confidential Information

14.1 All proprietary and confidential information exchanged between the parties
     in connection with this Agreement shall be subject to the terms of that
     certain Nondisclosure Agreement, dated March 13, 2000, between Solectron
     and Zhone attached as Exhibit A to the Asset Purchase Agreement. Such
     Nondisclosure Agreement shall be deemed to run concurrently with the term
     of this Agreement.

14.2 Subject to the terms of the Nondisclosure Agreement and the proprietary
     rights of the parties, Solectron and Zhone agree to exchange, at least
     semi-annually, relevant process development information and business plans
     to include market trends, process technologies, product requirements, new
     product developments, available capacity and other information to support
     technology advancements by both Solectron and Zhone.

15.0 Warranty

                                       12
<PAGE>

15.1 The parties intend to collect data for one hundred eighty (180) days with
     the goal of agreeing to a warranty period of eighteen (18) months from the
     date of shipment. Until a separate agreement in writing is reached, and
     unless otherwise agreed in a Product Exhibit, Solectron warrants for a
     period of twelve (12) months from the date of manufacture of the Product
     that (i) the Product will conform to the specifications applicable to such
     Product at the time of its manufacture, which are furnished in writing by
     Zhone and accepted by Solectron; and (ii) such Product will be of good
     material (supplied by Solectron) and be free from defects in workmanship.
     If Products are subject to a third-party manufacturers' warranty, then to
     the extent permitted by such third-party, Solectron hereby assigns such
     warranties to Zhone.

15.2 ZHONE'S SOLE AND EXCLUSIVE REMEDY AND SOLECTRON'S ENTIRE LIABILITY FOR
     BREACH OF WARRANTY IS AS STATED IN THIS SECTION 15.2. In the event that any
     Product manufactured shall not be in conformity with the foregoing
     warranties, Solectron shall, at Solectron's option, either credit Zhone for
     any such nonconformity (not to exceed the purchase price paid by Zhone for
     such Product), or, at Solectron's expense, replace, repair or correct such
     Product. Repaired or replaced Product shall be warranted for the remainder
     of the original warranty period or ninety (90) days, whichever is greater.
     Zhone agrees to pay a screening fee for assemblies submitted for warranty
     work that are not packed appropriately, result in No Defect Found, or are
     required to be tested against a later version test software than was used
     at the time of manufacture. Such fee will be negotiated and established in
     good faith by the parties based on historical field data and other relevant
     information. Zhone will cover all transportation costs to and from
     Solectron for warranty repairs and shall retain title to returned Product.

15.3 Solectron shall have no liability or responsibility for any costs, losses
     or damages due to defective or failed Product claims to the extent that the
     claims result from: (a) Solectron's compliance with Zhone's supplied
     Specifications and/or manufacturing processes, (b) inadequate operating
     environment, accident, disaster, neglect, abuse, or misuse, (c) design
     flaws or design parameters exceeding or violating component specifications,
     (d) external or environmental factors after shipment from Solectron, (e)
     follow-on handling, processing, or manufacturing of Products after shipment
     of the Product from Solectron or the SLC, as applicable, (f) repair,
     attempted repair, modification, or alteration of the Product by a party
     other than Solectron, (g) electrostatic discharge damage (not caused by
     Solectron), (h) defects related to components provided by third party
     suppliers selected by Zhone, which defects Solectron could not reasonably
     detect, prevent or control, and (i) Products for which Zhone has not
     provided functional or other tests to adequately diagnose failures.

     Solectron makes NO WARRANTY as to software which is supplied on an "AS IS"
     basis.  Likewise, Solectron makes NO WARRANTY as to prototypes, pre-
     production units, or units shipped at Zhone's request with less than the
     testing provided for in the work order for production units.

15.4 THE WARRANTIES CONTAINED IN THIS SECTION ARE IN LIEU OF, AND SOLECTRON
     EXPRESSLY DISCLAIMS AND ZHONE WAIVES ALL OTHER REPRESENTATIONS AND
     WARRANTIES, EXPRESS, IMPLIED, STATUTORY OR ARISING BY COURSE OF DEALING OR
     PERFORMANCE, CUSTOM, USAGE IN THE TRADE OR OTHERWISE,

                                       13
<PAGE>

     INCLUDING WITHOUT LIMITATION THE IMPLIED WARRANTIES OF MERCHANTABILITY,
     TITLE AND FITNESS FOR A PARTICULAR USE.

15.5 Zhone represents and warrants to Solectron that it is the owner of all
     proprietary rights in the information provided to Solectron in order to
     manufacture the Products, and that it has the unqualified right to make
     available to Solectron, material and other information, including drawings,
     designs and specifications, and the order management and fulfillment
     system. Additionally, Zhone represents and warrants to Solectron that it is
     the owner of software provided to Solectron hereunder and/or has the right
     to supply the software. Zhone hereby grants to Solectron a license to use
     and reproduce the software, and any other documentation or information
     provided to Solectron for the purposes contemplated by this Agreement.

16.0 Breach; Remedies and Termination

16.1 The following failures in performance will be deemed a Material Breach by
     the applicable party:

     (i)  material failure by Solectron to meet committed delivery dates;
     (ii) material failure by Solectron to maintain the quality standards set
          forth in Section 12.1;
    (iii) failure by Zhone to pay for Products or Services as required under
          this Agreement.

16.2 If either party fails to meet any one or more of the terms and conditions
     as stated in this Agreement, or upon the occurrence of a Material Breach,
     Solectron and Zhone agree to negotiate in good faith to resolve such
     default or Material Breach. If the defaulting party fails to cure such
     default or Material Breach, or submit an acceptable written plan to resolve
     such default or Material Breach within thirty (30) days following notice of
     default or Material Breach, the nondefaulting party shall have the right to
     terminate this Agreement by furnishing the defaulting party with written
     notice of termination, which termination shall be effective within thirty
     (30) days of the date of such notice.

16.3 Either party may immediately terminate this Agreement if the other party
     (i) becomes insolvent; (ii) enters into or file a petition, arraignment or
     proceeding seeking an order for relief under the bankruptcy laws of its
     respective jurisdiction; (iii) enters into a receivership of any of its
     assets; or (iv) enters into a dissolution of liquidation of its assets or
     an assignment for the benefit of its creditors.

16.4 Upon termination of this Agreement or individual Statement of Work, Zhone
     agrees to reimburse Solectron for applicable charges as set forth in
     Sections 9.1 and 10.1. Except for termination due to Zhone's default or
     Material Breach, Solectron shall, at Zhone's election, complete all work in
     process and deliver such Product to Zhone's designated location. Upon any
     termination, Solectron shall work cooperatively with Zhone to ensure the
     orderly transfer of the Products to Zhone or its designated third party in
     a manner so as to minimize any adverse impact to Zhone.

17.0 Dispute Resolution

                                       14
<PAGE>

17.1 In the spirit of continued cooperation, the parties intend to and hereby
     establish the following dispute resolution procedure to be utilized in the
     unlikely event any controversy should arise out of or concerning the
     performance of this Agreement.

17.2 It is the intent of the parties that any dispute be resolved informally and
     promptly through good faith negotiation between Solectron and Zhone. Either
     party may initiate negotiation proceedings by written notice to the other
     party setting forth the particulars of the dispute. The parties agree to
     meet in good faith to jointly define the scope and a method to remedy the
     dispute. If these proceedings are not productive of a resolution, then
     either party may choose to escalate the problem to senior management.

17.3 Should any disputes remain existent between the parties after completion of
     the two-step resolution process set forth above, or in any event, more than
     thirty (30) days following written request by a party to escalate the
     dispute to senior management, then the parties shall promptly submit any
     dispute to mediation with an independent mediator as administered by the
     American Arbitration Association. In the event mediation is not successful
     in resolving the dispute, the parties agree to submit the dispute to
     binding arbitration in accordance with the then-current Commercial Rules
     and supervision of the American Arbitration Association. The arbitration
     will be held in the US headquarters city of the party not initiating the
     claim before a sole arbitrator who is knowledgeable in business information
     and electronic manufacturing services. The arbitrator will not have the
     power to award any damages excluded by, or in excess of, any damage
     limitations expressed in this Agreement. Issues of arbitrability will be
     determined in accordance solely with the federal substantive and procedural
     laws relating to arbitration; in all other respects, the arbitrator will be
     obligated to apply and follow the substantive law of the state specified in
     this Agreement. Each party will bear its own attorney's fees associated
     with the arbitration and other costs and expenses of the arbitration will
     be borne as provided by the rules of the American Arbitration Association.

18.0 Limitation of Liability

18.1 OTHER THAN DAMAGES ARISNG OUT OF SECTION 4.1 AND SECTION 10.1, IN NO EVENT,
     WHETHER AS A RESULT OF BREACH OF CONTRACT, WARRANTY, TORT (INCLUDING
     NEGLIGENCE), STRICT LIABILITY, PRODUCT LIABILITY, OR OTHERWISE, SHALL
     EITHER PARTY BE LIABLE TO THE OTHER FOR ANY SPECIAL, INCIDENTAL, INDIRECT,
     CONSEQUENTIAL, OR EXEMPLARY DAMAGES OF ANY KIND, INCLUDING WITHOUT
     LIMITATION, LOSS OF PROFITS, LOSS OF USE OR DATA OR INTERRUPTION OF
     BUSINESS, WHETHER OR NOT EITHER PARTY WAS ADVISED OF THE POSSIBILITY OF
     SUCH DAMAGE.

18.2 Solectron is performing work per specifications provided by Zhone.
     Therefore, Solectron shall not be liable for the technical adequacy or
     design of the product(s); nor shall Solectron be liable for the safety or
     regulatory compliance of the Product(s), including but not limited to
     ensuring that the Products meet applicable government or responsible agency
     regulations. Should the Products or changes fail to meet the applicable
     approvals, standards or regulations, Solectron may cease production until
     Zhone and Solectron agree to required changes and applicable qualifications
     are met, without being in breach of this Agreement. Zhone is responsible
     for obtaining required

                                       15
<PAGE>

     approvals relative to any changes and will be responsible for all costs
     attributable to such requirements. Zhone agrees to indemnify and save
     Solectron harmless from and against all losses, expenses or damages arising
     out of any claim resulting from Solectron's compliance with Zhone's
     specifications.

19.0 Intellectual Property Rights and Licenses

19.1 Scope. The provisions of this Section 19.0 will apply to the services
     -----
     provided by Solectron which are related to Manufacturing Services. If Zhone
     desires to engage Solectron to provide circuit, board, system and/or
     schematic design services, ASIC design services, or other specific services
     then the parties either will execute a separate agreement.

19.2 Agreements with Employees and Consultants. Each party shall have agreements
     -----------------------------------------
     with its employees and consultants such that ownership of such persons'
     inventions and authored works vests in the employer or in the entity which
     hired the consultant, respectively.

19.3 Pre-Existing Work Product. If either party creates or owns Pre- existing
     -------------------------
     Work Product: (a) such party ("owning party") shall solely own such
     Pre-existing Work Product (subject to any right of any third party),
     notwithstanding disclosure or delivery to the other party of such Pre-
     existing Work Product; (b) the owning party shall have the right to hold in
     its own name all Intellectual Property Rights that may be available in (or
     result from) such Pre-existing Work Product; and (c) the other party shall
     have no license, sublicense, right or immunity, either directly or
     indirectly, or by implication, estoppel or otherwise, under such
     Intellectual Property Rights, except as expressly provided elsewhere in
     this Agreement or in a separate written agreement.

19.4 Work Product Related to Product Design. To the extent that Work Product is
     --------------------------------------
     created, whether solely by either party or jointly by both parties, in the
     provision of Manufacturing Services under this Agreement, and such Work
     Product relates to Product Design, then: (a) Zhone shall solely own such
     Work Product, notwithstanding disclosure or delivery of such Work Product
     to Solectron; (b) Zhone shall have the right to hold in its own name all
     Intellectual Property Rights that may be available in (or result from) such
     Work Product; and (c) Solectron shall have no license, sublicense, right or
     immunity, either directly, indirectly, or by implication, estoppel or
     otherwise, under such Intellectual Property Rights, except as expressly
     provided elsewhere in this Agreement. Hereafter all such Work Product,
     together with all Pre-existing and Test Design Work Product solely owned by
     Zhone, shall be referred to as "Zhone Work Product".

19.5 Work Product Related to Manufacturing Design. To the extent that Work
     --------------------------------------------
     Product is created, whether solely by Solectron or jointly by Zhone and
     Solectron, in performing this Agreement, and such Work Product relates to
     Manufacturing Design, then: (a) Solectron shall solely own such Work
     Product, notwithstanding disclosure or delivery of such Work Product to
     Zhone; (b) Solectron shall have the right to hold in its own name all
     Intellectual Property Rights that may be available in (or result from) such
     Work Product; and (c) Zhone shall have no license, sublicense, right or
     immunity, either directly, indirectly, or by implication, estoppel or
     otherwise, under such Intellectual Property Rights, except as expressly
     provided elsewhere in this Agreement. Hereafter all such Work

                                       16
<PAGE>

     Product, together with all Pre-existing and Test Design Work Product solely
     owned by Solectron, shall be referred to as "Solectron Work Product."

19.6 Solectron Work Product License to Zhone. Notwithstanding anything to the
     ---------------------------------------
     contrary in this Agreement, to the extent that in connection with
     performing this Agreement, Solectron Work Product is disclosed or delivered
     to Zhone, or incorporated directly into the Products: Solectron grants to
     Zhone a worldwide, nonexclusive, fully paid-up, right and license under
     Solectron's Intellectual Property Rights (available in or resulting from
     the Solectron Work Product) to use such Solectron Work Product solely in
     connection with the Products; subject, however, to the condition that, to
     the extent that such Solectron Work Product is Confidential Information,
     the provisions of Section 14.0 shall apply.

19.7 Zhone Work Product License to Solectron. Notwithstanding anything to the
     ---------------------------------------
     contrary in this Agreement, to the extent that in connection with the
     performance of this Agreement, Zhone Work Product is disclosed or delivered
     to Solectron, or is incorporated directly into the Products: Zhone grants
     to Solectron during the term of this Agreement, a worldwide, nonexclusive,
     nontransferable, fully paid-up, right and license under Zhone's
     Intellectual Property Rights (available in or resulting from the Zhone Work
     Product) to do any of the following solely for the purpose of manufacturing
     Product and providing related services under this Agreement: to use, make,
     have made, reproduce, and prepare derivative works based upon such Zhone
     Work Product; subject, however, to the condition that to the extent that
     such Zhone Work Product is Confidential Information, the provisions of
     Section 14.0 shall apply.

19.8 Work Product Related to Test Design. To the extent that Work Product is
     -----------------------------------
     created, whether solely by Solectron or jointly by Zhone and Solectron, in
     performing this Agreement, and such Work Product relates to Test Design,
     then: (a) the party (or parties) creating such Work Product shall solely
     (or jointly, as the case may be) own such Work Product, notwithstanding
     disclosure or delivery of such Work Product to the non-creating party; (b)
     the party (or parties) creating such Work Product shall have the right to
     hold in its own name (or their joint names, as the case may be) all
     Intellectual Property Rights that may be available in (or result from) such
     Work Product; and (c) the other party, if applicable, shall have no
     license, sublicense, right or immunity, either directly, indirectly, or by
     implication, estoppel or otherwise, under such Intellectual Property
     Rights, except as expressly provided elsewhere in this Agreement.  If the
     parties jointly own such Work Product, they shall have no obligation to
     account to each other for any use of such Work Product.

19.9 No Other Licenses Granted.  Except as expressly provided otherwise in this
     -------------------------
     Agreement, nothing in this Agreement shall be deemed to grant to either
     party, either directly or indirectly, or by implication, estoppel or
     otherwise, any license, sublicense, right or immunity under any
     Intellectual Property Rights of the other party or its licensors.

20.0 Intellectual Property Indemnification

20.1 Zhone will defend, at its expense, any action or claim brought against
     Solectron or its subsidiaries alleging that Products provided by Solectron
     under this Agreement infringe any patent, copyright, trademark, or any
     other proprietary right, and Zhone will pay all costs and damages
     (including

                                       17
<PAGE>

     attorney's fees) incurred by Solectron or its subsidiaries that are
     attributable to such actions or claims; provided that Zhone is promptly
     notified in writing and furnished a copy of each allegation of infringement
     and is given authority, information, and assistance (at Zhone's expense)
     necessary to defend or settle such claim. Zhone shall have no liability
     under this Section for a claim or suit if the alleged infringement or
     violation is the result of Solectron's unauthorized modification or
     alteration of the Specification, or Zhone' compliance with Solectron's
     specifications, designs, or manufacturing processes.

20.2 Solectron will defend, at its expense, any action or claim brought against
     Zhone alleging that Solectron's manufacturing processes utilized in the
     performance of this Agreement infringe any patent, copyright, trademark, or
     any other proprietary right, and Solectron will pay all costs and damages
     (including attorney's fees) incurred by Zhone that are attributable to such
     actions or claims; provided that Solectron is promptly notified in writing
     and furnished a copy of each allegation of infringement and is given
     authority, information, and assistance (at Solectron's expense) necessary
     to defend or settle such claim.  Solectron shall have no liability under
     this Section for any claim or suit where:  (i) infringement or violation is
     attributable to Solectron's incorporation of Zhone's Specification into the
     Product unless Solectron knew that such designs, if so incorporated, would
     so infringe or violate; and (ii) such claim or suit would have been avoided
     but for the combination, operation, or use of the Product with devices,
     parts, or software not supplied by Solectron unless Solectron knew that
     such combination, operation or use would so infringe or violate.

21.0 Personal Injury Indemnification

21.1 Each party agrees to indemnify and hold the other harmless against any
     loss, cost or expense, including reasonable attorneys' fees, finally
     awarded against the other in connection with a claim by a third party for
     personal injury or property damage, to the extent that such damage is
     caused by a negligent act or omission by the indemnifying party or its
     agents. Each indemnitor's obligations hereunder shall be conditioned upon
     receiving a prompt notice of each such claim from the indemnitee and the
     sole authority to defend, and the indemnitee shall cooperate and provide
     reasonable assistance to the indemnitor in defense of the claim. Each party
     agrees to carry commercial liability, property damage, and automobile
     liability coverage, including contractual endorsement and products hazard
     coverage in reasonable amounts.

22.0 Independent Contractor; Competition

22.1 Each of the parties hereto shall conduct the work to be performed hereunder
     as an independent contractor and not as an agent or employee of the other
     party. Subject to the terms and conditions of this Agreement, each party
     shall choose the means to be employed and the manner of carrying out its
     obligations hereunder.

22.2  Nothing in this Agreement shall limit the right of Zhone or Solectron to
     develop, have developed, procure and/or market products or services now or
     in the future, including any which may be competitive with those which are
     the subject of this Agreement.  Neither party shall be required to disclose
     planning information to the other.

                                       18
<PAGE>

23.0 General

23.1 Each party to this Agreement will maintain insurance to protect itself from
     claims (i) by the party's employees, agents and subcontractors, (ii) for
     damages because of injury to or destruction of tangible property resulting
     out of any negligent act, omission or willful misconduct of the party or
     the party's employees or subcontractors, (iii) for damages because of
     bodily injury, sickness, disease or death of its employees or any other
     person arising out of any negligent act, omission, or willful misconduct of
     the party or the party's employees, agents or subcontractors.

23.2 Neither party shall delegate, assign or transfer its rights or obligations
     under this Agreement, whether in whole or part, without the written consent
     of the other party; provided, however, that either party may assign this
     Agreement to a wholly owned subsidiary upon written notice to the other
     party subject to the condition that such assignment will be null and void
     in the event that such subsidiary ceases to be wholly owned by the
     contracting party. Failure by either party to enforce any provision of this
     Agreement shall not be deemed to be a continuing waiver or a waiver of any
     other default or other term and condition.

23.3 Neither party shall be liable for any failure or delay in its performance
     under this Agreement due to acts of God, acts of civil or military
     authority, fires, floods, earthquakes, riots, wars or any other cause
     beyond the reasonable control of the delayed party provided that the
     delayed party: (i) gives the other party written notice of such cause
     within fifteen (15) days of the discovery of the event; and (ii) uses its
     reasonable efforts to remedy such delay in its performance. If such delay
     shall continue for more than thirty (30) days, the party injured by the
     inability of the other to perform shall have the right upon written notice
     to the other party to either (a) terminate this Agreement as set forth in
     Section 16.0, or (b) treat this Agreement as suspended during the delay,
     find alternative sourcing, and reduce any commitment in proportion to the
     duration of the delay.

23.4 Each party agrees that it will not knowingly (a) export or re-export,
     directly or indirectly, any technical data (as defined by the U.S. Export
     Administration Regulations), including software received from the other
     under this Agreement, (b) disclose such technical data for use in, or (c)
     export or re-export, directly or indirectly, any direct product of such
     technical data, including software, to any destination to which such export
     or re-export is restricted or prohibited by U.S. or non-U.S. law without
     obtaining prior authorization from U.S. Department of Commerce and other
     competent government authorities to the extent required by those laws. This
     clause shall survive termination or cancellation of this Agreement.

23.5 All notices required by this Agreement shall be in writing and delivered
     postage paid to the addresses set forth below or at such other address as
     either party may furnish to the other in writing:

          To Solectron:    Solectron Corporation
                           847 Gibraltar Drive
                           Milpitas, CA  95035
                           Attn:  Saeed Zohouri, Sr. V.P. & COO

                                       19
<PAGE>

          with a copy to    Solectron Texas, L.P.
                            12455 Research Blvd.
                            Austin, TX 78759
                            Attn: Joe Farmer, Director, M/S 2197
                            Attn: Legal Department

          To Zhone:         Zhone Technologies, Inc.
                            7677 Oakport Street, Suite 1040,
                            Oakland, CA 94621
                            Attn: Ebrahim Abassi, V.P. Operations

          with a copy to    Zhone Technologies, Inc.
                            7677 Oakport Street, Suite 1040
                            Oakland, CA 94621
                            Attn: General Counsel

23.6  Failure of either party to enforce any term or condition of this Agreement
      will not be deemed to be a waiver of such term or condition. If any
      provision of this Agreement is held to be invalid, the other provisions
      will not be affected.

23.7  This Agreement, the Exhibits and the Statement(s) of Work constitute the
      entire agreement of the parties concerning the subject matter covered
      herein, and shall supersede all prior discussions, oral or other
      agreements. This Agreement may be executed in one or more counterparts,
      each of which will be deemed the original, but all of which will
      constitute but one and the same document. The parties agree this
      Agreement, including the Exhibits, may not be modified except in writing
      signed by both parties.

23.8  The parties hereto agree that the terms and conditions contained in either
      party's printed or electronic documents shall not apply to the purchase
      and/or sale of the Products and that the terms and conditions set forth
      herein shall govern all such transactions; provided, however, that the
      terms and conditions typed or hand-written on the face of a purchase
      order, acknowledgment or other document relating to the Product types,
      quantities, prices, ship-to locations and shipment dates shall, if
      accepted by both parties hereto, also apply to all such transactions and
      shall augment the terms and conditions set forth herein.

23.9  The parties hereto agree that this Agreement shall not be construed,
      enforced or governed by the United Nations Convention on Contracts for the
      International Sale of Goods; rather this Agreement is entered into in the
      State of California, U.S.A. and shall be construed, enforced and governed
      solely in accordance with the laws of the State of California, U.S.A
      without giving effect to any choice of law provisions thereof. In any
      action to enforce this Agreement, the prevailing party shall be awarded
      all court or arbitration costs and reasonable attorney fees incurred.

23.10 Each party shall comply with all applicable laws (including environmental
      laws), ordinances, regulations and codes, foreign or domestic, and shall
      maintain all required permits, certificates, licenses, approvals and
      inspections in performance of this Agreement.

                                       20
<PAGE>

23.11 Neither party shall engage in publicity related to this Agreement without
      the prior written approval of the other party.

23.12 The provisions of Sections 1, 2, 4, 8, 9, 10, 14, 15, 17, 18, 19, 20, 21,
      and 23 shall survive expiration or termination of this Agreement.

Agreed:

SOLECTRON CORPORATION                         ZHONE TECHNOLOGIES, INC.

By:    /s/  Susan Wang                        By:
      ---------------------------                ------------------------------

Name: Susan Wang                              Name:
      ---------------------------                ------------------------------

Title: SR. VP, CFO & SECRETARY                Title:
      ---------------------------                  ----------------------------

Date:                                         Date:
      ---------------------------                ------------------------------

                                       21
<PAGE>

23.13 Neither party shall engage in publicity related to this Agreement without
      the prior written approval of the other party.

23.14 The provisions of Sections 1, 2, 4, 8, 9, 10, 14, 15, 17, 18, 19, 20, 21,
      and 23 shall survive expiration or termination of this Agreement.

Agreed:

SOLECTRON CORPORATION                     ZHONE TECHNOLOGIES, INC.

By:                                       By: /s/  Ebrahim Abbasi
   ---------------------------                ------------------------------

Name:                                     Name: Ebrahim Abbasi
     -------------------------                 -----------------------------

Title:                                    Title: VP, Operations
      ------------------------                  ----------------------------

Date:                                     Date: March 10, 2000
      ------------------------                  ----------------------------

                                       22
<PAGE>

                                  EXHIBIT A-1

                                    Products

IMACS Product Family

                                       23
<PAGE>

                                  EXHIBIT A-2

                                    Products

Sechtor and ARCA-DACS Products

                                       24
<PAGE>

                                  EXHIBIT B-1

                                 Pricing Model

                                    for the

                              IMACS Product Family

                                       25
<PAGE>

                        Zhone Order Fulfillment Pricing

<TABLE>
<CAPTION>
Costing/Pricing for Processing Product to FGI Status (unit charge)
         P/N          Description           Mat'l          Cost of         Total            PWBA Assy              PWBA Test
                                                         Acquisition       Mat'l      Time         Rate        Time         Rate
<S>                 <C>                     <C>          <C>              <C>         <C>         <C>          <C>         <C>
                                                             8.0%                                 $40.70                   $40.70

2525-N4N

2525-N9N

Costing/Pricing for Processing Product from FGI through Systems Configuration (monthly charge)
P/N                    Number of                   Systems                         QA                            Total Systems
                    Systems Shipped          Configuration & Test                                             Configuration Cost
                                             Time            Rate           Time        Rate
                                              Hr            $40.70         0.1333      $40.70

Costing/Pricing for Order Fulfillment Services (monthly charge)
                      Number of             Time            Rate          Margin     Goodwill     Monthly
                    Items Shipped          0.1666          $40.70          6.0%       Margin       Charge
                                                                         (/0.94)       5.0%
</TABLE>

<TABLE>
<CAPTION>
Costing/Pricing for Processing Product to FGI Status (unit charge)
        25% Pre-                 Common            Re-Test       Total PWBA           FGI     Margin   Goodwill
        Test Mfg               Value Add             5.0%     Assy, Test & CVA       Cost      6.0%     Margin      Qty     Extended
    Time         Rate      Time           Rate                Time         Rate               (/0.94)    5.0%       Per      Value
<S>             <C>       <C>           <C>       <C>         <C>        <C>        <C>      <C>       <C>          <C>     <C>
                $40.70                   $40.70                           $40.70

                                                                                                          Value per system

                                                                                                          Value per system

Costing/Pricing for Processing Product from FGI through Systems Configuration (monthly charge)
   Margin      Goodwill       Monthly
    6.0%        Margin        Charge
   (/0.94)       5.0%
</TABLE>
<PAGE>

                                  EXHIBIT B-1

                                    Pricing

                                    For the

                         Sechtor and ARCA-DACS Products

Pricing will be provided via quotation.

                                       27
<PAGE>

                                  EXHIBIT C-1
               Flexibility/Cancellation/Component Liability Terms

                              IMACS Product Family

                            Intentionally Left Blank

                                       28
<PAGE>

                                  EXHIBIT C-2

               Flexibility/Cancellation/Component Liability Terms

                         Sechtor and ARCA-DACS Products

                            Intentionally Left Blank

                                       29
<PAGE>

                                   EXHIBIT D

                            Out of Warranty Service

                                       30
<PAGE>

                                   EXHIBIT E

                  PASSIVE COMMODITY SUBSTITUTION APPROVAL FORM
                  --------------------------------------------

                            ZHONE TECHNOLOGIES, INC

This form sets forth the conditions under which Solectron Corporation
("Solectron") may substitute certain components for those specified on Zhone's
BOM and sourced through Zhone's approved vendor list (AVL).  Zhone's signature
will constitute its express authorization for any substitutions made by
Solectron in accordance with the criteria and conditions listed below.

     Resistors:  Substitution is approved for these components using the
     following criteria:

     .    Equal/Better than Tolerance (i.e., 5% when AVL specs 10%)

     .    Equal/Better than Zhone Rating (i.e., 1/4 watt when AVL specs 1/8
          watt)

     Conditions:

          1.   Applies to carbon film, metal film, and surface mount resistors
               only.

          2.   Wire wound resistors must meet AVL, no exceptions.

          3.   In all cases, resistance values must meet AVL specifications.

          4.   The temperature coefficient (PPM/DEG C) will be "equal to" or
               "better than".

          5.   Substitution can be done provided form, fit, and function meet
               original specification.

     Inductors:  Substitution is approved for these components using the
     following criteria:

     .    Equal/Better than Tolerance (i.e., 10% when AVL specs 20%)

     Conditions:

          1.   Surface mount shall be of the same size and pitch as specified.

          2.   The temperature coefficient (PPM/DEG C) will be "equal to" or
               "better than".

          3.   Q Value must be "equal to" unless AVL reads Q=XX or greater.

          4.   Substitution can be done provided form, fit, and function meet
               original specification.

                                       31
<PAGE>

     All substitutions are limited to Solectron,  Preferred+,  and Preferred
     suppliers, and Zhone approved suppliers.

     Capacitors:   Substitution is approved for these components using the
     following criteria:

     .    Equal/Better than Tolerance (i.e., 10% when AVL specs 20%)

     .    Equal/Better than Voltage (i.e., 20 volt when AVL specs 1 volt)

     .    Equal/Better than Dielectric (i.e., NPO in place of X7R or X5U and X7R
          in place of Z5U.)

     Conditions:

               1.   Tantalum or electrolytic capacitors shall be replaced by the
                    same type.

               2.   Surface mount shall be of the same size and pitch as
                    specified.

               3.   Reel and Ammo pack radial/axial lead components with a
                    smaller case size is acceptable.

               4.   The temperature coefficient (PPM/DEG C) will be "equal to"
                    or "better than".

               5.   The type of film will remain the same (i.e., polyester can
                    not be substituted for polycarbonate, and polycarbonate can
                    not be substituted for polysulfone, etc.)

               6.   The type of construction will remain the same (i.e., WRAP
                    and fill cannot be substituted for hermetically sealed,
                    etc.)

               7.   Substitution can be done provided form, fit, and function
                    meet original specification.

ZHONE APPROVES THESE SUBSTITUTIONS WITH THE AUTHORIZED SIGNATURE BELOW:

ZHONE TECHNOLOGIES, INC.

Signature: ___________________________
Name:  _______________________________
Title: _______________________________
Date: ________________________________

                                       32
<PAGE>

                 CONNECTOR COMMODITY SUBSTITUTION APPROVAL FORM
                 ----------------------------------------------

                            ZHONE TECHNOLOGIES, INC.

This form sets forth the conditions under which Solectron may substitute certain
components for those specified on Zhone's Bills of Materials (BOM) and sourced
through Zhone's approved vendor list (AVL).  Zhone's signature will constitute
its' express authorization for any substitutions made by Solectron in accordance
with the criteria and conditions listed below.

     Connector:  Substitution is approved for these components using the
     following criteria:

     .    Thicker gold plating (i.e., 30u > 15u > gold flash)

     .    Higher temperature material (i.e., LCP > polyester)

     .    Retention, i.e., kinked, leads

     .    Different color material

     In addition, the following substitutions may also be made for the
     designated part type:

     .    Headers - substitute "breakaway" for "solid"

     .    DSUB's - substitute "screwlock installed" for units with separate
          screwlocks

     .    PLCC Sockets - substitute low insertion force for standard insertion
          force

     .    DIP Sockets - substitute better than plating (i.e., beryllium>
          phosphor bronze > copper alloy and, dual leaf > single leaf)

     .    SIMMs - substitute metal latches for plastic latches

     .    DIN - substitute level I > level II > level IIII

     Exceptions:

     .    SIMMs - substation of gold vs. tin plating on contacts is not allowed

                                       33
<PAGE>

     All substitutions are limited to Solectron, Preferred+ and Preferred
     suppliers and, Zhone approved suppliers.

ZHONE APPROVES THESE SUBSTITUTIONS WITH THE AUTHORIZED SIGNATURE BELOW:

ZHONE TECHNOLOGIES, INC.

Signature: ___________________________

Name:  _______________________________

Title: _______________________________

Date: ________________________________

                                       34<PAGE>

                            ZHONE ACQUISITION CORP.

           (to be merged with and into Premisys Communications, Inc.

              and then to be succeeded by Premisys Systems, LLC)

                           _________________________

                                 $125,000,000

                               CREDIT AGREEMENT

                         dated as of November 29, 1999

                           _________________________

CREDIT    FIRST
SUISSE    BOSTON
<PAGE>

                               TABLE OF CONTENTS
                               -----------------

<TABLE>
<CAPTION>
                                                                                                                           Page
                                                                                                                           -----
<S>                                                                                                                        <C>
SECTION 1. DEFINITIONS.....................................................................................................   1

     1.1 Defined Terms.....................................................................................................   1
         -------------

            "Commitment....................................................................................................   4
             ----------

            "Uniform Customs...............................................................................................  15
             ---------------

     1.2 Other Definitional Provisions.....................................................................................  15
         -----------------------------

SECTION 2. AMOUNT AND TERMS OF TERM LOAN COMMITMENTS.......................................................................  15

     2.1 Term Loans........................................................................................................  15
         ----------

     2.2 Procedure for Term Loan Borrowing.................................................................................  15
         ---------------------------------

     2.3 Amortization of Term Loans........................................................................................  16
         --------------------------

     2.4 Use of Proceeds of Term Loans.....................................................................................  17
         -----------------------------

SECTION 3. AMOUNT AND TERMS OF ACQUISITION LOAN COMMITMENTS................................................................  17

     3.1 Acquisition Term Loans............................................................................................  17
         ----------------------

     3.2 Procedure for Acquisition Loan Borrowing..........................................................................  17
         ----------------------------------------

     3.3 Maturity of Acquisition Loans.....................................................................................  18
         -----------------------------

     3.4 Use of Proceeds of Acquisition Loans..............................................................................  18
         ------------------------------------

SECTION 4. PROVISIONS RELATING TO THE LOANS; FEES AND PAYMENTS.............................................................  18

     4.1 Repayment of Loans; Evidence of Debt..............................................................................  18
         ------------------------------------

     4.2 Commitment Fee....................................................................................................  19
         --------------

     4.3 Optional Prepayments..............................................................................................  19
         --------------------

     4.4 Optional Termination or Reduction of Aggregate Acquisition Loan Commitment........................................  20
         --------------------------------------------------------------------------

     4.5 Mandatory Prepayments.............................................................................................  20
         ---------------------

     4.6 Conversion and Continuation Options...............................................................................  20
         -----------------------------------

     4.7 Minimum Amounts and Maximum Number of Tranches....................................................................  21
         ----------------------------------------------
</TABLE>
<PAGE>

<TABLE>
<S>                                                                                                                          <C>
     4.8 Interest Rates and Payment Dates..................................................................................  21
         --------------------------------

     4.9 Computation of Interest and Fees..................................................................................  21
         --------------------------------

     4.10 Inability to Determine Interest Rate.............................................................................  22
          ------------------------------------

     4.11 Pro Rata Treatment and Payments..................................................................................  22
          -------------------------------

     4.12 Illegality.......................................................................................................  23
          ----------

     4.13 Requirements of Law..............................................................................................  24
          -------------------

     4.14 Taxes............................................................................................................  25
          -----

     4.15 Indemnity........................................................................................................  26
          ---------

     4.16 Certain Fees.....................................................................................................  26
          ------------

     4.17 Change of Lending Office.........................................................................................  26
          ------------------------

SECTION 5. REPRESENTATIONS AND WARRANTIES..................................................................................  27

     5.1 Financial Condition...............................................................................................  27
         -------------------

     5.2 No Change.........................................................................................................  28
         ---------

     5.3 Corporate Existence; Compliance with Law..........................................................................  28
         ----------------------------------------

     5.4 Corporate Power; Authorization; Enforceable Obligations...........................................................  28
         -------------------------------------------------------

     5.5 No Legal Bar......................................................................................................  29
         ------------

     5.6 No Material Litigation............................................................................................  29
         ----------------------

     5.7 No Default........................................................................................................  29
         ----------

     5.8 Ownership of Property; Liens......................................................................................  29
         ----------------------------

     5.9 Intellectual Property.............................................................................................  30
         ---------------------

     5.10 No Burdensome Restrictions.......................................................................................  30
          --------------------------

     5.11 Taxes............................................................................................................  30
          -----

     5.12 Federal Regulations..............................................................................................  30
          -------------------

     5.13 ERISA............................................................................................................  30
          -----

     5.14 Investment and Holding Company Status............................................................................  31
          -------------------------------------
</TABLE>
<PAGE>

<TABLE>
<S>                                                                                                                             <C>
     5.15 Environmental Matters.............................................................................................      31
          ---------------------

     5.16 Security Documents................................................................................................      32
          ------------------

     5.17 Acquisition Documents.............................................................................................      32
          ---------------------

     5.18 Capital Call Obligations..........................................................................................      32
          ------------------------

     5.19 Accuracy and Completeness of Information..........................................................................      33
          ----------------------------------------

     5.20 Solvency..........................................................................................................      33
          --------

SECTION 6. CONDITIONS PRECEDENT.............................................................................................      33

     6.1 Conditions to Initial Loans........................................................................................      33
         ---------------------------

     6.2 Conditions to Term Loan............................................................................................      36
         -----------------------

     6.3 Conditions to Each Loan............................................................................................      37
         -----------------------

SECTION 7. AFFIRMATIVE COVENANTS............................................................................................      37

     7.1 Financial Statements...............................................................................................      37
         --------------------

     7.2 Certificates; Other Information....................................................................................      38
         -------------------------------

     7.3 Payment of Obligations.............................................................................................      39
         ----------------------

     7.4 Conduct of Business and Maintenance of Existence...................................................................      39
         ------------------------------------------------

     7.5 Maintenance of Property; Insurance.................................................................................      39
         ----------------------------------

     7.6 Inspection of Property; Books and Records; Discussions.............................................................      40
         ------------------------------------------------------

     7.7 Notices............................................................................................................      40
         -------

     7.8 Environmental Laws.................................................................................................      41
         ------------------

     7.9 Further Assurances.................................................................................................      41
         ------------------

     7.10 Additional Collateral.............................................................................................      41
          ---------------------

     7.11 Consummation of Merger............................................................................................      42
          ----------------------

SECTION 8. NEGATIVE COVENANTS...............................................................................................      42

     8.1 Financial Condition Covenants......................................................................................      42
         -----------------------------

     8.2 Limitation on Indebtedness.........................................................................................      43
         --------------------------
</TABLE>
<PAGE>

<TABLE>
<S>                                                                                                                             <C>
     8.3 Limitation on Liens................................................................................................     44
         -------------------

     8.4 Limitation on Guarantee Obligations................................................................................     45
         -----------------------------------

     8.5 Limitation on Fundamental Changes..................................................................................     45
         ---------------------------------

     8.6 Limitation on Sale of Assets.......................................................................................     45
         ----------------------------

     8.7 Limitation on Leases...............................................................................................     46
         --------------------

     8.8 Limitation on Restricted Payments..................................................................................     46
         ----------------------------------

     8.9 Limitation on Capital Expenditures.................................................................................     47
         ----------------------------------

     8.10 Limitation on Investments, Loans and Advances.....................................................................     47
          ---------------------------------------------

     8.11 Limitation on Transactions with Affiliates........................................................................     48
          ------------------------------------------

     8.12 Limitation on Sales and Leasebacks................................................................................     48
          ----------------------------------

     8.13 Limitation on Changes in Fiscal Year..............................................................................     48
          ------------------------------------

     8.14 Limitation on Negative Pledge Clauses.............................................................................     48
          -------------------------------------

     8.15 Limitation on Lines of Business...................................................................................     48
          -------------------------------

     8.16 Rights under Acquisition Documents................................................................................     49
          ----------------------------------

     8.17 Asset Transfer....................................................................................................     49
          --------------

     8.18 Optional Payments and Modifications of Certain Debt Instruments...................................................     50
          ---------------------------------------------------------------

SECTION 9. EVENTS OF DEFAULT................................................................................................     50

SECTION 10. THE ADMINISTRATIVE AGENT........................................................................................     54

     10.1 Appointment.......................................................................................................     54
          -----------

     10.2 Delegation of Duties..............................................................................................     54
          --------------------

     10.3 Exculpatory Provisions............................................................................................     54
          ----------------------

     10.4 Reliance by Administrative Agent..................................................................................     54
          --------------------------------

     10.5 Notice of Default.................................................................................................     55
          -----------------

     10.6 Non-Reliance on Administrative Agent and Other Lenders............................................................     55
          ------------------------------------------------------

     10.7 Indemnification...................................................................................................     56
          ---------------
</TABLE>
<PAGE>

     10.8  Administrative Agent in Its Individual Capacity................... 56

     10.9  Successor Administrative Agent.................................... 56

SECTION 11. MISCELLANEOUS.................................................... 56

     11.1  Amendments and Waivers............................................ 56

     11.2  Releases of Collateral and Credit Support......................... 57

     11.3  Notices........................................................... 59

     11.4  No Waiver; Cumulative Remedies.................................... 59

     11.5  Survival of Representations and Warranties........................ 60

     11.6  Payment of Expenses and Taxes..................................... 60

     11.7  Successors and Assigns; Participations and Assignments............ 60

     11.8  Adjustments; Set-off.............................................. 63

     11.9  Counterparts...................................................... 64

     11.10 Severability...................................................... 64

     11.11 Integration....................................................... 64

     11.12 GOVERNING LAW..................................................... 64

     11.13 Submission To Jurisdiction; Waivers............................... 64

     11.14 Acknowledgments................................................... 65

     11.15 WAIVERS OF JURY TRIAL............................................. 65

     11.16 Confidentiality. Each of the Administrative Agent and the Lenders, on
           behalf of itself and each of its affiliates, agents, directors,
           officers and employees, agrees to keep confidential all non-public
           information provided to it by any Credit Party pursuant to this
           Agreement that is clearly designated by such Credit Party in writing
           as "confidential"; provided that nothing herein shall prevent the
           Administrative Agent or any Lender from disclosing any such
           information (a) to the Administrative Agent, any other Lender or any
           affiliate, agent, director, officer or employee of any Lender, (b) to
           any Transferee or prospective Transferee which agrees to comply with
           the provisions of this Section, (c) any of its employees, directors,
           agents, attorneys, accountants and other professional advisors, (d)
           upon the request or demand of any Governmental Authority having
           jurisdiction over it, (e) in response to any order of any court or
           other
<PAGE>

           Governmental Authority or as may otherwise be required pursuant
           to any Requirement of Law, (f) if requested or required to do so in
           connection with any litigation or similar proceeding, (g) which has
           been publicly disclosed other than in breach of this Section 11.16,
           (h) to the National Association of Insurance Commissioners or any
           similar organization or any nationally recognized rating agency that
           requires access to information about a Lender's investment portfolio
           in connection with ratings issued with respect to such Lender or (i)
           in connection with the exercise of any right or remedy hereunder or
           under any other Credit Document................................... 65
<PAGE>

                                                                            Page
                                                                            ----

     SCHEDULES
------------------------------------------------------------------------------
Schedule I                             Lenders; Commitments

Schedule II                            Addresses for Notices

Schedule 5.9                           Intellectual Property

Schedule 8.2                           Existing Indebtedness

Schedule 8.3                           Existing Liens

Schedule 8.4                           Existing Guarantee Obligations

Schedule 8.17                          Subsidiaries

     EXHIBITS
------------------------------------------------------------------------------
Exhibit A                    Form of Term Loan Note

Exhibit B                    Form of Acquisition Note

Exhibit C-1                  Form of Capital Call Agreement

Exhibit C-2                  Form of Assignment of Capital Call Rights

Exhibit D-1                  Form of Initial Collateral Agreement

Exhibit D-2                  Form of AcquisitionCo Cash Collateral Agreement

Exhibit E                    Form of Premisys Escrow Agreement

Exhibit F                    Form of Subsequent Collateral Agreement

Exhibit G                    Form of LegacyCo Cash Collateral Agreement

Exhibit H                    Form of Assumption Agreement

Exhibit I                    Form of License Letter

Exhibit J                    Form of Assignment and Acceptance

Exhibit K-1                  Form of Notice of Borrowing (Drawings)

Exhibit K-2                  Form of Notice of Borrowing (Continuations)

                                    -viii-
<PAGE>

                                                                            Page
                                                                            ----

Exhibit K-3    Form of Notice of Borrowing (Conversions)

Exhibit L      Form of Zhone Subordinated Note

                                     -ix-
<PAGE>

                                                                               1

               CREDIT AGREEMENT, dated as of November 29, 1999, among:

(a)  ZHONE ACQUISITION CORP., a Texas corporation ("AcquisitionCo") (to be
                                                    -------------
     merged with and into Premisys Communications, Inc. and then to be succeeded
     by Premisys Systems, LLC);

(b)  the Lenders (as hereinafter defined) from time to time parties hereto; and

(c)  CREDIT SUISSE FIRST BOSTON, as administrative agent (in such capacity, the
     "Administrative Agent") for the Lenders.
      --------------------

                             W I T N E S S E T H:
                             - - - - - - - - - -

         WHEREAS, AcquisitionCo has entered into the Agreement and Plan of
Merger, dated as of October 20, 1999 (as amended, supplemented or otherwise
modified from time to time in accordance with the terms hereof, the "Merger
                                                                     ------
Agreement") among AcquisitionCo, Zhone Technologies, Inc., a Delaware
---------
corporation ("Zhone"), and Premisys Communications, Inc., a Delaware corporation
              -----
("Premisys"), pursuant to which AcquisitionCo has commenced a tender offer for
  --------
all of the issued and outstanding capital stock (all of such capital stock and
any related options collectively, the "Shares") of Premisys (the "Tender
                                       ------                     ------
Offer");
-----

          WHEREAS, as promptly as is practicable following the consummation of
the Tender Offer, the acquisition of the Shares tendered pursuant thereto (the
"Tendered Shares") and the completion (if necessary) of a proxy solicitation,
 ---------------
AcquisitionCo will be merged with and into Premisys, with Premisys being the
survivor of such merger (the "Merger");
                              ------

          WHEREAS, following the consummation of the Merger, Premisys (as the
survivor of the Merger) will transfer certain existing product lines of Premisys
and its obligations on account of the Term Loans (as hereinafter defined) to
Premisys Systems, LLC, a Delaware limited liability company ("LegacyCo"; such
                                                              --------
transfers, the "Asset Transfer");
                --------------

          WHEREAS, AcquisitionCo has requested that the Lenders make loans to it
for the purpose of financing the Tender Offer, the Merger and the Asset Transfer
(collectively, the "Transaction") and for the other purposes permitted by this
                    -----------
Agreement;

          WHEREAS, the Lenders are willing to make such loans, and the
Administrative Agent is willing to assume its obligations hereunder, only upon
the terms and subject to the conditions set forth herein;

          NOW, THEREFORE, in consideration of the premises and mutual covenants
contained herein, the parties hereto hereby agree as follows: have the following
meanings:

                            SECTION 1. DEFINITIONS

     1.1  Defined Terms. As used in this Agreement, the following terms shall
          -------------
have the following meanings:

          "ABR": for any day, a rate per annum equal to the greater of (a) the
           ---
Prime Rate in effect on such day and (b) the Federal Funds Effective Rate in
effect on such day plus 1/2 of 1%.
<PAGE>

                                                                               2

Any change in the ABR due to a change in the Prime Rate or the Federal Funds
Effective Rate shall be effective as of the opening of business on the effective
day of such change in the Prime Rate or the Federal Funds Effective Rate,
respectively.

          "ABR Loans": Loans the rate of interest applicable to which is based
           ----------
upon the ABR.

          "Acquisition":  as defined in the recitals hereto.
           -----------

          "AcquisitionCo":  as defined in the preamble hereto.
           -------------

          "AcquisitionCo Cash Collateral Agreement": the Cash Collateral
           ----------------------------------------
Agreement, substantially in the form of Exhibit D-2, made by AcquisitionCo in
favor of the Administrative Agent, as the same may be amended, supplemented or
otherwise modified from time to time.

          "Acquisition Documents":  the collective reference to the Tender Offer
           ---------------------
Documents, the Merger Agreement and all other documents and information sent by
AcquisitionCo or any of its Subsidiaries or Premisys to the shareholders of
Premisys or filed with the SEC in connection with the Transaction.

          "Acquisition Loan Commitment":  as to any Acquisition Lender, its
           --------------------------------
obligation to make its Acquisition Loans to the Borrower hereunder in an
aggregate principal amount not to exceed the amount set forth opposite such
Acquisition Lender's name on Schedule I under the heading "Acquisition Loan
Commitment".

          "Acquisition Loan Commitment Percentage": as to any Acquisition Lender
           --------------------------------------
at any time, the percentage which such Acquisition Lender's Acquisition Loan
Commitment then constitutes of the Aggregate Acquisition Loan Commitment (or, at
any time after the Closing Date, the percentage which the aggregate principal
amount of such Term Loan Lender's Acquisition Loans then outstanding constitutes
of the aggregate principal amount of the Acquisition Loans then outstanding).

          "Acquisition Lender": each bank or other financial institution holding
           ------------------
an Acquisition Loan Commitment hereunder (or, after the Closing Date and subject
to the provisions of subsection 11.7(d), holding any Acquisition Loans
hereunder); collectively, the "Acquisition Lenders".
                               --------------------

          "Acquisition Loan":  as defined in subsection 3.1.
           ----------------

          "Acquisition Note":  as defined in subsection 4.1(e).
           ----------------

          "Administrative Agent":  as defined in the preamble hereto.
           --------------------

          "Affiliate": as to any Person, any other Person (other than a
           ---------
 Subsidiary) which, directly or indirectly, is in control of, is controlled by,
 or is under common control with, such Person. For purposes of this definition,
 "control" of a Person means the power, directly or indirectly, either to (a)
 vote 10% or more of the securities having ordinary voting power for the
<PAGE>

                                                                               3

election of directors of such Person or (b) direct or cause the direction of the
management and policies of such Person, whether by contract or otherwise.

          "Aggregate Acquisition Loan Commitment": $75,000,000, as such amount
           -------------------------------------
may be reduced from time to time pursuant to this Agreement.

          "Aggregate Term Loan Commitment": $50,000,000, as such amount may be
           ------------------------------
reduced from time to time pursuant to this Agreement.

          "Agreement":  this Credit Agreement, as amended, supplemented or
           ---------
otherwise modified from time to time.

          "Applicable Margin": with respect to (a) Eurodollar Loans, 1% per
           -----------------
annum and (b) with respect to ABR Loans, 0% per annum.

          "Asset Transfer":  as defined in the recitals hereto.
           --------------

          "Assigned Interests": the rights under the Capital Call Agreements
           ------------------
which have been assigned to the Borrower pursuant to the Assignment of Capital
Call Rights and pledged to the Administrative Agent pursuant to the Security
Documents.

          "Assignee":  as defined in subsection 11.7(c).
           --------

          "Assignment of Capital Call Rights": the Assignment of Capital Call
           ---------------------------------
Rights, substantially in the form of Exhibit C-2, among Zhone, the Borrower and
the Administrative Agent, as the same may be amended, supplemented or otherwise
modified from time to time.

          "Borrower": AcquisitionCo (at all times prior to the Merger Date),
           --------
Premisys (at all times from the Merger Date to the Reorganization Date) or
LegacyCo (at all times from and after the Reorganization Date), as the context
shall require.

          "Borrowing Date": any Business Day specified in a Notice of Borrowing
           --------------
pursuant to subsection 2.2 or 3.2 as a date on which the Borrower requests the
Lenders to make Loans hereunder.

          "Business":  as defined in subsection 5.15(b).
           --------

          "Business Day": a day other than a Saturday, Sunday or other day on
           ------------
which commercial banks in New York City are authorized or required by law to
close; provided, however, that, with respect to matters relating to Eurodollar
       --------  -------
Loans, any day on which commercial banks in London, England are authorized or
required by law to close also shall not constitute a "Business Day".

          "Capital Call Agreement": the "Capital Call Agreements" described in
           ----------------------
the Assignment of Capital Call Rights, each substantially in the form of Exhibit
C-2 hereto (with such modifications as may be approved by the Administrative
Agent).
<PAGE>

                                                                               4

          "Capital Stock": any and all shares, interests (including, without
           -------------
limitation, membership interests in limited liability companies), participations
or other equivalents (however designated) of capital stock of a corporation, any
and all equivalent ownership interests in a Person (other than a corporation)
and any and all warrants or options to purchase any of the foregoing.

          "Cash Equivalents": (a) securities with maturities of one year or less
           ----------------
from the date of acquisition issued or fully guaranteed or insured by the United
States Government or any agency thereof, (b) certificates of deposit and
eurodollar time deposits with maturities of one year or less from the date of
acquisition and overnight bank deposits of any Lender or of any commercial bank
having capital and surplus in excess of $500,000,000, (c) repurchase obligations
of any Lender or of any commercial bank satisfying the requirements of clause
(b) of this definition, having a term of not more than 30 days with respect to
securities issued or fully guaranteed or insured by the United States
Government, (d) commercial paper of a domestic issuer rated at least A-2 by
Standard and Poor's Rating Group ("S&P") or P-2 by Moody's Investors Service,
                                   ---
Inc. ("Moody's"), (e) securities with maturities of one year or less from the
       -------
date of acquisition issued or fully guaranteed by any state, commonwealth or
territory of the United States, by any political subdivision or taxing authority
of any such state, commonwealth or territory or by any foreign government, the
securities of which state, commonwealth, territory, political subdivision,
taxing authority or foreign government (as the case may be) are rated at least A
by S&P or A by Moody's, (f) securities with maturities of one year or less from
the date of acquisition backed by standby letters of credit issued by any Lender
or any commercial bank satisfying the requirements of clause (b) of this
definition or (g) shares of money market mutual or similar funds which invest
exclusively in assets satisfying the requirements of clauses (a) through (f) of
this definition.

          "Closing Date": the date on which the conditions precedent set forth
           ------------
in subsection 6.1 shall be satisfied.

          "Code": the Internal Revenue Code of 1986, as amended from time to
           ----
time.

          "Collateral": all assets of the Credit Parties, now owned or
           ----------
hereinafter acquired, upon which a Lien is purported to be created by any
Security Document.

          "Collateral Substitution Date": the date upon which the requirements
           ----------------------------
specified in the proviso to subsection 11.2(c) have been satisfied.

          "Commitment": as to any Lender, its Acquisition Loan Commitment or its
           ----------
Term Loan Commitment, as the context shall require; as to all Lenders, the
"Commitments".
 -----------

          "Commitment Percentage": as to any Lender at any time, its Acquisition
           ---------------------
Loan Commitment Percentage or its Term Loan Commitment Percentage, as the
context shall require.

          "Commitment Period": the period from and including the date hereof to
           -----------------
but not including the Merger Date (or, if earlier, the date which is 180 days
following the date hereof).

          "Commonly Controlled Entity": an entity, whether or not incorporated,
           --------------------------
which is under common control with the Borrower within the meaning of Section
4001 of ERISA or is
<PAGE>

                                                                               5

part of a group which includes the Borrower and which is treated as a single
employer under Section 414 of the Code.

          "Consolidated Net Income" or "Consolidated Net Loss": for any fiscal
           -----------------------      ---------------------
period, the amount which, in conformity with GAAP, would be set forth opposite
the caption "net income" (or any like caption) or "net loss" (or any like
caption), as the case may be, on a consolidated statement of earnings of the
Borrower and its Subsidiaries for such fiscal period.

          "Contractual Obligation": as to any Person, any provision of any
           ----------------------
security issued by such Person or of any agreement, instrument or other
undertaking to which such Person is a party or by which it or any of its
property is bound.

          "Credit Documents": this Agreement, the Notes, the Security Documents,
           ----------------
the Premisys Escrow Agreement, the License Letters, the Capital Call Agreements
and the Assignment of Capital Call Rights.

          "Credit Parties": each of (a) the Borrower and each Subsidiary of the
           --------------
Borrower which is a party to a Credit Document, (b) prior to the Reorganization
Date, Zhone and (c) from and after the Merger Date, Premisys.

          "Default": any of the events specified in Section 9, whether or not
           -------
any requirement for the giving of notice, the lapse of time, or both, or any
other condition, has been satisfied.

          "Dollars" and "$": dollars in lawful currency of the United States of
           -------       -
America.

          "Domestic Subsidiary": any Subsidiary of the Borrower organized under
           -------------------
the laws of any jurisdiction within the United States.

          "EBITDA" for any period, the Consolidated Net Income or Consolidated
           ------
Net Loss, as the case may be, for such period, after restoring thereto amounts
deducted for (a) depreciation and amortization (including write-offs or write-
downs of amortizable and depreciable items) for such period, (b) the amount of
interest expense of the Borrower and its Subsidiaries, determined on a
consolidated basis in accordance with GAAP, for such period on the aggregate
principal amount of their consolidated Indebtedness, (c) the amount of tax
expense of the Borrower and its Subsidiaries, determined on a consolidated basis
in accordance with GAAP, for such period, (d) non-cash write-offs of acquired
in-process research and development expenses for such period and (e) non-cash
restructuring charges and reserves for such period.

          "Environmental Laws": any and all foreign, Federal, state, local or
           ------------------
municipal laws, rules, orders, regulations, statutes, ordinances, codes,
decrees, requirements of any Governmental Authority or other Requirements of Law
(including common law) regulating, relating to or imposing liability or
standards of conduct concerning protection of human health or the environment,
as now or may at any time hereafter be in effect.

          "ERISA": the Employee Retirement Income Security Act of 1974, as
           -----
amended from time to time.
<PAGE>

                                                                               6

          "Eurocurrency Reserve Requirements": for any day as applied to a
           ---------------------------------
Eurodollar Loan, the aggregate (without duplication) of the rates (expressed as
a decimal fraction) of reserve requirements in effect on such day (including,
without limitation, basic, supplemental, marginal and emergency reserves under
any regulations of the Board of Governors of the Federal Reserve System or other
Governmental Authority having jurisdiction with respect thereto) dealing with
reserve requirements prescribed for eurocurrency funding (currently referred to
as "Eurocurrency Liabilities" in Regulation D of such Board) maintained by a
member bank of such System.

          "Eurodollar Base Rate": the rate per annum determined by the
           --------------------
Administrative Agent at approximately 11:00 a.m. (London time) on the date which
is two Business Days prior to the beginning of the relevant Interest Period (as
specified in the applicable Notice of Borrowing) by reference to the "British
Bankers' Association Interest Settlement Rates" for deposits in Dollars (as set
forth by any service selected by the Administrative Agent which has been
nominated by the British Bankers' Association as an authorized information
vendor for the purpose of displaying such rates) for a period equal to such
Interest Period (rounded, if necessary, upward to the nearest whole multiple of
1/16th of 1%); provided that, to the extent that an interest rate is not
               --------
ascertainable pursuant to the foregoing provisions of this definition, the
"Eurodollar Base Rate" shall be the interest rate per annum determined by the
Administrative Agent to be the average (rounded, if necessary, upward to the
nearest whole multiple of 1/16th of 1% per annum, if such average is not such a
multiple) of the rates per annum at which deposits in Dollars are offered for
such relevant Interest Period to major banks in the London interbank market in
London, England by Credit Suisse First Boston at approximately 11:00 a.m.
(London time) on the date which is two Business Days prior to the beginning of
such Interest Period.

          "Eurodollar Loans": Loans the rate of interest applicable to which is
           ----------------
based upon the Eurodollar Rate.

          "Eurodollar Rate": with respect to each day during each Interest
           ---------------
Period pertaining to a Eurodollar Loan, a rate per annum determined for such day
in accordance with the following formula (rounded upward to the nearest 1/100th
of 1%):

                             Eurodollar Base Rate
                   ---------------------------------------
                   1.00 - Eurocurrency Reserve Requirements

          "Event of Default": any of the events specified in Section 9, provided
           ----------------                                             --------
that any requirement for the giving of notice, the lapse of time, or both, or
any other condition, has been satisfied.

          "Excess Cash Flow": for any fiscal year of the Borrower, EBITDA of the
           ----------------
Borrower for such fiscal year, minus (without duplication) (a) the sum of (i)
                               -----
the aggregate amount of expenditures during such fiscal year in respect of the
purchase or other acquisition by the Borrower and its Subsidiaries of fixed or
capital assets, (ii) any increase in Net Working Capital during such fiscal
year, (iii) the aggregate amount of cash income taxes paid by the Borrower and
its Subsidiaries during such fiscal year (including, without limitation, the
aggregate amount paid in cash during such fiscal year to Affiliates in reliance
upon the provisions of the proviso to subsection 8.8), (iv) the aggregate amount
of interest expense of the Borrower and its Subsidiaries, determined on a
consolidated basis in accordance with GAAP, for such fiscal year on the
aggregate principal amount of their consolidated Indebtedness and (v) all
<PAGE>

                                                                               7

prepayments of the Term Loans (but not the Acquisition Loans) during such fiscal
year plus (b) decreases in Net Working Capital during such fiscal year. As used
     ----
in this definition, the term "Net Working Capital" shall mean, at any date, the
                              -------------------
amount equal to the current assets of the Borrower and its Subsidiaries at such
date (as determined on a consolidated basis in accordance with GAAP) minus
current liabilities of the Borrower and its Subsidiaries at such date (as
determined on a consolidated basis in accordance with GAAP). Notwithstanding
anything to the contrary contained herein, for purposes of calculating Excess
Cash Flow, "EBITDA" shall not include the proceeds of asset sales permitted by
Section 8.6(i) to the extent that the net proceeds received by the Borrower and
its Subsidiaries since the Closing Date on account thereof does not exceed
$18,000,000 in the aggregate.

          "Federal Funds Effective Rate" shall mean, for any day, the weighted
           ----------------------------
average of the rates on overnight federal funds transactions with members of the
Federal Reserve System arranged by federal funds brokers, as published on the
next succeeding Business Day by the Federal Reserve Bank of New York, or, if
such rate is not so published for any day which is a Business Day, the average
of the quotations for the day of such transactions received by the
Administrative Agent from three federal funds brokers of recognized standing
selected by it.

          "Financing Lease": any lease of property, real or personal, the
           ---------------
obligations of the lessee in respect of which are required in accordance with
GAAP to be capitalized on a balance sheet of the lessee.

          "Foreign Pledge Agreement": each pledge agreement (or analogous
           ------------------------
document), which pledge agreement (or analogous document) shall be in form and
substance reasonably satisfactory to the Administrative Agent, pursuant to which
the Borrower or any of its Domestic Subsidiaries purports to grant a Lien on all
or any portion of the Capital Stock of any Foreign Subsidiary, as the same may
be amended, supplemented or otherwise modified from time to time.

          "Foreign Subsidiary": any Subsidiary of the Borrower organized under
           ------------------
the laws of any jurisdiction outside the United States of America.

          "GAAP": generally accepted accounting principles in the United States
           ----
of America as in effect from time to time; provided that, for purposes of
                                           --------
determining compliance with the provisions of subsection 8.1, "GAAP" shall mean
generally accepted accounting principles in the United States of America as in
effect on June 25, 1999.

          "Governmental Authority": any nation or government, any state or other
           ----------------------
political subdivision thereof and any entity exercising executive, legislative,
judicial, regulatory or administrative functions of or pertaining to government.

          "Granting Lender":  as defined in subsection 11.7(h).
           ---------------

          "Guarantee Obligation": as to any Person (the "guaranteeing person"),
           --------------------                          -------------------
any obligation of (a) the guaranteeing person or (b) another Person (including,
without limitation, any bank under any letter of credit) to induce the creation
of which the guaranteeing person has issued a reimbursement, counterindemnity or
similar obligation, in either case guaranteeing or in effect guaranteeing any
Indebtedness, leases, dividends or other obligations (the "primary
                                                           -------
<PAGE>

                                                                               8

obligations") of any other third Person (the "primary obligor") in any manner,
-----------                                   ---------------
whether directly or indirectly, including, without limitation, any obligation of
the guaranteeing person, whether or not contingent, (i) to purchase any such
primary obligation or any property constituting direct or indirect security
therefor, (ii) to advance or supply funds (1) for the purchase or payment of any
such primary obligation or (2) to maintain working capital or equity capital of
the primary obligor or otherwise to maintain the net worth or solvency of the
primary obligor, (iii) to purchase property, securities or services primarily
for the purpose of assuring the owner of any such primary obligation of the
ability of the primary obligor to make payment of such primary obligation or
(iv) otherwise to assure or hold harmless the owner of any such primary
obligation against loss in respect thereof; provided, however, that the term
                                            --------  -------
Guarantee Obligation shall not include endorsements of instruments for deposit
or collection in the ordinary course of business. The amount of any Guarantee
Obligation of any guaranteeing person shall be deemed to be the lower of (a) an
amount equal to the stated or determinable amount of the primary obligation in
respect of which such Guarantee Obligation is made and (b) the maximum amount
for which such guaranteeing person may be liable pursuant to the terms of the
instrument embodying such Guarantee Obligation, unless such primary obligation
and the maximum amount for which such guaranteeing person may be liable are not
stated or determinable, in which case the amount of such Guarantee Obligation
shall be such guaranteeing person's maximum reasonably anticipated liability in
respect thereof as determined by the Borrower in good faith.

          "Guarantor": each Person who guarantees the obligations of the
           ---------
Borrower under this Agreement (including, without limitation, after the Merger
Date and subject to Section 7.10, each Domestic Subsidiary of the Borrower).

          "Indebtedness": of any Person at any date, (a) all indebtedness of
           ------------
such Person for borrowed money or for the deferred purchase price of property or
services (other than current trade liabilities incurred in the ordinary course
of business and payable in accordance with customary practices), (b) any other
indebtedness of such Person which is evidenced by a note, bond, debenture or
similar instrument, (c) all obligations of such Person under Financing Leases,
(d) all obligations of such Person in respect of acceptances issued or created
for the account of such Person and (e) all liabilities secured by any Lien on
any property owned by such Person even though such Person has not assumed or
otherwise become liable for the payment thereof.

          "Initial Collateral Agreement": the Guarantee and Collateral
           ----------------------------
Agreement, substantially in the form of Exhibit D-1 hereto, made by Zhone and
certain of its Subsidiaries in favor of the Administrative Agent, as the same
may be amended, supplemented or otherwise modified from time to time.

          "Insolvency": with respect to any Multiemployer Plan, the condition
           ----------
that such Plan is insolvent within the meaning of Section 4245 of ERISA.

          "Insolvent":  pertaining to a condition of Insolvency.
           ---------

          "Interest Expense": for any period, the amount equal to the interest
           ----------------
expense (both expensed and capitalized) of the Borrower and its Subsidiaries,
determined on a consolidated basis in accordance with GAAP, for such period on
the aggregate principal amount of their consolidated Indebtedness.
<PAGE>

                                                                               9

          "Interest Payment Date": (a) as to any ABR Loan, the last Business Day
           ---------------------
of each March, June, September and December, (b) as to any Eurodollar Loan
having an Interest Period of three months or less, the last day of such Interest
Period and (c) as to any Eurodollar Loan having an Interest Period longer than
three months, each day which is three months, or a whole multiple thereof, after
the first day of such Interest Period (or, if such day is not a Business Day,
the next succeeding Business Day) and the last day of such Interest Period.

          "Interest Period": with respect to any Eurodollar Loan: (a) initially,
           ---------------
the period commencing on the borrowing or conversion date, as the case may be,
with respect to such Eurodollar Loan and ending one, two, three, six or (if
available to all Lenders) nine months thereafter, as selected by the Borrower in
its Notice of Borrowing given with respect thereto; and (b) thereafter, each
period commencing on the last day of the next preceding Interest Period
applicable to such Eurodollar Loan and ending one, two, three or six or (if
available to all Lenders) nine months thereafter, as selected by the Borrower by
irrevocable notice to the Administrative Agent not less than three Business Days
prior to the last day of the then current Interest Period with respect thereto;

provided that, all of the foregoing provisions relating to Interest Periods are
--------
subject to the following:

               (1)    if any Interest Period would otherwise end on a day that
          is not a Business Day, such Interest Period shall be extended to the
          next succeeding Business Day unless the result of such extension would
          be to carry such Interest Period into another calendar month in which
          event such Interest Period shall end on the immediately preceding
          Business Day;

               (2)    any Interest Period that would otherwise extend beyond the
          Maturity Date shall end on the Maturity Date;

               (3)    any Interest Period that begins on the last Business Day
          of a calendar month (or on a day for which there is no numerically
          corresponding day in the calendar month at the end of such Interest
          Period) shall end on the last Business Day of a calendar month;

               (4)    the Borrower shall select Interest Periods so as not to
          require a payment or prepayment of any Eurodollar Loan during an
          Interest Period for such Loan; and

               (5)    no Interest Period applicable to an Acquisition Loan shall
          be longer than one month.

          "Investors":  the collective reference to the Persons (other than
           ---------
Zhone) who are parties to the Capital Call Agreements; each, an "Investor."
                                                                 ---------
          "LegacyCo": as defined in the recitals hereto.
           --------
<PAGE>

                                                                              10

          "LegacyCo Cash Collateral Agreement": the Cash Collateral Agreement,
           ----------------------------------
substantially in the form of Exhibit G, made by LegacyCo in favor of the
Administrative Agent, as the same may be amended, supplemented or otherwise
modified from time to time.

          "Lenders": the collective reference to the Acquisition Lenders and the
           -------
Term Loan Lenders.

          "License Letter": a letter agreement, substantially in the form of
           --------------
Exhibit I hereto, duly executed and delivered by each Affiliate of the Borrower
in accordance with the provisions of subsection 8.6(f).

          "Lien": any mortgage, pledge, hypothecation, assignment, deposit
           ----
arrangement, encumbrance, lien (statutory or other), charge or other security
interest or any preference, priority or other security agreement or preferential
arrangement of any kind or nature whatsoever (including, without limitation, any
conditional sale or other title retention agreement and any Financing Lease
having substantially the same economic effect as any of the foregoing).

          "Loan": any Acquisition Loan or any Term Loan, as the context shall
           ----
require.

          "Majority Lenders": at any time, Lenders having Commitment Percentages
           ----------------
which aggregate more than 50% of the sum of the Aggregate Term Loan Commitment
then in effect (or, after the Term Loan Borrowing Date, the aggregate
outstanding principal amount of Term Loans), the portion of the Aggregate
Acquisition Loan Commitment which remains unutilized and the aggregate
outstanding principal amount of Acquisition Loans.

          "Material Adverse Effect": a material adverse effect upon (a) the
           -----------------------
consummation of the Transaction, (b) the business, assets, property or condition
(financial or otherwise) of the Borrower and its Subsidiaries taken as a whole,
(c) the validity or enforceability of any of the Credit Documents or the rights
and remedies of the Administrative Agent and the Lenders thereunder, (d) prior
to the Collateral Substitution Date, the right or ability of the Administrative
Agent to draw upon the Assigned Interests or (e) prior to the Collateral
Substitution Date, the ability of any Investor to perform its respective
obligations under the Capital Call Agreement provided by it, unless another
Investor shall have assumed the obligations of the relevant Investor under the
Capital Call Agreement to which it is a party pursuant to documentation which is
in form and substance reasonably satisfactory to the Administrative Agent.

          "Material Environmental Amount": an amount payable by the Borrower
           -----------------------------
and/or its Subsidiaries in excess of $500,000 for remedial costs, compliance
costs, compensatory damages, punitive damages, fines, penalties or any
combination thereof.

          "Materials of Environmental Concern": any gasoline or petroleum
           ----------------------------------
(including crude oil or any fraction thereof) or petroleum products or any
hazardous or toxic substances, materials or wastes, defined or regulated as such
in or under any Environmental Law, including, without limitation, asbestos,
polychlorinated biphenyls and urea-formaldehyde insulation.

          "Maturity Date": November 28, 2004.
           -------------

          "Merger":  as defined in the recitals hereto.
           ------
<PAGE>

                                                                              11

          "Merger Agreement":  as defined in the recitals hereto.
           ----------------

          "Merger Date":  the date upon which the Merger is consummated.
           -----------

          "Multiemployer Plan":  a Plan which is a multiemployer plan as defined
           ------------------
in Section 4001(a)(3) of ERISA.

          "Net Proceeds": with respect to any Net Proceeds Event, (a) the gross
           ------------
cash consideration, and all cash proceeds (as and when received) of non-cash
consideration (including, without limitation, any such cash proceeds in the
nature of principal and interest payments on account of promissory notes or
similar obligations), received by Zhone and its Subsidiaries in connection with
such Net Proceeds Event, minus (b) the sum, without duplication, of (i) any
taxes which are paid or actually payable to any federal, state, local or foreign
taxing authority by the Borrower and its Subsidiaries and are directly
attributable to the receipt of such Net Proceeds, (ii) the amount of fees and
commissions (including reasonable investment banking fees payable to Persons
other than Affiliates of the Borrower), legal, accounting, consulting, survey,
title and recording tax expenses and other costs and expenses directly incident
to such Net Proceeds Event which are paid or payable by the Borrower and its
Subsidiaries, (iii) the amount of such net cash proceeds which are attributable
to (and payable to) minority interests, (iv) the amount of any reserve
reasonably maintained by the Borrower and its Subsidiaries with respect to
indemnification obligations owing pursuant to the definitive documentation
pursuant to which the Net Proceeds Event is consummated (with any unused portion
of such reserve to constitute Net Proceeds on the date upon which the
indemnification obligations terminate) and (v) the amount of Indebtedness (other
than intercompany Indebtedness), if any, which is required to be repaid at the
time or as a result of such Net Proceeds Event out of the proceeds thereof.

          "Net Proceeds Event": (a) the incurrence by the Borrower or any of its
           ------------------
Subsidiaries of any Indebtedness (other than Indebtedness permitted pursuant to
subsection 9.2, as in effect on the date hereof); (b) the issuance or sale of
any equity securities by Zhone, the Borrower or any of its Subsidiaries to any
Person (other than any proceeds of capital calls made pursuant to the Stock
Purchase Agreements) in (in the case of Zhone only) a public or other widely
distributed offering, other than (i) in the case of the Borrower or any of its
Subsidiaries, the issuance or sale of any such equity securities to the Borrower
or any of its Subsidiaries, (ii) the issuance of Capital Stock upon the sale or
exercise of stock options, (iii) the issuance and sale of Capital Stock under
employee stock purchase plans, (iv) the issuance and sale of Capital Stock
and/or stock options under employee stock ownership and incentive plans and
similar programs or individual arrangements; provided that any issuance or sale
of equity securities by Zhone which is consummated on or after the Collateral
Substitution Date shall be deemed not to constitute a "Net Proceeds Event"; (c)
the sale, transfer or other disposition by the Borrower or any of its
Subsidiaries of any real or personal, tangible or intangible, property
(including, without limitation, any Capital Stock, but other than (x) inventory
sold, transferred or otherwise disposed of in the ordinary course of business or
pursuant to the Asset Transfer, (y) other inventory sold in reliance upon the
provisions of subsection 8.6(h) and (z) manufacturing assets sold in reliance
upon the provisions of subsection 8.6(i)) of the Borrower or such Subsidiary to
any Person (other than to the Borrower or any of its Subsidiaries); and (d) the
recovery by the Borrower of amounts owing to it under property insurance
policies.
<PAGE>

                                                                              12

          "Non-Excluded Taxes":  as defined in subsection 4.14(a).
           ------------------

          "Note":  an Acquisition Note or a Term Loan Note, as the context shall
           ----
require; collectively, the "Notes."
                            -----

          "Notice of Borrowing": with respect to (a) any borrowing of Loans, a
           -------------------
Notice of Borrowing (Drawings), substantially in the form of Exhibit K-1, (b)
any continuation of Eurodollar Loans, a Notice of Borrowing (Continuations),
substantially in the form of Exhibit K-2 and (c) any conversion from or to
Eurodollar Loans, a Notice of Borrowing (Conversions), substantially in the form
of Exhibit K-3 hereto.

          "Offer to Purchase": the Offer to Purchase, dated as of October 27,
           -----------------
1999, of AcquisitionCo relating to the Tender Offer, as amended, supplemented or
modified to the date hereof and as the same may be further amended, supplemented
or otherwise modified from time to time in accordance with the terms hereof;

          "Participant":  as defined in subsection 11.7(b).
           -----------

          "PBGC":  the Pension Benefit Guaranty Corporation established pursuant
           ----
to Subtitle A of Title IV of ERISA.

          "Person": an individual, partnership, corporation, business trust,
           ------
joint stock company, trust, unincorporated association, joint venture,
Governmental Authority or other entity of whatever nature.

          "Plan": at a particular time, any employee benefit plan which is
           ----
covered by ERISA and in respect of which the Borrower or a Commonly Controlled
Entity is (or, if such plan were terminated at such time, would under Section
4069 of ERISA be deemed to be) an "employer" as defined in Section 3(5) of
ERISA.

          "Premisys":  as defined in the recitals hereto.
           --------

          "Premisys Escrow Agreement": the Escrow Agreement, substantially in
           -------------------------
the form of Exhibit E hereto, among Premisys, the Administrative Agent and
Credit Suisse First Boston (as escrow agent), as the same may be amended,
supplemented or otherwise modified from time to time.

          "Prime Rate" shall mean the rate of interest per annum publicly
           ----------
announced from time to time by the Administrative Agent as its prime rate in
effect at its principal office in New York City.

          "Properties":  as defined in subsection 5.15(a).
           ----------

          "Register":  as defined in subsection 11.7(d).
           --------

          "Regulation U":  Regulation U of the Board of Governors of the Federal
           ------------
Reserve System as in effect from time to time.
<PAGE>

                                                                              13

          "Reorganization": with respect to any Multiemployer Plan, the
           --------------
condition that such plan is in reorganization within the meaning of Section 4241
of ERISA.

          "Reorganization Date": the date upon which the Term Loans are assumed
           -------------------
by LegacyCo pursuant to the Asset Transfer and in accordance with the provisions
of subsection 8.17 hereof.

          "Reportable Event": any of the events set forth in Section 4043(b) of
           ----------------
ERISA, other than those events as to which the thirty day notice period is
waived under subsections .13, .14, .16, .18, .19 or .20 of PBGC Reg. (S) 2615.

          "Requirement of Law": as to any Person, the Certificate of
           ------------------
Incorporation and By-Laws or other organizational or governing documents of such
Person, and any law, treaty, rule or regulation or determination of an
arbitrator or a court or other Governmental Authority, in each case applicable
to or binding upon such Person or any of its property or to which such Person or
any of its property is subject.

          "Responsible Officer": the chief executive officer and the president
           -------------------
of the Borrower or, with respect to financial matters, the chief financial
officer of the Borrower.

          "Security Documents": the collective reference to: (a) at any date
           ------------------
prior to the Reorganization Date, the AcquisitionCo Cash Collateral Agreement,
the Initial Collateral Agreement and any Foreign Pledge Agreements; or (b) at
any date which is on or after the Reorganization Date, the Subsequent Collateral
Agreement, the LegacyCo Cash Collateral Agreement and any Foreign Pledge
Agreements.

          "Shares":  as defined in the recitals hereto.
           ------

          "Single Employer Plan":  any Plan which is covered by Title IV of
           --------------------
ERISA, but which is not a Multiemployer Plan.

          "SPC":  as defined in subsection 11.7(h).
           ---

          "Stock Purchase Agreements":  as defined in the Assignment of Capital
           -------------------------
Call Rights.

          "Subsequent Collateral Agreement": the Guarantee and Collateral
           -------------------------------
Agreement, substantially in the form of Exhibit F, made by Premisys and certain
of its Subsidiaries in favor of the Administrative Agent, as the same may be
amended, supplemented or otherwise modified from time to time.

          "Subsidiary": as to any Person, a corporation, partnership or other
           ----------
entity of which shares of stock or other ownership interests having ordinary
voting power (other than stock or such other ownership interests having such
power only by reason of the happening of a contingency) to elect a majority of
the board of directors or other managers of such corporation, partnership or
other entity are at the time owned, or the management of which is otherwise
controlled, directly or indirectly through one or more intermediaries, or both,
by such Person.
<PAGE>

                                                                              14

Unless otherwise qualified, all references to a "Subsidiary" or to
"Subsidiaries" in this Agreement shall refer to a Subsidiary or Subsidiaries of
the Borrower. For purposes hereof, a Subsidiary shall be deemed to be "wholly
owned" by the Borrower despite the ownership by a third-party of a de minimis
amount of shares of such Subsidiary in order to comply with local Requirements
of Law (such as directors' qualifying shares or ownership by a local resident).

          "Substitute Collateral":  as defined in subsection 11.2(c).
           ---------------------

          "Tender Offer":  as defined in the recitals hereto.
           ------------

          "Tender Offer Documents" shall be the collective reference to (a) the
           ----------------------
tender offer statement on Schedule 14D-1, dated October 27, 1999, filed by
AcquisitionCo with the SEC pursuant to Section 14(d)(1) of the Exchange Act,
together with all exhibits thereto, including the Offer to Purchase, the
solicitation/recommendation statement on Schedule 14D-9, dated October 27, 1999,
filed by Premisys pursuant to Section 14(d)(4) of the Exchange Act, in each
case, as amended, supplemented or otherwise modified from time to time, and (b)
the Offer to Purchase.

          "Tendered Shares":  as defined in the recitals hereto.
           ---------------

          "Term Loan Borrowing Date":  as defined in Section 2.1.
           ------------------------

          "Term Loan Commitment": as to any Term Loan Lender, its obligation to
           --------------------
make its Term Loan to the Borrower hereunder in an aggregate principal amount
not to exceed the amount set forth opposite such Term Loan Lender's name on
Schedule I under the heading "Term Loan Commitment".

          "Term Loan Commitment Percentage": as to any Term Loan Lender at any
           -------------------------------
time, the percentage which such Term Loan Lender's Term Loan Commitment then
constitutes of the Aggregate Term Loan Commitment (or, at any time after the
Term Loan Borrowing Date, the percentage which the aggregate principal amount of
such Term Loan Lender's Term Loans then outstanding constitutes of the aggregate
principal amount of the Term Loans then outstanding).

          "Term Loan Lender": each bank or other financial institution holding a
           ----------------
Term Loan Commitment hereunder (or, after the Term Loan Borrowing Date and
subject to the provisions of subsection 11.7(d), holding any Term Loans
hereunder); collectively, the "Term Loan Lenders".
                               -----------------

          "Term Loan":  as defined in subsection 2.1.
           ---------

          "Term Loan Note":  as defined in subsection 4.1(e).
           --------------

          "Tranche": the collective reference to Eurodollar Loans the then
           -------
current Interest Periods with respect to all of which begin on the same date and
end on the same later date (whether or not such Loans shall originally have been
made on the same day); Tranches may be identified as "Eurodollar Tranches".
                                                      -------------------

          "Transaction":  as defined in the recitals hereto.
           -----------
<PAGE>

                                                                              15

          "Transferee":  as defined in subsection 11.7(h).
           ----------

          "Type":  as to any Loan, its nature as an ABR Loan or a Eurodollar
           ----
Loan.

          "Uniform Customs": the Uniform Customs and Practice for Documentary
           ---------------
Credits (1993 Revision), International Chamber of Commerce Publication No. 500,
as the same may be amended from time to time.

          "Zhone":  as defined in the recitals hereto.
           -----

          "Zhone Subordinated Note": the subordinated promissory note,
           -----------------------
substantially in the form of Exhibit L, evidencing certain Indebtedness owing by
AcquisitionCo (or, after the Merger Date, Premisys) to Zhone, as the same may be
amended, supplemented or otherwise modified from time to time in accordance with
the terms hereof.

          1.2    Other Definitional Provisions. (a) Unless otherwise specified
                 -----------------------------
therein, all terms defined in this Agreement shall have the defined meanings
when used in any Notes or any certificate or other document made or delivered
pursuant hereto.

          (b)    As used herein and in any Notes, and any certificate or other
     document made or delivered pursuant hereto, accounting terms relating to
     the Borrower and its Subsidiaries not defined in subsection 1.1 and
     accounting terms partly defined in subsection 1.1, to the extent not
     defined, shall have the respective meanings given to them under GAAP.

          (c)    The words "hereof", "herein" and "hereunder" and words of
     similar import when used in this Agreement shall refer to this Agreement as
     a whole and not to any particular provision of this Agreement, and Section,
     subsection, Schedule and Exhibit references are to this Agreement unless
     otherwise specified.

          (d)    The meanings given to terms defined herein shall be equally
     applicable to both the singular and plural forms of such terms.

             SECTION 2.  AMOUNT AND TERMS OF TERM LOAN COMMITMENTS

          2.1    Term Loans. Subject to the terms and conditions hereof, each
                 ----------
Term Lender severally agrees to make a term loan (a "Term Loan") to the Borrower
                                                     ---------
on any single date (the "Term Loan Borrowing Date") during the period from the
                         ------------------------
Closing Date through and including the Merger Date (and, in any event, on or
prior to February 15, 2000) in an amount not to exceed the amount of the Term
Loan Commitment of such Term Loan Lender then in effect. The Term Loans may from
time to time be (a) Eurodollar Loans, (b) ABR Loans or (c) a combination
thereof, as determined by the Borrower and notified to the Administrative Agent
in accordance with subsections 2.2 and 4.6.

          2.2    Procedure for Term Loan Borrowing. The Borrower shall give the
                 ---------------------------------
Administrative Agent its irrevocable Notice of Borrowing (which notice must be
received by the Administrative Agent prior to 1:00 P.M., New York City time, (a)
three Business Days prior to the Term Loan Borrowing Date, if all or any part of
the requested Term Loans are to be initially Eurodollar Loans or (b) one
Business Day prior to the Term Loan Borrowing Date, otherwise) requesting that
the Term Loan Lenders make the Term Loans on the Term Loan Borrowing Date
<PAGE>

                                                                              16

and specifying (i) the amount to be borrowed, (ii) the requested Borrowing Date,
(iii) whether the borrowing is to be of Eurodollar Loans, ABR Loans or a
combination thereof and (iv) if the borrowing is to be entirely or partly of
Eurodollar Loans, the amount of such Type of Loan and the length of the initial
Interest Period therefor. Upon receipt of such Notice of Borrowing, the
Administrative Agent shall promptly notify each Term Loan Lender thereof. Each
Term Loan Lender will make the amount of its pro rata share of the Term Loans
available to the Administrative Agent for the account of the Borrower at the
office of the Administrative Agent specified in subsection 11.3 prior to 11:00
A.M., New York City time, on the Term Loan Borrowing Date in funds immediately
available to the Administrative Agent. Such Term Loans will then be made
available to the Borrower by the Administrative Agent transferring to the
account directed by the Borrower (which account need not be maintained by the
Administrative Agent) with the aggregate of the amounts made available to the
Administrative Agent by the Term Loan Lenders and in like funds as received by
the Administrative Agent.

          2.3  Amortization of Term Loans.  (a)  The Borrower shall repay the
               --------------------------
Term Loans on each date set forth below (or, if such date is not a Business Day,
on the immediately preceding Business Day) by the percentage of the aggregate
principal amount of Term Loans borrowed on the Term Loan Borrowing Date as set
forth below:

<TABLE>
<CAPTION>
============================================================================
         Date                                 Amount
<S>                       <C>
  December 31, 1999                                           $            0
----------------------    --------------------------------------------------
    March 31, 2000                                                         0

    June 30, 2000                                                          0

  September 30, 2000                                                    5.00%

  December 31, 2000                                                     5.00%
----------------------    --------------------------------------------------
    March 31, 2001                                                      3.75%

    June 30, 2001                                                       3.75%

  September 30, 2001                                                    3.75%

  December 31, 2001                                                     3.75%
----------------------    --------------------------------------------------
    March 31, 2002                                                      6.25%

    June 30, 2002                                                       6.25%

  September 30, 2002                                                    6.25%

  December 31, 2002                                                     6.25%
----------------------    --------------------------------------------------
</TABLE>
<PAGE>

                                                                              17

<TABLE>
<S>                       <C>
----------------------    --------------------------------------------------
    March 31, 2003                                                      6.25%

    June 30, 2003                                                       6.25%

  September 30, 2003                                                    6.25%

  December 31, 2003                                                     6.25%
----------------------    --------------------------------------------------
    March 31, 2004                                                      6.25%

    June 30, 2004                                                       6.25%

  September 30, 2004                                                    6.25%
============================================================================
</TABLE>

          (b)  The Borrower shall repay any then-outstanding Term Loans on the
Maturity Date.

          2.4  Use of Proceeds of Term Loans. The proceeds of the Term Loans
               ------------------------------
shall be utilized by the Borrower only (a) to finance a portion of the
consideration paid to tendering shareholders of Premisys on account of the
Tendered Shares or otherwise to acquire Shares, (b) to refinance any such
consideration which is paid out of equity of the Borrower or with the proceeds
of loans from Zhone and (c) to pay any fees and expenses relating to the
Transaction.

     SECTION 3  AMOUNT AND TERMS OF ACQUISITION LOAN COMMITMENTS

          3.1  Acquisition Term Loans.  Subject to the terms and conditions
               ----------------------
hereof, each Acquisition Lender severally agrees to make term loans (each, an
"Acquisition Loan") to the Borrower from time to time during the Commitment
-----------------
Period in an aggregate principal amount not to exceed the amount of the
Acquisition Loan Commitment of such Acquisition Lender then in effect.  The
Acquisition Loans may from time to time be (a) Eurodollar Loans, (b) ABR Loans
or (c) a combination thereof, as determined by the Borrower and notified to the
Administrative Agent in accordance with subsections 3.2 and 4.6.

          3.2  Procedure for Acquisition Loan Borrowing.  (a)  The Borrower may
               ----------------------------------------
borrow under the Aggregate Acquisition Loan Commitment during the Commitment
Period on any Business Day, provided that the Borrower shall give the
                            --------
Administrative Agent irrevocable notice (which notice must be received by the
Administrative Agent prior to 1:00 P.M., New York City time, (x) three Business
Days prior to the requested Borrowing Date, if all or any part of the requested
Acquisition Loans are to be initially Eurodollar Loans or (y) one Business Day
prior to the requested Borrowing Date, otherwise), specifying (i) the amount to
be borrowed, (ii) the requested Borrowing Date, (iii) whether the borrowing is
to be of Eurodollar Loans, ABR Loans or a combination thereof and (iv) if the
borrowing is to be entirely or partly of Eurodollar Loans, the amount of such
Type of Loan and the length of the initial Interest Period therefor.  Each
borrowing under the Aggregate Acquisition Loan Commitment shall be in an amount
equal to $2,000,000 or a whole multiple of $1,000,000 in excess thereof (or, in
the case of borrowings of ABR Loans when the then unutilized amount of the
Aggregate Acquisition Loan Commitment is less than $2,000,000, such lesser
amount).  Upon receipt of any such notice from the Borrower, the Administrative
Agent shall promptly notify each Acquisition Lender thereof.  Each
<PAGE>

                                                                              18

Acquisition Lender will make the amount of its pro rata share of each borrowing
available to the Administrative Agent for the account of the Borrower at the
office of the Administrative Agent specified in subsection 11.3 prior to 11:00
A.M., New York City time, on the Borrowing Date requested by the Borrower in
funds immediately available to the Administrative Agent. Such borrowing will
then be made available to the Borrower by the Administrative Agent crediting the
account of the Borrower on the books of such office with the aggregate of the
amounts made available to the Administrative Agent by the Acquisition Lenders
and in like funds as received by the Administrative Agent.

          (b)  Notwithstanding anything to the contrary contained herein, (i)
the Borrower may make not more than six borrowings under the Aggregate
Acquisition Loan Commitments and (ii) the Borrower may only borrow Acquisition
Loans on any day to the extent necessary to pay obligations described in
subsection 3.4 which are then due and payable.

          3.3  Maturity of Acquisition Loans.  The Acquisition Loans shall be
               -----------------------------
due and payable in a single installment on the Merger Date.

          3.4  Use of Proceeds of Acquisition Loans.  The proceeds of the
               ------------------------------------
Acquisition Loans shall be utilized by the Borrower only (a) to finance the
purchase of Shares (including shares which are issued pursuant to the Company
Option Agreement described in the Merger Agreement), (b) to pay any fees and
expenses relating to the Transaction and (c) to finance interest payable on
account of the Loans.

     SECTION 4.  PROVISIONS RELATING TO THE LOANS; FEES AND PAYMENTS

          4.1  Repayment of Loans; Evidence of Debt.  (a) The Borrower hereby
               ------------------------------------
unconditionally promises to pay to the Administrative Agent for the account of
each applicable Lender:

          (i)  the then unpaid principal amount of each Term Loan of each Term
     Loan Lender on the dates and in the amounts set forth in subsection 2.3 (or
     the then unpaid principal amount of such Term Loan, on any earlier date
     that the Term Loans become due and payable pursuant to Section 9); and

          (ii) the then unpaid principal amount of the Acquisition Loan of each
     Acquisition Lender on the Merger Date (or on any earlier date that the
     Acquisition Loans become due and payable pursuant to Section 9).

          The Borrower hereby further agrees to pay interest on the unpaid
principal amount of the Loans from time to time outstanding from the date hereof
until payment in full thereof at the rates per annum, and on the dates, set
forth in subsection 4.8.

          (b)  Each Lender shall maintain in accordance with its usual practice
     an account or accounts evidencing indebtedness of the Borrower to such
     Lender resulting from each Loan of such Lender from time to time, including
     the amounts of principal and interest payable and paid to such Lender from
     time to time under this Agreement.

          (c)  the Administrative Agent shall maintain the Register pursuant to
     subsection 11.7(d), and a subaccount therein for each Lender, in which
     shall be recorded
<PAGE>

                                                                              19

     (i) the amount of each Loan made hereunder, the Type thereof and each
     Interest Period applicable thereto, (ii) the amount of any principal or
     interest due and payable or to become due and payable from the Borrower to
     each Lender hereunder and (iii) both the amount of any sum received by the
     Administrative Agent hereunder from the Borrower and each applicable
     Lender's share thereof.

          (d)  The entries made in the Register and the accounts of each Lender
     maintained pursuant to subsection 4.1(b) shall, to the extent permitted by
     applicable law, be prima facie evidence of the existence and amounts of the
                        ----- -----
     obligations of the Borrower therein recorded; provided, however, that the
                                                   --------  -------
     failure of any Lender or the Administrative Agent to maintain the Register
     or any such account, or any error therein, shall not in any manner affect
     the obligation of the Borrower to repay (with applicable interest) the
     Loans made to the Borrower by such Lender in accordance with the terms of
     this Agreement.

          (e)  The Borrower agrees that, upon request of any Lender through the
     Administrative Agent, the Borrower will execute and deliver to such Lender
     (i) in the case of a Term Loan Lender, a promissory note of the Borrower
     evidencing the Term Loan of such Term Loan Lender, substantially in the
     form of Exhibit A with appropriate insertions as to date and principal
     amount (a "Term Loan Note") and (ii) in the case of an Acquisition Lender,
                --------------
     a promissory note of the Borrower evidencing the Acquisition Loans of such
     Acquisition Lender, substantially in the form of Exhibit B with appropriate
     insertions as to date and principal amount (an "Acquisition Note").
                                                     ----------------

          4.2  Commitment Fee.  The Borrower agrees to pay to the Administrative
               --------------
Agent for the account of each Lender a commitment fee for the period from and
including the date upon which this Agreement shall be executed and delivered by
each of the parties hereto to and including the Merger Date, computed at the
rate equal to 3/8 of 1% per annum on the average daily amount of the unutilized
portion of the Acquisition Loan Commitment and the Term Loan Commitment then in
effect for such Lender during the period for which payment is made.  Such
commitment fee shall be payable quarterly, in arrears, on the last Business Day
of each March, June, September and December and on the Merger Date or such
earlier date as the Aggregate Acquisition Loan Commitment shall terminate as
provided herein.

          4.3  Optional Prepayments.  The Borrower may at any time and from time
               --------------------
to time prepay the Acquisition Loans or (if no Acquisition Loans are then
outstanding) the Term Loans, in whole or in part, without premium or penalty,
upon at least three Business Days' (or, in the case of prepayments of ABR Loans,
one Business Day's) irrevocable notice to the Administrative Agent (which notice
must be received by the Administrative Agent prior to 1:00 P.M., New York City
time, on the date upon which such notice is due), specifying the date and amount
of prepayment and whether the prepayment is of Eurodollar Loans, ABR Loans or a
combination thereof, and, if of a combination thereof, the amount allocable to
each.  Upon receipt of any such notice, the Administrative Agent shall promptly
notify each affected Lender thereof. If any such notice is given, the amount
specified in such notice shall be due and payable on the date specified therein,
together with any amounts payable pursuant to subsection 4.15 and accrued
interest to such date on the amount prepaid. Partial prepayments of the Term
Loans shall be applied to the remaining installments of principal thereof in
such order as the Borrower shall specify. Amounts prepaid on account of the
Loans may not be reborrowed. Partial
<PAGE>

                                                                              20

prepayments shall be in an aggregate principal amount of $2,000,000 or a whole
multiple of $1,000,000 in excess thereof.

          4.4  Optional Termination or Reduction of Aggregate Acquisition Loan
               ---------------------------------------------------------------
Commitment.  The Borrower shall have the right, upon not less than five Business
----------
Days' notice to the Administrative Agent, to terminate or, from time to time,
reduce the unutilized portion of the Aggregate Acquisition Loan Commitment.  Any
such reduction shall be in an amount equal to $2,000,000 or a whole multiple of
$1,000,000 in excess thereof and shall reduce permanently the Aggregate
Acquisition Loan Commitment then in effect.

          4.5  Mandatory Prepayments.  (a)  The Borrower shall, as promptly as
               ---------------------
is practicable (and, in any event, within one Business Day following the receipt
thereof), repay the Loans by the amount equal to the aggregate amount of Net
Proceeds received from any Net Proceeds Event; provided that no such repayment
                                               --------
and reduction shall be due pursuant to this subsection 4.5(a) with respect to
any Net Proceeds Event on account of the recovery by the Borrower of amounts
owing to it under property insurance policies, except to the extent that either
(i) such recoveries exceed the reasonably estimated cost of replacing the
property on account of which such amounts were paid to the Borrower and its
Subsidiaries or (ii) the Borrower and its Subsidiaries are not diligently
proceeding with such replacement.  Any payments of the Loans made pursuant to
this subsection 4.5(a) shall be applied, first, to the prepayment of the
Acquisition Loans and, second, to the prepayment of the Term Loans, with such
prepayment of the Term Loans being applied ratably to the remaining installments
thereof.  Unless the Borrower otherwise elects, the application of prepayments
made pursuant to this subsection 4.5(a) shall be made, first, to ABR Loans and,
second, to Eurodollar Loans.  Amounts prepaid on account of the Loans may not be
reborrowed.

          (b)  The Borrower shall, immediately upon receipt thereof, repay the
     Loans by the amount equal to 100% of the gross proceeds received by it on
     account of capital calls under the Capital Call Agreements.  Any payments
     of the Loans made pursuant to this subsection 4.5(b) shall be applied in
     such manner as the Administrative Agent shall elect.

          4.6  Conversion and Continuation Options. (a)  The Borrower may elect
               -----------------------------------
from time to time to convert Eurodollar Loans to ABR Loans by delivering to the
Administrative Agent an irrevocable Notice of Borrowing (Conversion) by 1:00
P.M., New York City time, at least one Business Day prior to the requested date
of conversion; provided that any such conversion of Eurodollar Loans may only be
               --------
made on the last day of an Interest Period with respect thereto.  The Borrower
may elect from time to time to convert ABR Loans to Eurodollar Loans by
delivering to the Administrative Agent an irrevocable Notice of Borrowing by
1:00 P.M., New York City time, at least three Business Days' prior to the
requested conversion date.  Any such Notice of Borrowing (Conversion) with
respect to a conversion to Eurodollar Loans shall specify the length of the
initial Interest Period or Interest Periods therefor.  Upon receipt of any such
Notice of Borrowing (Conversion), the Administrative Agent shall promptly notify
each Lender thereof.  All or any part of outstanding Eurodollar Loans and ABR
Loans may be converted as provided herein, provided that (i) no Loan may be
                                           --------
converted into a Eurodollar Loan when any Event of Default has occurred and is
continuing and the Administrative Agent has or the Majority Lenders have
determined that such a conversion is not appropriate and (ii) no Term Loan may
be converted into a Eurodollar Loan after the date that is one month prior to
the Maturity Date.
<PAGE>

                                                                              21

          (i)  Any Eurodollar Loans may be continued as such upon the expiration
     of the then current Interest Period with respect thereto by the Borrower
     delivering to the Administrative Agent an irrevocable Notice of Borrowing
     (Continuation), in accordance with the applicable provisions of the term
     "Interest Period" set forth in subsection 1.1, setting forth (among other
     things) the length of the next Interest Period to be applicable to such
     Loans, provided that (i) no Loan may be continued as a Eurodollar Loan when
            --------
     any Event of Default has occurred and is continuing and the Administrative
     Agent has or the Majority Lenders have determined that such a continuation
     is not appropriate and (ii) no Term Loan may be continued as a Eurodollar
     Loan after the date that is one month prior to the Maturity Date and
     provided, further, that if the Borrower shall fail to give such notice or
     --------  -------
     if such continuation is not permitted such Loans shall be automatically
     converted to ABR Loans on the last day of such then expiring Interest
     Period.  Upon receipt of any such Notice of Borrowing (Continuation), the
     Administrative Agent shall promptly notify each Lender thereof.

          4.7  Minimum Amounts and Maximum Number of Tranches.  All borrowings,
               ----------------------------------------------
conversions and continuations of Loans hereunder and all selections of Interest
Periods hereunder shall be in such amounts and be made pursuant to such
elections so that, after giving effect thereto, the aggregate principal amount
of the Loans comprising each Eurodollar Tranche shall be equal to $2,000,000 or
a whole multiple of $1,000,000 in excess thereof.  In no event shall there be
more than 6 (or, prior to the Merger Date, 8) Eurodollar Tranches outstanding at
any time.

          4.8  Interest Rates and Payment Dates.  (a)  Each Eurodollar Loan
               --------------------------------
shall bear interest for each day during each Interest Period with respect
thereto at a rate per annum equal to the Eurodollar Rate determined for such day
plus the Applicable Margin with respect thereto.

          (b)  Each ABR Loan shall bear interest at a rate per annum equal to
      the ABR plus the Applicable Margin with respect thereto.

          (c)  If all or a portion of (i) any principal of any Loan, (ii) any
     interest payable thereon, (iii) any commitment fee or (iv) any other amount
     payable hereunder shall not be paid when due (whether at the stated
     maturity, by acceleration or otherwise), the principal of the Loans and any
     such overdue interest, commitment fee or other amount shall bear interest
     at a rate per annum which is (x) in the case of principal, the rate that
     would otherwise be applicable thereto pursuant to the foregoing provisions
     of this subsection plus 2% or (y) in the case of any such overdue interest,
     commitment fee or other amount, the rate described in paragraph (b) of this
     subsection plus 2%, in each case from the date of such non-payment until
     such overdue principal, interest, commitment fee or other amount is paid in
     full (as well after as before judgment).

          (d)  Interest shall be payable in arrears on each Interest Payment
     Date, provided that interest accruing pursuant to paragraph (c) of this
           --------
     subsection shall be payable from time to time on demand.

          4.9  Computation of Interest and Fees.  (a)  Commitment fees and,
               --------------------------------
whenever it is calculated on the basis of the Prime Rate, interest shall be
calculated on the basis of a 365- (or
<PAGE>

                                                                              22

366-, as the case may be) day year for the actual days elapsed; and, otherwise,
interest shall be calculated on the basis of a 360-day year for the actual days
elapsed. The Administrative Agent shall as soon as practicable notify the
Borrower and the affected Lenders of each determination of a Eurodollar Rate.
Any change in the interest rate on a Loan resulting from a change in the ABR or
the Eurocurrency Reserve Requirements shall become effective as of the opening
of business on the day on which such change becomes effective. The
Administrative Agent shall as soon as practicable notify the Borrower and the
affected Lenders of the effective date and the amount of each such change in
interest rate.

          (b)  Each determination of an interest rate by the Administrative
     Agent pursuant to any provision of this Agreement shall be conclusive and
     binding on the Borrower and the Lenders in the absence of manifest or
     demonstrable error. The Administrative Agent shall, at the request of the
     Borrower, deliver to the Borrower a statement showing the quotations used
     by the Administrative Agent in determining any interest rate pursuant to
     subsection 4.9(a).

          4.10 Inability to Determine Interest Rate.  If prior to the first day
               ------------------------------------
of any Interest Period:

          (a)  the Administrative Agent shall have determined (which
     determination shall be conclusive and binding upon the Borrower) that, by
     reason of circumstances affecting the relevant market, adequate and
     reasonable means do not exist for ascertaining the Eurodollar Rate for such
     Interest Period, or

          (b)  the Administrative Agent shall have received notice from the
     Lenders holding 66-2/3% of the Loans to which such Interest Period is
     applicable that the Eurodollar Rate determined or to be determined for such
     Interest Period will not adequately and fairly reflect the cost to such
     Lenders (as conclusively certified by such Lenders) of making or
     maintaining their affected Loans during such Interest Period, then the
     Administrative Agent shall give telecopy or telephonic notice thereof to
     the Borrower and the affected Lenders as soon as practicable thereafter.
     If such notice is given (x) any Eurodollar Loans requested to be made on
     the first day of such Interest Period shall be made as ABR Loans, (y) any
     Loans that were to have been converted on the first day of such Interest
     Period to Eurodollar Loans shall be converted to or continued as ABR Loans
     and (z) any outstanding Eurodollar Loans shall be converted, on the first
     day of such Interest Period, to ABR Loans.  Until such notice has been
     withdrawn by the Administrative Agent, no further Eurodollar Loans under
     such Commitments shall be made or continued as such, nor shall the Borrower
     have the right to convert Loans to Eurodollar Loans.

          4.11 Pro Rata Treatment and Payments.  (a)  Each borrowing by the
               -------------------------------
     Borrower from the Lenders hereunder, each payment by the Borrower on
     account of any commitment fee hereunder and any reduction of the
     Commitments of the Lenders shall be made pro rata according to the
     respective relevant Commitment Percentages of the Lenders holding
     obligations in respect of which such amounts were paid.  Each payment
     (including each prepayment) by the Borrower on account of principal of and
     (subject to the provisions of subsection 4.12) interest on the Loans shall
     be made pro rata according to the respective outstanding principal amounts
     of such Loans then held by the Lenders.
<PAGE>

                                                                              23

     Except as otherwise set forth herein, all payments (including prepayments)
     to be made by the Borrower hereunder, whether on account of principal,
     interest, fees or otherwise, shall be made without set off or counterclaim
     and shall be made prior to 12:00 Noon, New York City time, on the due date
     thereof to the Administrative Agent, for the account of the applicable
     Lenders, at the Administrative Agent's office specified in subsection 11.3,
     in Dollars and in immediately available funds. The Administrative Agent
     shall distribute such payments to the Lenders holding obligations on
     account of which such amounts were paid promptly upon receipt in like funds
     as received. If any payment hereunder becomes due and payable on a day
     other than a Business Day, such payment shall be extended to the next
     succeeding Business Day, and, with respect to payments of principal,
     interest thereon shall be payable at the then applicable rate during such
     extension.

          (b)  Unless the Administrative Agent shall have been notified in
     writing by any Lender prior to a borrowing that such Lender will not make
     the amount that would constitute its relevant Commitment Percentage of such
     borrowing available to the Administrative Agent, the Administrative Agent
     may assume that such Lender is making such amount available to the
     Administrative Agent, and the Administrative Agent may, in reliance upon
     such assumption, make available to the Borrower a corresponding amount.  If
     such amount is not made available to the Administrative Agent by the
     required time on the Borrowing Date therefor, such Lender shall pay to the
     Administrative Agent, on demand, such amount with interest thereon at a
     rate equal to the daily average Federal Funds Effective Rate for the period
     until such Lender makes such amount immediately available to the
     Administrative Agent.  A certificate of the Administrative Agent submitted
     to any Lender with respect to any amounts owing under this subsection 4.11
     shall be conclusive in the absence of manifest or demonstrable error.  If
     such Lender's relevant Commitment Percentage of such borrowing is not made
     available to the Administrative Agent by such Lender within three Business
     Days of such Borrowing Date, the Administrative Agent shall also be
     entitled to recover such amount with interest thereon at the rate per annum
     applicable to ABR Loans hereunder, on demand, from the Borrower.

          (c)  Notwithstanding anything to the contrary contained herein, in the
     event that the Administrative Agent shall make any payment to a Lender on
     account of amounts owing to such Lender by the Borrower hereunder and the
     Administrative Agent either (i) shall not receive the corresponding amount
     from the Borrower or (ii) shall be required to return such amount to the
     Borrower, such Lender shall (upon the request of the Administrative Agent)
     promptly return to the Administrative Agent the amount of such payment.

          4.12 Illegality.  Notwithstanding any other provision herein, if the
               ----------
adoption of or any change in any Requirement of Law or in the interpretation or
application thereof shall make it unlawful for any Lender to make or maintain
Eurodollar Loans as contemplated by this Agreement, (a) the commitment of such
Lender hereunder to make Eurodollar Loans, continue Eurodollar Loans as such and
convert ABR Loans to Eurodollar Loans shall forthwith be cancelled and (b) such
Lender's Loans then outstanding as Eurodollar Loans, if any, shall be converted
automatically to ABR Loans on the respective last days of the then current
Interest Periods with respect to such Loans or within such earlier period as
required by law.  If any such
<PAGE>

                                                                              24

conversion of a Eurodollar Loan occurs on a day which is not the last day of the
then current Interest Period with respect thereto, the Borrower shall pay to
such Lender such amounts, if any, as may be required pursuant to subsection
4.15.

          4.13  Requirements of Law.  (a)  If the adoption of or any change in
                -------------------
any Requirement of Law or in the interpretation or application thereof or
compliance by any Lender with any request or directive (whether or not having
the force of law) from any central bank or other Governmental Authority made
subsequent to the date hereof:

          (i)   shall subject any Lender to any tax of any kind whatsoever with
     respect to this Agreement, any Note or any Eurodollar Loan made by it, or
     change the basis of taxation of payments to such Lender in respect thereof
     (except for Non-Excluded Taxes covered by subsection 4.14 and changes in
     the rate of tax on the overall net income of such Lender);

          (ii)  shall impose, modify or hold applicable any reserve, special
     deposit, compulsory loan or similar requirement against assets held by,
     deposits or other liabilities in or for the account of, advances, loans or
     other extensions of credit by, or any other acquisition of funds by, any
     office of such Lender which is not otherwise included in the determination
     of the Eurodollar Rate hereunder; or

          (iii) shall impose on such Lender any other condition; and the result
     of any of the foregoing is to increase the cost to such Lender, by an
     amount which such Lender deems to be material, of making, converting into,
     continuing or maintaining Eurodollar Loans or to reduce any amount
     receivable hereunder in respect thereof, then, in any such case, the
     Borrower shall promptly pay such Lender such additional amount or amounts
     as will compensate such Lender for such increased cost or reduced amount
     receivable.

          (b)   If any Lender shall have determined that the adoption of or any
     change in any Requirement of Law regarding capital adequacy or in the
     interpretation or application thereof or compliance by such Lender or any
     corporation controlling such Lender with any request or directive regarding
     capital adequacy (whether or not having the force of law) from any
     Governmental Authority made subsequent to the date hereof shall have the
     effect of reducing the rate of return on such Lender's or such
     corporation's capital as a consequence of its obligations hereunder to a
     level below that which such Lender or such corporation could have achieved
     but for such adoption, change or compliance (taking into consideration such
     Lender's or such corporation's policies with respect to capital adequacy)
     by an amount reasonably deemed by such Lender to be material, then from
     time to time, the Borrower shall promptly pay to such Lender such
     additional amount or amounts as will compensate such Lender for such
     reduction.

          (c)   If any Lender becomes entitled to claim any additional amounts
     pursuant to this subsection, it shall promptly notify the Borrower (with a
     copy to the Administrative Agent) of the event by reason of which it has
     become so entitled.  A certificate as to any additional amounts payable
     pursuant to this subsection submitted by such Lender to the Borrower (with
     a copy to the Administrative Agent) shall be conclusive in the absence of
     manifest or demonstrable error.  The agreements in this
<PAGE>

                                                                              25

     subsection shall survive the termination of this Agreement and the payment
     of the Loans and all other amounts payable hereunder.

          4.14 Taxes.  (a)  All payments made by the Borrower under this
               -----
Agreement and any Notes shall be made free and clear of, and without deduction
or withholding for or on account of, any present or future income, stamp or
other taxes, levies, imposts, duties, charges, fees, deductions or withholdings,
now or hereafter imposed, levied, collected, withheld or assessed by any
Governmental Authority, excluding net income taxes and franchise taxes (imposed
in lieu of net income taxes) imposed on the Administrative Agent or any Lender
as a result of a present or former connection between the Administrative Agent
or such Lender and the jurisdiction of the Governmental Authority imposing such
tax or any political subdivision or taxing authority thereof or therein (other
than any such connection arising solely from the Administrative Agent or such
Lender having executed, delivered or performed its obligations or received a
payment under, or enforced, this Agreement or any Note).  If any such non-
excluded taxes, levies, imposts, duties, charges, fees deductions or
withholdings ("Non-Excluded Taxes") are required to be withheld from any amounts
               ------------------
payable to the Administrative Agent or any Lender hereunder or under any Note,
the amounts so payable to the Administrative Agent or such Lender shall be
increased to the extent necessary to yield to the Administrative Agent or such
Lender (after payment of all Non-Excluded Taxes) interest or any such other
amounts payable hereunder at the rates or in the amounts specified in this
Agreement, provided, however, that the Borrower shall not be required to
           --------  -------
increase any such amounts payable to any Lender that is not organized under the
laws of the United States of America or a state thereof if such Lender fails to
comply with the requirements of paragraph (b) of this subsection.  Whenever any
Non-Excluded Taxes are payable by the Borrower, as promptly as possible
thereafter the Borrower shall send to the Administrative Agent for its own
account or for the account of such Lender, as the case may be, a certified copy
of an original official receipt received by the Borrower showing payment
thereof.  If the Borrower fails to pay any Non-Excluded Taxes when due to the
appropriate taxing authority or fails to remit to the Administrative Agent the
required receipts or other required documentary evidence, the Borrower shall
indemnify the Administrative Agent and the Lenders for any incremental taxes,
interest or penalties that may become payable by the Administrative Agent or any
Lender as a result of any such failure.  The agreements in this subsection shall
survive the termination of this Agreement and the payment of the Loans and all
other amounts payable hereunder.

               (b)    Each Lender that is not incorporated under the laws of the
     United States of America or a state thereof shall:

               (i)    deliver to the Borrower and the Administrative Agent (A)
     two duly completed copies of United States Internal Revenue Service Form
     1001 or 4224, or successor applicable form, as the case may be, and (B) an
     Internal Revenue Service Form W-8 or W-9, or successor applicable form, as
     the case may be;

               (ii)   deliver to the Borrower and the Administrative Agent two
     further copies of any such form or certification on or before the date that
     any such form or certification expires or becomes obsolete and after the
     occurrence of any event requiring a change in the most recent form
     previously delivered by it to the Borrower; and

               (iii)  obtain such extensions of time for filing and complete
     such forms or certifications as may reasonably be requested by the Borrower
     or the Administrative Agent; unless in any such case an event (including,
     without limitation, any change in
<PAGE>

                                                                              26

     treaty, law or regulation) has occurred prior to the date on which any such
     delivery would otherwise be required which renders all such forms
     inapplicable or which would prevent such Lender from duly completing and
     delivering any such form with respect to it and such Lender so advises the
     Borrower and the Administrative Agent. Such Lender shall certify (i) in the
     case of a Form 1001 or 4224, that it is entitled to receive payments under
     this Agreement without deduction or withholding of any United States
     federal income taxes and (ii) in the case of a Form W-8 or W-9, that it is
     entitled to an exemption from United States backup withholding tax. Each
     Person that shall become a Lender or a Participant pursuant to subsection
     11.7 shall, upon the effectiveness of the related transfer, be required to
     provide all of the forms and statements required pursuant to this
     subsection, provided that in the case of a Participant such Participant
     shall furnish all such required forms and statements to the Lender from
     which the related participation shall have been purchased.

          4.15  Indemnity.  The Borrower agrees to indemnify each Lender and to
                ---------
hold each Lender harmless from any loss or expense which such Lender may sustain
or incur as a consequence of (a) default by the Borrower in making a borrowing
of, conversion into or continuation of Eurodollar Loans after the Borrower has
given a notice requesting the same in accordance with the provisions of this
Agreement, (b) default by the Borrower in making any prepayment after the
Borrower has given a notice thereof in accordance with the provisions of this
Agreement or (c) the making of a prepayment of Eurodollar Loans on a day which
is not the last day of an Interest Period with respect thereto.  Such
indemnification may include an amount equal to the excess, if any, of (i) the
amount of interest which would have accrued on the amount so prepaid, or not so
borrowed, converted or continued, for the period from the date of such
prepayment or of such failure to borrow, convert or continue to the last day of
such Interest Period (or, in the case of a failure to borrow, convert or
continue, the Interest Period that would have commenced on the date of such
failure) in each case at the applicable rate of interest for such Loans provided
for herein (excluding, however, the Applicable Margin included therein, if any)
over (ii) the amount of interest (as reasonably determined by such Lender) which
would have accrued to such Lender on such amount by placing such amount on
deposit for a comparable period with leading banks in the interbank eurodollar
market.  This covenant shall survive the termination of this Agreement and the
payment of the Loans and all other amounts payable hereunder.

          4.16  Certain Fees.  The Borrower agrees to pay to the Administrative
                ------------
Agent, for its own account, a non-refundable administration's fee in an amount
previously agreed to with the Administrative Agent, payable in the manner and on
the dates so previously agreed.

          4.17  Change of Lending Office.  Each Lender agrees that if it makes
                ------------------------
any demand for payment under subsection 4.13 or 4.14(a), or if any adoption or
change of the type described in subsection 4.13 shall occur with respect to it,
it will use reasonable efforts (consistent with its internal policy and legal
and regulatory restrictions and so long as such efforts would not be
disadvantageous to it, as determined in its sole discretion) to designate a
different lending office if the making of such a designation would reduce or
obviate the need for the Borrower to make payments under subsection 4.13 or
4.14(a), or would eliminate or reduce the effect of any adoption or change
described in subsection 4.12.
<PAGE>

                                                                              27

                   SECTION 5  REPRESENTATIONS AND WARRANTIES

          To induce the Administrative Agent and the Lenders to enter into this
Agreement and to make the Loans, the Borrower hereby represents and warrants to
the Administrative Agent and each Lender (on the date of each borrowing
hereunder and on the Reorganization Date, with LegacyCo being deemed to be the
"Borrower" on the Reorganization Date) that:

          5.1  Financial Condition.  (a)  The audited consolidated balance
               -------------------
sheets of Premisys as at June 25, 1999 and June 26, 1998, and the related
consolidated statements of income and of cash flows for the fiscal years ended
on such dates, reported on by and accompanied by an unqualified report from
PricewaterhouseCoopers LLP, present fairly the consolidated financial condition
of Premisys as at such date, and the consolidated results of its operations and
its consolidated cash flows for the respective fiscal years then ended.  The
unaudited consolidated balance sheet of Premisys as at September 24, 1999, and
the related unaudited consolidated statements of income and cash flows for the
three-month period ended on such date, present fairly the consolidated financial
condition of Premisys as at such date, and the consolidated results of its
operations and its consolidated cash flows for the three- month period then
ended (subject to normal year-end audit adjustments).  All such financial
statements, including the related schedules and notes thereto, have been
prepared in accordance with GAAP applied consistently throughout the periods
involved (except as approved by the aforementioned firm of accountants and
disclosed therein).  The Borrower and its Subsidiaries do not have any material
Guarantee Obligations, contingent liabilities and liabilities for taxes, or any
long-term leases or unusual forward or long-term commitments, including any
interest rate or foreign currency swap or exchange transaction or other
obligation in respect of derivatives, that are not reflected in the most recent
financial statements referred to in this paragraph.  During the period from June
25, 1999 to and including the Closing Date, there has been no sale, transfer or
other disposition by Premisys of any material part of its business or property,
other than the sales, transfers and other dispositions constituting the
Transaction.

          (b)  The unaudited pro forma consolidated balance sheet of Premisys as
     at each of June 25, 1999 and September 24, 1999, and the related unaudited
     consolidated statements of income and cash flows for the fiscal year or
     fiscal quarter (as the case may be) ended on each such date, present fairly
     the consolidated financial condition of Premisys as at such date, and the
     consolidated results of its operations and its consolidated cash flows for
     the fiscal period then ended (subject to normal year-end audit adjustments,
     in the case of the financial statements as at September 24, 1999).  All
     such financial statements, including the related schedules and notes
     thereto, have been prepared in accordance with GAAP applied consistently
     throughout the periods involved and have been adjusted to reflect, on a pro
     forma basis, the financial performance and position only of the businesses
     which will comprise LegacyCo on the Reorganization Date.

          (c)  The unaudited pro forma consolidated balance sheet (including the
     notes thereto) as at September 24, 1999 of:

               (i)  AcquisitionCo and its consolidated Subsidiaries, copies of
          which have heretofore been furnished to each Lender, has been prepared
          giving effect
<PAGE>

                                                                              28

          (as if such events had occurred on such date) to the consummation of
          the Tender Offer, the Merger and the Loans to be made hereunder on the
          Closing Date; and

               (ii)  LegacyCo and its consolidated Subsidiaries, copies of which
          have heretofore been furnished to each Lender, have been prepared
          giving effect (as if such events had occurred on such date) to the
          consummation of the Transaction and the Loans to be made hereunder.

Each such pro forma consolidated balance sheet has been prepared based on the
best information reasonably available to the Borrower as of the date of delivery
thereof, and presents fairly on a pro forma basis the estimated financial
position of Borrower and its consolidated Subsidiaries as at September 24, 1999,
assuming that the events specified in the preceding sentence had actually
occurred at such date.

          (d)  The unaudited pro forma consolidated summary cash flow statement
     for the period of four consecutive fiscal quarters ended September 24, 1999
     of LegacyCo and its consolidated Subsidiaries, copies of which have
     heretofore been furnished to each Lender, have been prepared giving effect
     (as if such events had occurred on such date) to the consummation of the
     Transaction and the Loans to be made hereunder.  Such unaudited pro forma
     consolidated summary balance sheet has been prepared based on the best
     information reasonably available to the Borrower as of the date of delivery
     thereof, and presents fairly on a pro forma basis the estimated cash flow
     results of LegacyCo and its consolidated Subsidiaries for the period ended
     September 24, 1999, assuming that the events specified in the preceding
     sentence had actually occurred at the first day of such period.  Such
     unaudited pro forma consolidated summary cash flow statement demonstrates
     that LegacyCo would have had positive cash flow (after, among other things,
     the payment of debt service) if the Transaction had occurred on the first
     day of the period of four consecutive fiscal quarters ended September 24,
     1999.

          5.2  No Change.  Since June 25, 1999, there has been no development or
               ---------
event which has had or could reasonably be expected to have a Material Adverse
Effect (it being understood that the consummation of the Asset Transfer does
not, in itself, constitute such a development or event).

          5.3  Corporate Existence; Compliance with Law.  Each of the Borrower
               ----------------------------------------
and its Subsidiaries (a) is duly organized, validly existing and in good
standing under the laws of the jurisdiction of its organization, (b) has the
corporate power and authority, and the legal right, to own and operate its
property, to lease the property it operates as lessee and to conduct the
business in which it is currently engaged, (c) is duly qualified as a foreign
corporation and in good standing under the laws of each jurisdiction where its
ownership, lease or operation of property or the conduct of its business
requires such qualification except where the failure to so qualify could not, in
the aggregate, reasonably be expected to have a Material Adverse Effect and (d)
is in compliance with all Requirements of Law except to the extent that the
failure to comply therewith could not, in the aggregate, reasonably be expected
to have a Material Adverse Effect.

          5.4  Corporate Power; Authorization; Enforceable Obligations.  Each
               -------------------------------------------------------
Credit Party has the corporate (or analogous) power and authority, and the legal
right, to make, deliver
<PAGE>

                                                                              29

and perform the Credit Documents to which it is a party and has taken all
necessary corporate (or analogous) action to authorize the execution, delivery
and performance of the Credit Documents to which it is a party. The Borrower has
the corporate (or analogous) power and authority, and the legal right, to borrow
hereunder and has taken all necessary corporate action to authorize the
borrowings on the terms and conditions of this Agreement. To the best of the
Borrower's knowledge, after reasonable inquiry, no consent or authorization of,
filing with, notice to or other act by or in respect of, any Governmental
Authority or any other Person is required in connection with the borrowings
hereunder or with the execution, delivery, performance, validity or
enforceability of the Credit Documents to which any Credit Party is a party.
This Agreement has been, and each other Credit Document to which it is a party
will be, duly executed and delivered on behalf of each Credit Party. This
Agreement constitutes, and each other Credit Document to which it is a party
when executed and delivered will constitute, a legal, valid and binding
obligation of each Credit Party, enforceable against the Borrower or the
relevant Subsidiary, as the case may be, in accordance with its terms, subject
to the effects of bankruptcy, insolvency, fraudulent conveyance, reorganization,
moratorium and other similar laws relating to or affecting creditors' rights
generally, general equitable principles (whether considered in a proceeding in
equity or at law) and an implied covenant of good faith and fair dealing.

          5.5  No Legal Bar.  The execution, delivery and performance of each
               ------------
Credit Document, the incurrence or issuance of and use of the proceeds of the
Loans and the transactions contemplated by the Credit Documents (a) will not
violate any Requirement of Law or any Contractual Obligation applicable to or
binding upon the Borrower or any of its Subsidiaries or any of their respective
properties or assets, in any manner which could reasonably be expected to result
in a Material Adverse Effect and (b) will not result in the creation or
imposition of any Lien on any of its properties or assets pursuant to any
Requirement of Law applicable to it, as the case may be, or any of its
Contractual Obligations, except for the Liens arising under the Security
Documents.

          5.6  No Material Litigation.  No litigation by, investigation by, or
               ----------------------
proceeding of or before any arbitrator or any Governmental Authority is pending
or, to the knowledge of the Borrower, threatened by or against the Borrower or
any of its Subsidiaries or against any of its or their respective properties or
revenues (including after giving effect to the Tender Offer and Merger) (a) with
respect to any Credit Document, the Loans made hereunder, the use of proceeds
thereof and the other transactions contemplated hereby, (b) with respect to any
Acquisition Document or any transactions contemplated thereby which affect any
material provisions or any material transaction contemplated thereby or (c)
which could reasonably be expected to have a Material Adverse Effect.

          5.7  No Default.  Neither the Borrower nor any of its Subsidiaries is
               ----------
in default under or with respect to any of its Contractual Obligations in any
respect which could reasonably be expected to have a Material Adverse Effect.
No Default or Event of Default has occurred and is continuing.

          5.8  Ownership of Property; Liens.  The Borrower and each of its
               ----------------------------
Subsidiaries has good record and marketable title in fee simple to, or a valid
leasehold interest in, all its real property, and good title to, or a valid
leasehold interest in, all its other property, and none of such property is
subject to any Lien except as permitted by subsection 8.3.
<PAGE>

                                                                              30

          5.9  Intellectual Property. The Borrower and each of its Subsidiaries
               ---------------------
owns, or is licensed to use, all trademarks, tradenames, copyrights, technology,
know-how and processes material to the conduct of its business as currently
conducted (the "Intellectual Property"). Except as set forth in Schedule 5.9, no
                ---------------------
claim has been asserted and is pending by any Person challenging or questioning
the use of any such Intellectual Property or the validity or effectiveness of
any such Intellectual Property, nor does the Borrower know of any valid basis
for any such claim. Except as set forth in Schedule 5.9, the use of such
Intellectual Property by the Borrower and its Subsidiaries does not infringe on
the rights of any Person, except for such claims and infringements that, in the
aggregate, could not reasonably be expected to have a Material Adverse Effect.

          5.10 No Burdensome Restrictions. No Requirement of Law or
               --------------------------
Contractual Obligation of the Borrower or any of its Subsidiaries could
reasonably be expected to have a Material Adverse Effect.

          5.11 Taxes. Each of the Borrower and its Subsidiaries has filed or
               -----
caused to be filed all tax returns (or has requested and has received extensions
from the appropriate Governmental Authority) which, to the knowledge of the
Borrower, are required to be filed and has paid all taxes shown to be due and
payable on said returns or on any assessments made against it or any of its
property and all other taxes, fees or other charges imposed on it or any of its
property by any Governmental Authority (other than any the amount or validity of
which are currently being contested in good faith by appropriate proceedings and
with respect to which reserves in conformity with GAAP have been provided on the
books of the Borrower or its Subsidiaries, as the case may be); no tax Lien has
been filed, and, to the knowledge of the Borrower, no claim is being asserted,
with respect to any such tax, fee or other charge.

          5.12 Federal Regulations. No part of the proceeds of any Loans will
               -------------------
be used for any purpose which violates, or would be inconsistent with, the
provisions of Regulation T, U or X of the Board of Governors of the Federal
Reserve System as now and from time to time hereafter in effect.

          5.13 ERISA. Neither a Reportable Event nor an "accumulated funding
               -----
deficiency" (within the meaning of Section 412 of the Code or Section 302 of
ERISA) has occurred during the five-year period prior to the date on which this
representation is made or deemed made with respect to any Plan, and each Plan
has complied in all material respects with the applicable provisions of ERISA
and the Code. No termination of a Single Employer Plan has occurred, and no Lien
in favor of the PBGC or a Plan has arisen, during such five-year period. The
present value of all accrued benefits under each Single Employer Plan (based on
those assumptions used to fund such Plans) did not, as of the last annual
valuation date prior to the date on which this representation is made or deemed
made, exceed the value of the assets of such Plan allocable to such accrued
benefits. Neither the Borrower nor any Commonly Controlled Entity has had a
complete or partial withdrawal from any Multiemployer Plan, and neither the
Borrower nor any Commonly Controlled Entity would become subject to any
liability under ERISA if the Borrower or any such Commonly Controlled Entity
were to withdraw completely from all Multiemployer Plans as of the valuation
date most closely preceding the date on which this representation is made or
deemed made. No such Multiemployer Plan is in Reorganization or Insolvent.
<PAGE>

                                                                              31

          5.14  Investment and Holding Company Status. Neither the Borrower nor
                -------------------------------------
any of its Subsidiaries is (a) an "investment company" as defined in, or subject
to regulation under, the Investment Company Act of 1940 or (b) a "holding
company" as defined in, or subject to regulation under, the Public Utility
Holding Company Act of 1935.

          5.15  Environmental Matters.  Except to the extent that the facts and
                ---------------------
circumstances giving rise to all such failures to be so true and correct are
not, in the aggregate, reasonably likely to result in the payment of a Material
Environmental Amount:

          (a)   The facilities and properties owned, leased or operated by the
     Borrower or any of its Subsidiaries (the "Properties") do not contain, and
                                               ----------
     have not previously contained, any Materials of Environmental Concern in
     amounts or concentrations which (i) constitute or constituted a violation
     of, or (ii) could reasonably be expected to give rise to liability under,
     any Environmental Law.

          (b)   The Properties and all operations at the Properties are in
     compliance, and have in the last five years been in compliance, in all
     material respects with all applicable Environmental Laws, and there is no
     contamination at, under or about the Properties or violation of any
     Environmental Law with respect to the Properties or the business operated
     by the Borrower or any of its Subsidiaries (the "Business") which could
                                                      --------
     materially interfere with the continued operation of the Properties or
     materially impair the fair saleable value thereof.

          (c)   Neither the Borrower nor any of its Subsidiaries has received
     any notice of violation, alleged violation, non-compliance, liability or
     potential liability regarding environmental matters or compliance with
     Environmental Laws with regard to any of the Properties or the Business,
     nor does the Borrower have knowledge or reason to believe that any such
     notice will be received or is being threatened.

          (d)   Materials of Environmental Concern have not been transported or
     disposed of from the Properties in violation of, or in a manner or to a
     location which could reasonably be expected to give rise to liability
     under, any Environmental Law, nor have any Materials of Environmental
     Concern been generated, treated, stored or disposed of at, on or under any
     of the Properties in violation of, or in a manner that could reasonably be
     expected to give rise to liability under, any applicable Environmental Law.

          (e)   No judicial proceeding or governmental or administrative action
     is pending or, to the knowledge of the Borrower, threatened, under any
     Environmental Law to which the Borrower or any Subsidiary is or will be
     named as a party with respect to the Properties or the Business, nor are
     there any consent decrees or other decrees, consent orders, administrative
     orders or other orders, or other administrative or judicial requirements
     outstanding under any Environmental Law with respect to the Properties or
     the Business.

          (f)   There has been no release or threat of release of Materials of
     Environmental Concern at or from the Properties, or arising from or related
     to the operations of the Borrower or any Subsidiary in connection with the
     Properties or otherwise in connection with the Business, in violation of or
     in amounts or in a manner
<PAGE>

                                                                              32

     that could reasonably give rise to liability under Environmental Laws.

     (a)Each of the representations and warranties set forth in subsections
     5.16(a) through (f) is true and correct with respect to each parcel of real
     property owned or operated by the Borrower or any of its Subsidiaries
     (other than the Properties).

          5.16  Security Documents. (a)  Upon execution and delivery thereof by
                ------------------
the parties thereto, each Security Document will be effective to create in favor
of the Administrative Agent, for the ratable benefit of the Lenders, a legal,
valid and enforceable security interest in the Collateral described therein and,
when the actions specified each Security Document have been duly taken, the
security interests granted pursuant thereto shall constitute a perfected first
lien on, and security interest in, all right, title and interest of the pledgor
party thereto in the Collateral described therein.

          (b)   Upon execution and delivery thereof by the parties thereto, each
     Foreign Pledge Agreement will be effective to create in favor of the
     Administrative Agent, for the ratable benefit of the Lenders, a legal,
     valid and enforceable security interest in not less than 65% of the Capital
     Stock of each Foreign Subsidiary which is directly owned by a Domestic
     Subsidiary and, when the actions (if any) specified in the legal opinion
     delivered in connection with such Foreign Pledge Agreement have been duly
     taken, the security interests granted pursuant thereto shall constitute a
     perfected first lien on, and security interest in, all right, title and
     interest of the pledgor party thereto in such Capital Stock.

          5.17  Acquisition Documents. The Administrative Agent and each Lender
                ---------------------
has received complete and correct copies of each of the Acquisition Documents
(including, without limitation, all exhibits, schedules and disclosure letters
referred to therein or delivered pursuant thereto) and all amendments thereto,
waivers relating thereto and other side letters or agreements affecting the
terms thereof. None of the Acquisition Documents will have been amended,
supplemented or otherwise modified (including waivers) since the date hereof,
except (a) amendments, supplements and other modifications (including waivers)
to the Acquisition Documents which (i) do not increase the price paid for the
Shares, (ii) do not affect the material conditions to AcquisitionCo's obligation
to purchase the Shares (other than any waiver of the requirement that the
Tendered Shares constitute at least 75% of the issued and outstanding Shares)
and (iii) would not adversely affect the rights or interests of the
Administrative Agent and the Lenders or (b) as approved by the Administrative
Agent. Each Acquisition Document to which the Borrower or any of its
Subsidiaries is a party has been duly executed and delivered by the Borrower or
such Subsidiary, as the case may be, and to the best knowledge of the Borrower
and each of its Subsidiaries, each Acquisition Document has been duly executed
and delivered by the parties thereto other than the Borrower and its
Subsidiaries, is in full force and effect and is enforceable against the parties
thereto. The representations and warranties of the Borrower and each of its
Subsidiaries contained in each Acquisition Document to which the Borrower or
such Subsidiary, as the case may be, is a party were true and correct in all
material respects on each date when made. To the knowledge of the Borrower and
each of its Subsidiaries, the representations and warranties of each other party
to each Acquisition Document contained therein were true and correct in all
material respects on each date when made.

          5.18  Capital Call Obligations. To the best knowledge of the Borrower,
                ------------------------
(a) the Capital Call Agreement to which each Investor is a party remains in full
force and effect and is
<PAGE>

                                                                              33

enforceable against such Investor, (b) the Assignment of Capital Call Rights
remains in full force and effect and is enforceable against Zhone and (c) after
giving effect to the provisions of the Security Documents, the Administrative
Agent has the right and ability to make capital calls upon the Investors with
respect to the Assigned Interests without the consent of any Person at any time
when an Event of Default is continuing; provided that the representations and
warranties contained in this subsection 5.18 shall be made (or deemed made) by
the Borrower only prior to the Collateral Substitution Date.

          5.19  Accuracy and Completeness of Information.  No information,
                ----------------------------------------
financial statement, report, certificate or other document prepared or furnished
by or on behalf of any Credit Party to the Administrative Agent or any Lender in
connection with this Agreement (including, without limitation, the materials
furnished to the Lenders in connection with the syndication of the Commitments
hereunder), any other Credit Document, or any of the Acquisition Documents (but
excluding all projections and pro forma financial statements, which shall have
been prepared in good faith and based upon reasonable assumptions) contains any
untrue statement of a fact or omits to state any fact necessary to make the
statements herein or therein not misleading in any material respect.

          5.20  Solvency.  Each Credit Party is, and after giving effect to the
                --------
Transaction and the incurrence of all Indebtedness and obligations being
incurred in connection herewith and therewith will be and will continue to be,
Solvent. For purposes of this subsection 5.20, the term "Solvent," when used
with respect to any Person, means that, as of any date of determination, (a) the
amount of the "present fair saleable value" of the assets of such Person will,
as of such date, exceed the amount of all "liabilities of such Person,
contingent or otherwise", as of such date, as such quoted terms are determined
in accordance with applicable federal and state laws governing determinations of
the insolvency of debtors, (b) the present fair saleable value of the assets of
such Person will, as of such date, be greater than the amount that will be
required to pay the liability of such Person on its debts as such debts become
absolute and matured, (c) such Person will not have, as of such date, an
unreasonably small amount of capital with which to conduct its business, and (d)
such Person will be able to pay its debts as they mature. For purposes of this
definition, (i) "debt" means liability on a "claim", and (ii) "claim" means any
(x) right to payment, whether or not such a right is reduced to judgment,
liquidated, unliquidated, fixed, contingent, matured, unmatured, disputed,
undisputed, legal, equitable, secured or unsecured or (y) right to an equitable
remedy for breach of performance if such breach gives rise to a right to
payment, whether or not such right to an equitable remedy is reduced to
judgment, fixed, contingent, matured or unmatured, disputed, undisputed, secured
or unsecured.

                       SECTION 6.  CONDITIONS PRECEDENT

          6.1  Conditions to Initial Loans.  The agreement of each Lender to
               ---------------------------
make the initial Loans requested to be made by it is subject to the
satisfaction, immediately prior to or concurrently with the making of such Loan
(and, in any event, on or prior to December 31, 1999), of the following
conditions precedent:

          (a)  Credit Documents.  The Administrative Agent shall have
               ----------------
     received (i) this Agreement, executed and delivered by a duly authorized
     officer of the Borrower, (ii) each of the Security Documents contemplated
     by the definition of such term to be in
<PAGE>

                                                                              34

effect on the Closing Date and (iii) the Premisys Escrow Agreement, each
executed and delivered by a duly authorized officer of the parties thereto.

               (b)  Related Agreements. The Administrative Agent shall have
                    ------------------
received, with a copy for each Lender, true and correct copies, certified as to
authenticity by the Borrower, of (i) each of the Acquisition Documents and (ii)
such other documents or instruments as may be reasonably requested by the
Administrative Agent.

               (c)  Corporate Matters regarding Credit Parties. The
                    ------------------------------------------
Administrative Agent shall have received, with a counterpart for each Lender,
(i) a true and complete copy of the certificate of incorporation (or analogous
document) of each Credit Party, (ii) a true and complete copy of the By-laws (or
analogous document) of each Credit Party and (iii) a true and complete copy of
the resolutions of the Board of Directors (or analogous document) of each Credit
Party authorizing (A) the execution, delivery and performance by such Credit
Party of the Credit Documents to which it is a party, (B) in the case of the
Borrower, the borrowings contemplated hereunder, (C) the granting by such Credit
Party of any Liens purported to be created by it pursuant to the Security
Documents and (D) in the case of Premisys, the execution, delivery and
performance of its obligations under the Premisys Escrow Agreement. Such
documents shall be certified by the Secretary or an Assistant Secretary of such
Credit Party (or, if such credit party is not a corporation, a duly authorized
general partner or member thereof) as of the Closing Date, which certificate
shall (w) be in form and substance reasonably satisfactory to the Administrative
Agent, (x) certify that such documents are true and correct copies of the
originals thereof, (y) certify as to the incumbency and signature of the
officers of such Credit Party executing any Credit Document and (z) state that
the resolutions (or analogous authorizations) described in clause (iii) above
have not been amended, modified, revoked or rescinded.

               (d)  Consents, Licenses and Approvals. The Administrative Agent
                    --------------------------------
shall have received, with a counterpart for each Lender, a certificate of a
Responsible Officer of the Borrower stating that all consents, authorizations
and filings, if any, referred to in subsection 5.4 are in full force and effect.

               (e)  Legal Opinions. The Administrative Agent shall have
                    --------------
received, with a counterpart for each Lender, (i) from Latham & Watkins and/or
other acceptable counsel to Zhone, the Borrower and the other Credit Parties an
executed legal opinion which is in form and substance reasonably satisfactory to
the Administrative Agent and (ii) copies of all opinions delivered on or prior
to the Closing Date in connection with the Tender Offer, the Merger and the
Asset Transfer, with satisfactory reliance letters in favor of the
Administrative Agent and the Lenders; each such legal opinion shall be in form
and substance reasonably acceptable to the Administrative Agent and shall cover
such other matters incident to the transactions contemplated by this Agreement
as the Administrative Agent may reasonably require.

               (f)  Pledged Stock. The Administrative Agent shall have received
                    -------------
the certificates representing the shares of Capital Stock of AcquisitionCo which
are to be pledged pursuant to the Initial Collateral Agreement, together with an
undated stock
<PAGE>

                                                                              35

power for each such certificate executed in blank by a duly authorized officer
of the pledgor thereof.

               (g)  Actions to Perfect Liens. The Administrative Agent shall
                    ------------------------
have received evidence in form and substance satisfactory to it that all
filings, recordings, registrations and other actions, including, without
limitation, the filing of duly executed financing statements on form UCC-1,
necessary or, in the opinion of the Administrative Agent, desirable to perfect
the Liens created by the Security Documents (including, without limitation, the
Lien on the Tendered Shares of Premisys which are to be acquired by
AcquisitionCo on the Closing Date, but other than any Lien on the Assigned
Interests) shall have been completed.

               (h)  Lien Searches. The Administrative Agent shall have received
                    -------------
the results of a recent search by a Person reasonably satisfactory to the
Administrative Agent, of the Uniform Commercial Code, judgement and tax lien
filings which may have been filed with respect to personal property of Zhone,
AcquisitionCo, LegacyCo, Premisys and their respective subsidiaries, and the
results of such search shall be reasonably satisfactory to the Administrative
Agent.

               (i)  Escrow. Premisys shall have placed in escrow pursuant to the
                    ------
Premisys Escrow Agreement an amount of cash and securities (which securities
shall be reasonably satisfactory to the Administrative Agent) having an
aggregate fair market value equal to not less than the amount of the Aggregate
Acquisition Loan Commitment then in effect.

               (j)  Receipt of Capital. The Administrative Agent shall have
                    ------------------
received a certificate of a Responsible Officer, dated the Closing Date, stating
that (i) Zhone has received irrevocable and unconditional capital commitments
with respect to at least $400,000,000 in equity from the Investors upon terms
reasonably satisfactory to the Administrative Agent, (ii) Zhone shall have
received at least $140,000,000 in cash equity through drawings under the capital
commitments described in clause (i) above and shall have contributed or loaned
(in accordance with the terms hereof) such amounts to the Borrower and (iii) the
Borrower shall have utilized the $140,000,000 in capital contributions and loans
received by it pursuant to clause (ii) above to purchase Shares.

              (k)  Tender Offer. (i) The Merger Agreement and all related
                   ------------
documentation shall have been duly executed and delivered by the parties thereto
in form and substance reasonably satisfactory to the Administrative Agent and
the Lenders, (ii) the material conditions to the Tender Offer specified in the
Tender Offer Documents (as in effect on the date hereof) shall have been and
shall continue to be satisfied in all material respects, (iii) the Acquisition
Documents shall not have been amended, supplemented, waived or otherwise
modified in any material respect, except as contemplated by subsection 8.16,
(iv) the obligations of the parties thereto to be performed at or prior to the
acceptance and purchase of the Tendered Shares (other than the payment of the
purchase price for the Tendered Shares) shall have been performed or complied
with by AcquisitionCo and Premisys, except where the failure so to comply or
perform could not reasonably be expected to have a Material Adverse Effect, (v)
the Board of Directors of Premisys shall have approved and/or recommended the
Acquisition
<PAGE>

                                                                              36

to the shareholders of Premisys, (vi) the portion of the Shares beneficially
owned by AcquisitionCo, together with the portion of the Shares accepted for
payment pursuant to the Tender Offer, is not less than the amount necessary to
permit the Merger to be consummated without the affirmative vote of any
shareholders other than the Borrower and its Subsidiaries and there shall not
have been a material change in the number of Shares since June 25, 1999 and
(vii) AcquisitionCo shall have accepted all Tendered Shares for purchase, shall
have deposited the funds necessary for the purchase of such Tendered Shares with
the depositary and instructed the depositary to promptly pay for such Tendered
Shares.

               (l)  Purchase Price. The aggregate consideration to be paid for
                    --------------
purchase of the Shares pursuant to the Tender Offer and the Merger shall be not
more than $255,000,000 and the aggregate amount of fees and expenses to be
incurred in connection with the Transaction shall not exceed $10,000,000.

               (m)  No Consents. Each of Zhone, AcquisitionCo, LegacyCo,
               ----------------
Premisys and their respective Subsidiaries shall have obtained all consents and
approvals of Governmental Authorities and third parties necessary or reasonably
advisable in connection with the Transaction, the Loans hereunder and the
continuing operations of the Borrower and its Subsidiaries (after giving effect
to the Transaction); all such consents and approvals shall be in full force and
effect and all applicable appeal and waiting periods shall have expired without
any governmental or judicial action being taken or threatened that has had or
would be reasonably likely to have the effect of restraining, preventing or
imposing burdensome conditions on the Transaction and the other transactions
contemplated hereby.

               (n)  Corporate Structure. The Administrative Agent and the
                    -------------------
Lenders shall have received a written description of the material assets and
liabilities to be transferred to LegacyCo and its Subsidiaries pursuant to the
Asset Transfer, and such assets and liabilities shall be reasonably satisfactory
to the Administrative Agent.

               (o)  Fees. The Administrative Agent shall have received all fees
                    ----
and other amounts due and payable on or prior to the Closing Date, including, to
the extent invoiced a reasonable time prior to the Closing Date, reimbursement
or payment of all out-of-pocket expenses required to be reimbursed or paid by
the Borrower and its Subsidiaries hereunder or under any other Credit Document.

               (p)  Business Plan. The Borrower shall have delivered a business
                    -------------
plan for LegacyCo and its Subsidiaries for the period from the Closing Date
through the Maturity Date, which business plan shall be consistent in all
material respects with the projections and other information provided to the
Administrative Agent prior to the Closing Date.

               6.2  Conditions to Term Loan. In addition to the satisfaction or
                    -----------------------
waiver of the conditions specified in subsection 6.1, the agreement of each Term
Loan Lender to make its Term Loan is subject to the satisfaction of the
following conditions precedent:
<PAGE>

                                                                              37

               (a)  Related Agreements. The Administrative Agent shall have
                    ------------------
received, with a copy for each Lender, true and correct copies, certified as to
authenticity by the Borrower, of each of (i) each Stock Purchase Agreement, (ii)
each Capital Call Agreement, (iii) the Assignment of Capital Call Rights and
(iv) such other documents or instruments as may be reasonably requested by the
Administrative Agent.

               (b)  Capital Call Payments. The Administrative Agent shall have
                    ---------------------
received a true and correct copy of written instructions from Zhone to each
Investor specifying that, until such time as such Investor receives the
instructions contemplated by subsection 8.17(g) hereof, all payments made by
such Investor to Zhone on account of the Assigned Interests shall be paid
directly into the Cash Collateral Account (as defined in the AcquisitionCo Cash
Collateral Agreement); such instructions shall be irrevocable and unconditional,
and shall be in form and substance reasonably satisfactory to the Administrative
Agent.

              (c)  Actions to Perfect Liens. The Administrative Agent shall have
              -----------------------------
received evidence in form and substance satisfactory to it that all filings,
recordings, registrations and other actions, including, without limitation, the
filing of duly executed financing statements on form UCC-1, necessary or, in the
opinion of the Administrative Agent, desirable to perfect the Liens created by
the Security Documents on the Assigned Interests shall have been completed.

          6.3  Conditions to Each Loan. The agreement of each Lender to make
               -----------------------
any Loan requested to be made by it on any date (including, without limitation,
any Loan to be made on the Closing Date) is subject to the satisfaction of the
following conditions precedent:

              (a)  Representations and Warranties. Each of the representations
              -----------------------------------
and warranties made by the Borrower and the other Credit Parties in or pursuant
to the Credit Documents shall be true and correct in all material respects on
and as of such date as if made on and as of such date.

              (b)  No Default. No Default or Event of Default shall have
              ---------------
occurred and be continuing on such date or after giving effect to the Loans and
other extensions of credit requested to be made on such date.

              (c)  Margin Regulations.  The Borrower shall have furnished to the
              -----------------------
Administrative Agent and each Lender a duly completed and executed counterpart
of FR Form U-1 referred to in Regulation U.

                       SECTION 7. AFFIRMATIVE COVENANTS

          The Borrower hereby agrees that, so long as any Commitments remain in
effect or any amount is owing to any Lender or the Administrative Agent
hereunder or under any other Credit Document, the Borrower shall and (except in
the case of delivery of financial information, reports and notices) shall cause
each of its Subsidiaries to:

          7.1  Financial Statements.  Furnish to each Lender:
               --------------------
<PAGE>

                                                                              38

          (a)  as soon as available, but in any event within 90 days after the
end of each fiscal year of the Borrower, a copy of the consolidated balance
sheet of the Borrower and its consolidated Subsidiaries as at the end of such
year and the related consolidated statements of income and retained earnings and
of cash flows for such year, setting forth in each case in comparative form the
figures for the previous year, reported on without a "going concern" or like
qualification or exception, or qualification arising out of the scope of the
audit, by independent certified public accountants of nationally recognized
standing; and

          (b)  as soon as available, but in any event not later than 45 days
after the end of each of the first three quarterly periods of each fiscal year
of the Borrower, the unaudited consolidated balance sheet of the Borrower and
its consolidated Subsidiaries as at the end of such quarter and the related
unaudited consolidated statements of income and retained earnings and of cash
flows of the Borrower and its consolidated Subsidiaries for such quarter and the
portion of the fiscal year through the end of such quarter, setting forth in
each case in comparative form the figures for the previous year, certified by a
Responsible Officer as being fairly stated in all material respects (subject to
normal year-end audit adjustments); all such financial statements shall be
complete and correct in all material respects and shall be prepared in
reasonable detail and in accordance with GAAP applied consistently throughout
the periods reflected therein and with prior periods (except as approved by such
accountants or officer, as the case may be, and disclosed therein).

          7.2  Certificates; Other Information.  Furnish to each Lender:
               -------------------------------

          (a)  concurrently with the delivery of the financial statements
referred to in subsection 7.1(a), a certificate of the independent certified
public accountants reporting on such financial statements stating that in making
the examination necessary therefor no knowledge was obtained of any Default or
Event of Default, except as specified in such certificate;

          (b)  concurrently with the delivery of the financial statements
     referred to in subsections 7.1(a) and (b), a certificate of a Responsible
     Officer certifying:

               (i)   that, during such period, no Subsidiary has been formed or
          acquired (or, if any such Subsidiary has been formed or acquired, the
          Borrower has complied with the requirements of subsection 7.10 with
          respect thereto);

               (ii)  that, during such period, neither the Borrower nor any of
          its Subsidiaries has changed its name, its principal place of
          business, its chief executive office or the location of any material
          item of tangible Collateral without complying with the requirements of
          this Agreement and the Security Documents with respect thereto;

               (iii) that, during such period, each of the Borrower and its
          Subsidiaries has observed or performed all of its covenants and other
          agreements, and satisfied every condition, contained in this Agreement
          and the other Credit Documents to
<PAGE>

                                                                              39

          be observed, performed or satisfied by it (and including therein a
          reasonably detailed calculation of the covenants contained in
          subsection 8.1 hereof as of the last day of such period); and

               (iv)  prior to the Collateral Substitution Date, the amount
          remaining undrawn and available from each Investor as of the last day
          of such period on account of the Assigned Interests and the expiration
          date of each Capital Call Agreement;

     and that such Officer has obtained no knowledge of any Default or Event of
     Default except as specified in such certificate;

          (c)  not later than thirty days prior to the end of each fiscal year
     of the Borrower, a copy of the projections by the Borrower of the operating
     budget and cash flow budget of the Borrower and its Subsidiaries for the
     succeeding fiscal year, such projections to be accompanied by a certificate
     of a Responsible Officer to the effect that such projections have been
     prepared on the basis of sound financial planning practice and that such
     Officer has no reason to believe they are incorrect or misleading in any
     material respect;

          (d)  within five days after the same are sent, copies of all financial
     statements and reports which the Borrower sends to its stockholders
     generally, and within five days after the same are filed, copies of all
     financial statements and reports which the Borrower may make to, or file
     with, the Securities and Exchange Commission or any successor or analogous
     Governmental Authority; and

          (e)  promptly, such additional financial and other information as any
     Lender may from time to time reasonably request.

          7.3  Payment of Obligations.  Pay, discharge or otherwise satisfy at
               ----------------------
or before maturity or before they become delinquent, as the case may be, all its
obligations of whatever nature, except where the amount or validity thereof is
currently being contested in good faith by appropriate proceedings and reserves
in conformity with GAAP with respect thereto have been provided on the books of
the Borrower or its Subsidiaries, as the case may be.

          7.4  Conduct of Business and Maintenance of Existence.  Continue to
               ------------------------------------------------
engage in business of the same general type as now conducted by it and preserve,
renew and keep in full force and effect its corporate existence and take all
reasonable action to maintain all rights, privileges and franchises necessary or
desirable in the normal conduct of its business except as otherwise permitted
pursuant to subsection 8.5; comply with all Contractual Obligations and
Requirements of Law except to the extent that failure to comply therewith could
not, in the aggregate, be reasonably expected to have a Material Adverse Effect.

          7.5  Maintenance of Property; Insurance.  Keep all property useful and
               ----------------------------------
necessary in its business in good working order and condition; maintain with
financially sound and reputable insurance companies insurance on all its
property in at least such amounts and against at least such risks as are usually
insured against in the same general area by companies
<PAGE>

                                                                              40

engaged in the same or a similar business; and furnish to each Lender, upon
written request, full information as to the insurance carried.

          7.6  Inspection of Property; Books and Records; Discussions.  Keep
               ------------------------------------------------------
proper books of records and account in which full, true and correct entries in
conformity with GAAP and all Requirements of Law shall be made of all dealings
and transactions in relation to its business and activities; and permit
representatives of any Lender to visit and inspect any of its properties and
examine and make abstracts from any of its books and records at any reasonable
time (and, in the absence of a Default or an Event of Default, with reasonable
notice) and as often as may reasonably be desired and to discuss the business,
operations, properties and financial and other condition of the Borrower and its
Subsidiaries with officers and employees of the Borrower and its Subsidiaries
and with its independent certified public accountants.

          7.7  Notices.  Promptly give notice to the Administrative Agent and
               -------
each Lender of:

          (a)  the occurrence of any Default or Event of Default;

          (b)  any (i) default or event of default under any Contractual
     Obligation of the Borrower or any of its Subsidiaries or (ii) litigation,
     investigation or proceeding which may exist at any time between the
     Borrower or any of its Subsidiaries and any Governmental Authority, which
     in either case, if not cured or if adversely determined, as the case may
     be, could reasonably be expected to have a Material Adverse Effect;

          (c)  any litigation or proceeding affecting the Borrower or any of its
     Subsidiaries in which the amount involved is $1,000,000 or more and not
     covered by insurance or in which injunctive or similar relief is sought;

          (d)  the following events, as soon as possible and in any event within
     30 days after the Borrower knows or has reason to know thereof: (i) the
     occurrence or expected occurrence of any Reportable Event with respect to
     any Plan, a failure to make any required contribution to a Plan, the
     creation of any Lien in favor of the PBGC or a Plan or any withdrawal from,
     or the termination, Reorganization or Insolvency of, any Multiemployer Plan
     or (ii) the institution of proceedings or the taking of any other action by
     the PBGC or the Borrower or any Commonly Controlled Entity or any
     Multiemployer Plan with respect to the withdrawal from, or the terminating,
     Reorganization or Insolvency of, any Plan;

          (e)  prior to the Collateral Substitution Date, the delivery by Zhone,
     AcquisitionCo or LegacyCo to any Investor of a capital call pursuant to any
     Stock Purchase Agreement; and

          (f)  any development or event which has had or could reasonably be
     expected to have a Material Adverse Effect.

Each notice pursuant to this subsection shall be accompanied by a statement of a
Responsible Officer setting forth details of the occurrence referred to therein
and stating what action the Borrower proposes to take with respect thereto.
<PAGE>

                                                                              41

          7.8  Environmental Laws.  (a)  Comply with, and ensure compliance by
          -----------------------
all tenants and subtenants, if any, with, all applicable Environmental Laws and
obtain and comply in all material respects with and maintain, and ensure that
all tenants and subtenants obtain and comply in all material respects with and
maintain, any and all licenses, approvals, notifications, registrations or
permits required by applicable Environmental Laws, except to the extent that
failure to do so could not be reasonably expected to have a Material Adverse
Effect.

          (b)  Conduct and complete all investigations, studies, sampling and
     testing, and all remedial, removal and other actions required under
     Environmental Laws and promptly comply in all material respects with all
     lawful orders and directives of all Governmental Authorities regarding
     Environmental Laws, except to the extent that the same are being contested
     in good faith by appropriate proceedings and the pendency of such
     proceedings could not be reasonably expected to have a Material Adverse
     Effect.

          7.9  Further Assurances.  Upon the request of the Administrative
          -----------------------
Agent, promptly perform or cause to be performed any and all acts and execute or
cause to be executed any and all documents (including, without limitation,
financing statements and continuation statements) for filing under the
provisions of the Uniform Commercial Code or any other Requirement of Law which
are necessary or reasonably advisable to maintain in favor of the Administrative
Agent, for the benefit of the Lenders, Liens on the Collateral that are duly
perfected in accordance with all applicable Requirements of Law.

          7.10 Additional Collateral.  (a)  With respect to any Person that,
          --------------------------
subsequent to the Closing Date, becomes a Domestic Subsidiary, promptly (and, in
any event, within ten Business Days after such Person becomes a Domestic
Subsidiary):  (i) execute and deliver to the Administrative Agent, for the
benefit of the Lenders, a new pledge agreement or such amendments to the
relevant Security Document as the Administrative Agent reasonably shall deem
necessary or advisable to grant to the Administrative Agent, for the benefit of
the Lenders, a Lien on the Capital Stock of such Subsidiary which is owned by
the Borrower or any of its Subsidiaries, (ii) deliver to the Administrative
Agent the certificates representing such Capital Stock, together with undated
stock powers executed and delivered in blank by a duly authorized officer of the
Borrower or such Subsidiary, as the case may be, (iii) cause such new Subsidiary
(A) to become a party to the Initial Collateral Agreement or the Subsequent
Collateral Agreement, as applicable, in each case pursuant to documentation
which is in form and substance satisfactory to the Administrative Agent, and (B)
to take all actions necessary or advisable to cause the Lien created by the
Initial Collateral Agreement or the Subsequent Collateral Agreement, as
applicable, to be duly perfected in accordance with all applicable Requirements
of Law, including, without limitation, the filing of financing statements in
such jurisdictions as may be requested by the Administrative Agent and (iv) if
requested by the Administrative Agent, deliver to the Administrative Agent legal
opinions relating to the matters described in clauses (i), (ii) and (iii)
immediately preceding, which opinions shall be in form and substance, and from
counsel, reasonably satisfactory to the Administrative Agent.

          (b)  With respect to any Person that, subsequent to the Closing Date,
     becomes a Foreign Subsidiary and which has Capital Stock which is owned
     directly by the Borrower or a Domestic Subsidiary, promptly (and, in any
     event, within 30 days following the date upon which such Person becomes a
     Foreign Subsidiary): (i) execute and deliver to the Administrative Agent a
     new Foreign Pledge Agreement or such
<PAGE>

                                                                              42

     amendments to the relevant Foreign Pledge Agreement as the Administrative
     Agent reasonably shall deem necessary or advisable to grant to the
     Administrative Agent, for the benefit of the Lenders, a Lien on the Capital
     Stock of such Subsidiary which is owned by the Borrower or any of its
     Subsidiaries (provided that in no event shall more than 65% of the Capital
     Stock of any such Subsidiary be required to be so pledged if the pledge of
     more than such amount would be reasonably likely to cause adverse tax
     consequences), (ii) to the extent reasonably deemed advisable by the
     Administrative Agent, deliver to the Administrative Agent any certificates
     representing such Capital Stock, together with undated stock powers
     executed and delivered in blank by a duly authorized officer of the
     Borrower or such Subsidiary, as the case may be, (iii) take or cause to be
     taken all such other actions under the law of the jurisdiction of
     organization of such Foreign Subsidiary as may be necessary or advisable to
     perfect such Lien on such Capital Stock and (iv) if requested by the
     Administrative Agent, deliver to the Administrative Agent legal opinions
     relating to the matters described in clauses (i) through (iii) immediately
     preceding, which opinions shall be in form and substance, and from counsel,
     reasonably satisfactory to the Administrative Agent.

          (c)   In furtherance of the foregoing provisions of this subsection
     7.10, Premisys and each of its Subsidiaries shall, on the Merger Date, be
     deemed to be a Subsidiary of the Borrower and shall comply with the
     provisions of this subsection 7.10; provided that (i) it being understood
     that Premisys and each of its Subsidiaries shall, for purposes of this
     subsection 7.10 only, be deemed not to constitute a Subsidiary of the
     Borrower prior to the Merger Date and (ii) if the Borrower provides to the
     Administrative Agent a certificate of a Responsible Officer certifying that
     the Reorganization Date is anticipated in good faith to occur within 60
     days following the Merger Date, then the Borrower need not comply with the
     provisions of clause (b) of this subsection 7.10 (or any similar
     requirement of any Security Document) until the earlier of the
     Reorganization Date or such 60th day following the Merger Date.
     Notwithstanding the foregoing, the Borrower shall pledge the Capital Stock
     of Premisys which is held by it pursuant to the Initial Collateral
     Agreement from and after the Closing Date.

         7.11  Consummation of Merger.  Cause the Merger to be consummated in
               ----------------------
accordance with the terms of the Acquisition Documents and applicable
Requirements of Law as soon as is practicable following the consummation of the
Tender Offer, and to comply in all material respects with the obligations of the
Borrower and AcquisitionCo under the Acquisition Documents.

                            8.  NEGATIVE COVENANTS

          The Borrower hereby agrees that, so long as any Commitments remain in
effect or any amount is owing to any Lender or the Administrative Agent
hereunder or under any other Credit Document, the Borrower shall not, and
(except with respect to subsection 8.1) shall not permit any of its Subsidiaries
to, directly or indirectly:

         8.1   Financial Condition Covenants.
               -----------------------------

          (a) Minimum Interest Coverage Ratio.  Permit the ratio of (i) EBITDA
          -----------------------------------
     for any period of four consecutive fiscal quarters to (i) Interest Expense
     for such period (excluding any Interest Expense paid in cash on account of
     the Zhone Subordinated Note
<PAGE>

                                                                              43

     pursuant to the provisions of subsection 8.18(a)), to be less than 3.25 to
     1.0; provided that, until the completion of four full fiscal quarters
          --------
     following the Closing Date, (x) EBITDA of the Borrower and its Subsidiaries
     for periods prior to the Closing Date shall be deemed to be equal to the
     actual EBITDA for such periods of the businesses to be held by LegacyCo
     following the Reorganization Date and (y) Interest Expense shall be
     determined on a pro forma basis by annualizing the Interest Expense of the
     Borrower and its Subsidiaries for the period following the Closing Date.

          (b)  Maximum Leverage Ratio.  Permit the ratio of (i) total
          ---------------------------
     Indebtedness of the Borrower and its Subsidiaries (excluding any
     Indebtedness on account of the Zhone Subordinated Note) to (ii) EBITDA for
     the period of four consecutive fiscal quarters ended most recently prior to
     such date, to be greater than the ratio set forth opposite such period
     below:

================================================================================
          Period                                           Ratio
--------------------------  ----------------------------------------------------
 Closing Date - 12/31/03                                3.25 to 1.0

  01/01/04 - thereafter                                 2.50 to 1.0

================================================================================

     ; provided that, until the completion of four full fiscal quarters
       --------
     following the Closing Date, compliance with the provisions of this clause
     (b) shall be determined on a pro forma basis, with (x) the amounts borrowed
     hereunder on the Closing Date being deemed to be outstanding on each day of
     such period prior to the Closing Date and (y) EBITDA of the Borrower and
     its Subsidiaries for periods prior to the Closing Date being deemed to be
     equal to the actual EBITDA for such periods of the businesses to be held by
     LegacyCo following the Reorganization Date.

         8.2   Limitation on Indebtedness.  Create, incur, assume or suffer to
               --------------------------
exist any Indebtedness (including, in any event, any preferred stock), except:

         (a)   Indebtedness of the Borrower under this Agreement;

         (b)   Indebtedness of the Borrower to any Subsidiary and of any
     Subsidiary to the Borrower or any other Subsidiary;

         (c)    Indebtedness of the Borrower and any of its Subsidiaries
     incurred to finance the acquisition of fixed or capital assets (whether
     pursuant to a loan, a Financing Lease or otherwise) in an aggregate
     principal amount not exceeding as to the Borrower and its Subsidiaries
     $500,000 at any time outstanding;

         (d)    Indebtedness outstanding on the date hereof and listed on
     Schedule 8.2 and any refinancings, refundings, renewals or extensions
     thereof;
<PAGE>

                                                                              44

          (e)  Prior to the Reorganization Date, Indebtedness of the Borrower
     owing to Zhone which is evidenced by a Zhone Subordinated Note; and

          (f)  Additional Indebtedness not exceeding $500,000 in aggregate
     principal amount at any one time outstanding.

          8.3  Limitation on Liens.  Create, incur, assume or suffer to exist
          ------------------------
any Lien upon any of its property, assets or revenues, whether now owned or
hereafter acquired, except for:

          (a)  Liens for taxes not yet due or which are being contested in good
     faith by appropriate proceedings, provided that adequate reserves with
                                       --------
     respect thereto are maintained on the books of the Borrower or its
     Subsidiaries, as the case may be, in conformity with GAAP (or, in the case
     of Foreign Subsidiaries, generally accepted accounting principles in effect
     from time to time in their respective jurisdictions of incorporation);

          (b)  carriers', warehousemen's, mechanics', materialmen's, repairmen's
     or other like Liens arising in the ordinary course of business which are
     not overdue for a period of more than 60 days or which are being contested
     in good faith by appropriate proceedings;

          (c)  pledges or deposits in connection with workers' compensation,
     unemployment insurance and other social security legislation and deposits
     securing liability to insurance carriers under insurance or self-insurance
     arrangements;

          (d)  deposits to secure the performance of bids, trade contracts
     (other than for borrowed money), leases, statutory obligations, surety and
     appeal bonds, performance bonds and other obligations of a like nature
     incurred in the ordinary course of business;

          (e)  easements, rights-of-way, restrictions and other similar
     encumbrances incurred in the ordinary course of business which, in the
     aggregate, are not substantial in amount and which do not in any case
     materially detract from the value of the property subject thereto or
     materially interfere with the ordinary conduct of the business of the
     Borrower or such Subsidiary;

          (f)  Liens in existence on the date hereof listed on Schedule 8.3,
     securing Indebtedness permitted by subsection 8.2(d), provided that no such
                                                           --------
     Lien is spread to cover any additional property after the Closing Date and
     that the amount of Indebtedness secured thereby is not increased;

          (g)  Liens securing Indebtedness of the Borrower and its Subsidiaries
     permitted by subsection 8.2(c) incurred to finance the acquisition of fixed
     or capital assets, provided that (i) such Liens shall be created
                        --------
     substantially simultaneously with the acquisition of such fixed or capital
     assets, (ii) such Liens do not at any time encumber any property other than
     the property financed by such Indebtedness and (iii) the amount of
     Indebtedness secured thereby is not increased;

          (h)  Liens (not otherwise permitted hereunder) which secure
     Indebtedness not exceeding (as to the Borrower and all Subsidiaries)
     $500,000 in aggregate amount at any time outstanding; and
<PAGE>

                                                                              45

          (i)   Liens created pursuant to the Security Documents.

          8.4   Limitation on Guarantee Obligations.  Create, incur, assume or
          -----------------------------------------
suffer to exist any Guarantee Obligation except:

          (a)  Guarantee Obligations in existence on the date hereof and listed
               on Schedule 8.4;

          (b)  Guarantee Obligations incurred after the date hereof supporting
               Indebtedness in an aggregate amount not to exceed $500,000 at any
               one time outstanding;

          (c)  Guarantees made in the ordinary course of its business by the
               Borrower or (prior to the Merger Date, at which time Premisys
               will become the Borrower) Premisys of obligations of any of its
               Subsidiaries, which obligations are otherwise permitted under
               this Agreement; and

          (d)  the Security Documents.

          8.5  Limitation on Fundamental Changes.  Enter into any merger,
          --------------------------------------
consolidation or amalgamation, or liquidate, wind up or dissolve itself (or
suffer any liquidation or dissolution), or convey, sell, lease, assign, transfer
or otherwise dispose of, all or substantially all of its property, business or
assets, or make any material change in its present method of conducting
business, except:

               (a)    the Merger and the Asset Transfer;

               (b)    any Subsidiary of the Borrower may be merged or
          consolidated with or into the Borrower (provided that the Borrower
                                                  --------
          shall be the continuing or surviving corporation) or with or into any
          one or more wholly owned Subsidiaries of the Borrower (provided that
                                                                 --------
          the wholly owned Subsidiary or Subsidiaries shall be the continuing or
          surviving corporation); and

               (c)    any Subsidiary may sell, lease, transfer or otherwise
          dispose of any or all of its assets (upon voluntary liquidation or
          otherwise) to the Borrower or any other wholly owned Subsidiary of the
          Borrower.

          8.6  Limitation on Sale of Assets.  Convey, sell, lease, assign,
          ---------------------------------
transfer or otherwise dispose of any of its property, business or assets
(including, without limitation, receivables and leasehold interests), whether
now owned or hereafter acquired, or, in the case of any Subsidiary, issue or
sell any shares of such Subsidiary's Capital Stock to any Person other than the
Borrower or any wholly owned Subsidiary, except:

          (a)  the sale or other disposition of obsolete or worn out property in
     the ordinary course of business;

          (b)  the sale of inventory in the ordinary course of business;
<PAGE>

                                                                              46

          (c)  the sale or other disposition of any property (other than assets
     described in clauses (a) and (b) above) in the ordinary course of business,
     provided that the aggregate book value of all assets so sold or disposed of
     --------
     in any period of twelve consecutive months shall not exceed $1,000,000;

          (d)  the sale or discount without recourse of accounts receivable
     arising in the ordinary course of business in connection with the
     compromise or collection thereof;

          (e)  as permitted by subsection 8.5;

          (f)  the sale, transfer or other disposition of assets to LegacyCo and
     its Subsidiaries pursuant to the Asset Transfer;

          (g)  the sale, transfer or other disposition of intellectual property
     to Affiliates of the Borrower; provided that each Affiliate to which any
     such intellectual property is transferred (whether from the Borrower, any
     Subsidiary or any other Affiliate) shall have executed and delivered to the
     Administrative Agent a License Letter;

          (h)  the sale, transfer or other disposition of raw materials and
     work-in-process inventory of LegacyCo (or, prior to the Reorganization
     Date, of businesses which, after the Reorganization Date, will constitute a
     part of LegacyCo) to contract manufacturers who will be utilized by the
     Borrower to manufacture inventory for LegacyCo; and

          (i)  the sale of the manufacturing assets of the Borrower and its
     Subsidiaries.

          8.7  Limitation on Leases.  Permit the aggregate amount of fixed and
          -------------------------
contingent rentals payable by LegacyCo (including, for periods prior to the
Reorganization Date, any such amounts payable by AcquisitionCo and Premisys on
account of the assets and business which will comprise LegacyCo) in any fiscal
year of the Borrower with respect to leases of real and personal property
(determined on a consolidated basis in accordance with GAAP) to exceed
$3,500,000.

          8.8  Limitation on Restricted Payments.  Declare or pay any dividend
          --------------------------------------
(other than dividends payable solely in common stock of the Borrower) on, or
make any payment on account of, or set apart assets for a sinking or other
analogous fund for, the purchase, redemption, defeasance, retirement or other
acquisition of, any shares of any class of Capital Stock of the Borrower or any
warrants or options to purchase any such Stock, whether now or hereafter
outstanding, or make any other distribution in respect thereof, either directly
or indirectly, whether in cash or property or in obligations of the Borrower or
any Subsidiary (a "Restricted Payment"); provided that,
                   ------------------

          (a)  during such time as no Default or Event of Default has occurred
     and is continuing, the Borrower may make Restricted Payments in an amount
     not to exceed the tax liabilities which would have been payable to
     Governmental Authorities by the Borrower and its Subsidiaries on a stand-
     alone basis if they were not members of a consolidated group taxpayer group
     with Zhone (but net of any such liabilities which are
<PAGE>

                                                                              47

     payable directly by the Borrower and its Subsidiaries as members of such
     consolidated taxpayer group); and

          (b)  during any such time as any Default or Event of Default is
     continuing, the Borrower may make Restricted Payments in an amount not to
     exceed the tax liabilities which are payable by Zhone to Governmental
     Authorities within 30 days following the date of such Restricted Payment
     and which would have been payable by the Borrower and its Subsidiaries on a
     stand-alone basis if they were not members of a consolidated group taxpayer
     group with Zhone (but net of any such liabilities which are payable
     directly by the Borrower and its Subsidiaries as members of such
     consolidated taxpayer group).

          8.9  Limitation on Capital Expenditures.  Make or commit to make (by
          ---------------------------------------
way of the acquisition of securities of a Person or otherwise) any expenditure
in respect of the purchase or other acquisition of fixed or capital assets
(excluding any such asset acquired in connection with normal replacement and
maintenance programs properly charged to current operations) except for
expenditures in the ordinary course of business not exceeding, in the aggregate
for the Borrower and its Subsidiaries, $1,000,000 during any fiscal year of the
Borrower; provided that any portion of such amount which is not so expended in
          --------
the fiscal year for which it is permitted above may be carried-over to increase
the amount permitted for the next fiscal year of the Borrower (and shall be
deemed to be the last amounts expended in such next fiscal year).

          8.10 Limitation on Investments, Loans and Advances.  Make any advance,
          --------------------------------------------------
loan, extension of credit or capital contribution to, or purchase any stock,
bonds, notes, debentures or other securities of or any assets constituting a
business unit of, or make any other investment in, any Person, except :

          (a)  extensions of trade credit in the ordinary course of business;

          (b)  investments in Cash Equivalents;

          (c)  the Asset Transfer;

          (d)  loans and advances to employees of the Borrower or its
     Subsidiaries for travel, entertainment and relocation expenses in the
     ordinary course of business in an aggregate amount for the Borrower and its
     Subsidiaries not to exceed $150,000 at any one time outstanding and
     additional loans and advances to employees which exist on the Closing Date;

          (e)  investments by the Borrower in, and loans, advances and capital
     contributions by the Borrower to, its Subsidiaries and investments by such
     Subsidiaries in, and loans, advances and capital contributions by
     Subsidiaries to, the Borrower and other Subsidiaries;

          (f)  loans made by the Borrower to Zhone or Premisys at any time when
     no Default or Event of Default is continuing in an aggregate principal
     amount for any fiscal year of the Borrower not to exceed the amount equal
     to 100% of Excess Cash Flow for the fiscal year of the Borrower most
     recently ended minus the aggregate amount of repayments made by the
     Borrower of amounts owing under the Zhone Subordinated Note made during the
     current fiscal year; provided that (i) for the fiscal year during which the
<PAGE>

                                                                              48

     Closing Date and the Reorganization occur, Excess Cash Flow shall be
     determined on a pro forma basis as if the Closing Date, the Reorganization
     and the other transactions contemplated hereby had occurred on the first
     day of such fiscal year and (ii) any such loans shall be subordinated to
     the other obligations of Zhone or Premisys (as the case may be) upon terms
     reasonably satisfactory to the Administrative Agent and shall be evidenced
     by promissory notes which are delivered to the Administrative Agent and
     pledged pursuant to the Subsequent Collateral Agreement;

          (g)  additional investments, loans and advances to the extent that
     the sum of (i) the aggregate principal amount of such investments and loans
     at any one time outstanding and (ii) the aggregate amount of such
     investments made since the Closing Date, does not exceed $500,000 in the
     aggregate.

          8.11 Limitation on Transactions with Affiliates.  Enter into any
          -----------------------------------------------
transaction, including, without limitation, any purchase, sale, lease or
exchange of property or the rendering of any service, with any Affiliate unless
such transaction is (a) otherwise permitted under this Agreement, (b) in the
ordinary course of the Borrower's or such Subsidiary's business and (c) upon
fair and reasonable terms no less favorable to the Borrower or such Subsidiary,
as the case may be, than it would obtain in a comparable arm's length
transaction with a Person which is not an Affiliate; provided that nothing
contained in this subsection 8.11 shall be deemed to prohibit (i) the
consummation of the Asset Transfer or (ii) the payment of amounts owing under
tax sharing agreements with Affiliates to the extent that such amounts are
permitted to be paid pursuant to subsection 8.8.

          8.12 Limitation on Sales and Leasebacks.  Enter into any arrangement
          ---------------------------------------
with any Person providing for the leasing by the Borrower or any Subsidiary of
real or personal property which has been or is to be sold or transferred by the
Borrower or such Subsidiary to such Person or to any other Person to whom funds
have been or are to be advanced by such Person on the security of such property
or rental obligations of the Borrower or such Subsidiary.

          8.13 Limitation on Changes in Fiscal Year.  Permit the fiscal year of
          ------------------------------------------
LegacyCo to end on a day other than December 31.

          8.14 Limitation on Negative Pledge Clauses.  Enter into with any
          -------------------------------------------
Person any agreement which prohibits or limits the ability of the Borrower or
any of its Subsidiaries to create, incur, assume or suffer to exist any Lien
upon any of its property, assets or revenues, whether now owned or hereafter
acquired, other than (a) this Agreement, (b) any lease agreement which restricts
the granting of Liens upon the property leased to the Borrower and its
Subsidiaries thereunder from an unaffiliated third party (it being understood
that the License Letter shall in no event constitute such a lease agreement) and
(c) any agreement governing the sale, transfer or other disposition of property
to an unaffiliated third party in accordance with the terms of this Agreement
which restricts the granting of Liens upon the property to be sold, transferred
or otherwise disposed of thereunder.

          8.15 Limitation on Lines of Business.  Enter into any business,
          ------------------------------------
either directly or through any Subsidiary, except for those businesses in which
the Borrower and its Subsidiaries are engaged on the date of this Agreement or
which are directly related thereto.
<PAGE>

                                                                              49

          8.16 Rights under Acquisition Documents. Amend, supplement or
               ----------------------------------
otherwise modify (including any waiver thereof) the Acquisition Documents in any
material respect, without the prior written consent of the Majority Lenders.

          8.17 Asset Transfer.  Consummate the Asset Transfer or permit the
          -------------------
Reorganization Date to occur, unless:

          (a)  the Administrative Agent has received counterparts of (i) each of
     the Security Documents to be in effect after the Reorganization Date,
     executed and delivered by a duly authorized officer of each Credit Party
     which is a party thereto and (ii) the Assumption Agreement, executed and
     delivered by a duly authorized officer of LegacyCo; by its execution of
     this Agreement, each Lender hereby authorizes and instructs the
     Administrative Agent to execute and deliver the Assumption Agreement and
     agrees to be bound by the terms of the Assumption Agreement;

          (b)  The Administrative Agent shall have received (i) the certificates
     representing the shares pledged pursuant to each of the Security Documents,
     together with an undated stock power for each such certificate executed in
     blank by a duly authorized officer of the pledgor thereof and (ii) evidence
     in form and substance satisfactory to it that all filings, recordings,
     registrations and other actions, including, without limitation, the filing
     of duly executed financing statements on form UCC-1, necessary or, in the
     opinion of the Administrative Agent, desirable to perfect the Liens created
     by the Security Documents shall have been completed;

          (c)  to the extent not previously received pursuant to the provisions
     of Section 6.1, the Administrative Agent shall have received, with a
     counterpart for each Lender, (i) a true and complete copy of the
     certificate of incorporation (or analogous document) of each Credit Party,
     (ii) a true and complete copy of the By-laws (or analogous document) of
     each Credit Party and (iii) a true and complete copy of the resolutions of
     the Board of Directors (or analogous document) of each Credit Party
     authorizing (A) the execution, delivery and performance by such Credit
     Party of the Credit Documents to which it is a party, (B) in the case of
     the Borrower, the assumption of the Loans and other obligations
     contemplated hereunder and (C) the granting by such Credit Party of any
     Liens purported to be created by it pursuant to the Security Documents.
     Such documents shall be certified by the Secretary or an Assistant
     Secretary of such Credit Party (or, if such credit party is not a
     corporation, a duly authorized general partner or member thereof) as of the
     Reorganization Date, which certificate shall (w) be in form and substance
     reasonably satisfactory to the Administrative Agent, (x) certify that such
     documents are true and correct copies of the originals thereof, (y) certify
     as to the incumbency and signature of the officers of such Credit Party
     executing any Credit Document and (z) state that the resolutions (or
     analogous authorizations) described in clause (iii) above have not been
     amended, modified, revoked or rescinded;

          (d)  the Administrative Agent has received from Latham & Watkins
     and/or other acceptable counsel to Zhone, the Borrower and the other Credit
     Parties an executed legal opinion which is in form and substance reasonably
     satisfactory to the Administrative Agent;
<PAGE>

                                                                              50

          (e)  Premisys shall own 100% of the equity interests (on a fully
     diluted basis) in LegacyCo.  Schedule 8.17 hereto shall list all
     Subsidiaries of LegacyCo immediately after giving effect to the Asset
     Transfer and the percentage of the equity interests of such Subsidiary
     which is owned by LegacyCo;

          (f)  after giving effect to the occurrence of the Reorganization Date,
     each of the representations and warranties contained in this Agreement and
     in the other Credit Documents contemplated to be in effect after the
     Reorganization Date shall be true and correct in all material respects; and

          (g)  the Administrative Agent shall have received a true and correct
     copy of written instructions from LegacyCo to each Investor specifying that
     all payments made by such Investor to LegacyCo on account of the Assigned
     Interests shall be paid directly into the Cash Collateral Account (as
     defined in the LegacyCo Cash Collateral Agreement); such instructions shall
     (x) be irrevocable and unconditional, (y) unless such acknowledgment and
     consent is provided in the Capital Call Agreement to which such Investor is
     a party, contain a duly executed and delivered acknowledgment and consent
     from each Investor and (z) be in form and substance reasonably satisfactory
     to the Administrative Agent; and

          (h)  the principal of and accrued interest on the Acquisition Loans
     shall have been paid in full.

From and after the Reorganization Date, Zhone shall have no further obligations
or liabilities hereunder or under any other Credit Document which is to
terminate on such date pursuant to subsection 11.2 hereof.

          8.18 Optional Payments and Modifications of Certain Debt Instruments.
          ---------------------------------------------------------------------
(a)  Make or offer to make any optional or voluntary payment, prepayment,
repurchase or redemption of or otherwise optionally or voluntarily defease or
segregate funds with respect to the obligations (including, without limitation,
Interest Expense on account thereof) evidenced by the Zhone Subordinated Note,
other than, during such time as no Default or Event of Default is continuing or
would result therefrom, (i) payments made with the proceeds of the Loans
hereunder within one Business Day following the borrowing of such Loans and (ii)
payments made with the proceeds received by Premisys on account of the sale to
AcquisitionCo of Capital Stock of Premisys pursuant to the Company Option
Agreement described in the Merger Agreement.

          (b)  Prior to the Reorganization Date, amend, modify, waive or
otherwise change, or consent or agree to any amendment, modification, waiver or
other change to, any of the terms of the Zhone Subordinated Note or the
obligations of the Borrower evidenced thereby.

                         SECTION 9 EVENTS OF DEFAULT

          If any of the following events shall occur and be continuing:

          (a)  The Borrower shall fail to pay any principal of any Loan when due
     in accordance with the terms thereof or hereof; or the Borrower shall fail
     to pay any interest
<PAGE>

                                                                              51

     on any Loan, or any other amount payable hereunder, within five days after
     any such interest or other amount becomes due in accordance with the terms
     thereof or hereof; or

          (b)  Any representation or warranty made or deemed made by the
     Borrower or any other Credit Party herein or in any other Credit Document
     or which is contained in any certificate, document or financial or other
     statement furnished by it at any time under or in connection with this
     Agreement or any such other Credit Document shall prove to have been
     incorrect in any material respect on or as of the date made or deemed made;
     or

          (c)  The Borrower or any other Credit Party shall default in the
     observance or performance of any agreement contained in Section 8;

          (d)  The Borrower or any other Credit Party shall default in the
     observance or performance of any other agreement contained in this
     Agreement or any other Credit Document (other than as provided in
     paragraphs (a) through (c) of this Section 9), and such default shall
     continue unremedied or unwaived for a period of 30 days; or

          (e)  The Borrower or any of its Subsidiaries shall (i) default in any
     payment of principal of or interest on any Indebtedness (other than the
     Loans) or in the payment of any Guarantee Obligation, beyond the period of
     grace (not to exceed 30 days), if any, provided in the instrument or
     agreement under which such Indebtedness or Guarantee Obligation was
     created; or (ii) default in the observance or performance of any other
     agreement or condition relating to any such Indebtedness or Guarantee
     Obligation or contained in any instrument or agreement evidencing, securing
     or relating thereto, or any other event shall occur or condition exist, the
     effect of which default or other event or condition is to cause, or to
     permit the holder or holders of such Indebtedness or beneficiary or
     beneficiaries of such Guarantee Obligation (or a trustee or Administrative
     Agent on behalf of such holder or holders or beneficiary or beneficiaries)
     to cause, with the giving of notice if required, such Indebtedness to
     become due prior to its stated maturity or such Guarantee Obligation to
     become payable; provided, however, that no Default or Event of Default
                     --------  -------
     shall exist under this paragraph unless the aggregate amount of
     Indebtedness and/or Guarantee Obligations in respect of which any default
     or other event or condition referred to in this paragraph shall have
     occurred shall be equal to at least $250,000; or

          (f)  (i)  The Borrower or any of its Subsidiaries or, prior to the
     Reorganization Date, Zhone shall commence any case, proceeding or other
     action (A) under any existing or future law of any jurisdiction, domestic
     or foreign, relating to bankruptcy, insolvency, reorganization or relief of
     debtors, seeking to have an order for relief entered with respect to it, or
     seeking to adjudicate it a bankrupt or insolvent, or seeking
     reorganization, arrangement, adjustment, winding-up, liquidation,
     dissolution, composition or other relief with respect to it or its debts,
     or (B) seeking appointment of a receiver, trustee, custodian, conservator
     or other similar official for it or for all or any substantial part of its
     assets, or the Borrower or any of its Subsidiaries or, prior to the
     Reorganization Date, Zhone shall make a general assignment for the benefit
     of its creditors; or (ii) there shall be commenced against the Borrower or
     any of its Subsidiaries or, prior to the Reorganization Date, Zhone any
     case, proceeding or other action of a nature referred to in clause (i)
     above which (A) results in the entry of an order for relief or any such
<PAGE>

                                                                              52

     adjudication or appointment or (B) remains undismissed, undischarged or
     unbonded for a period of 60 days; or (iii) there shall be commenced against
     the Borrower or any of its Subsidiaries or, prior to the Reorganization
     Date, Zhone any case, proceeding or other action seeking issuance of a
     warrant of attachment, execution, distraint or similar process against all
     or any substantial part of its assets which results in the entry of an
     order for any such relief which shall not have been vacated, discharged, or
     stayed or bonded pending appeal within 60 days from the entry thereof; or
     (iv) the Borrower or any of its Subsidiaries or, prior to the
     Reorganization Date, Zhone shall take any action in furtherance of, or
     indicating its consent to, approval of, or acquiescence in, any of the acts
     set forth in clause (i), (ii), or (iii) above; or (v) the Borrower or any
     of its Subsidiaries or, prior to the Reorganization Date, Zhone shall
     generally not, or shall be unable to, or shall admit in writing its
     inability to, pay its debts as they become due; or

          (g)  (i)  Any Person shall engage in any "prohibited transaction" (as
     defined in Section 406 of ERISA or Section 4975 of the Code) involving any
     Plan, (ii) any "accumulated funding deficiency" (as defined in Section 302
     of ERISA), whether or not waived, shall exist with respect to any Plan or
     any Lien in favor of the PBGC or a Plan shall arise on the assets of the
     Borrower or any Commonly Controlled Entity, (iii) a Reportable Event shall
     occur with respect to, or proceedings shall commence to have a trustee
     appointed, or a trustee shall be appointed, to administer or to terminate,
     any Single Employer Plan, which Reportable Event or commencement of
     proceedings or appointment of a trustee is, in the reasonable opinion of
     the Majority Lenders, likely to result in the termination of such Plan for
     purposes of Title IV of ERISA, (iv) any Single Employer Plan shall
     terminate for purposes of Title IV of ERISA, (v) the Borrower or any
     Commonly Controlled Entity shall, or in the reasonable opinion of the
     Majority Lenders is likely to, incur any liability in connection with a
     withdrawal from, or the Insolvency or Reorganization of, a Multiemployer
     Plan or (vi) any other event or condition shall occur or exist with respect
     to a Plan; and in each case in clauses (i) through (vi) above, such event
     or condition, together with all other such events or conditions, if any,
     involve an aggregate amount in excess of $1,000,000; or

          (h)  One or more judgments or decrees shall be entered against the
     Borrower or any of its Subsidiaries involving in the aggregate a liability
     (not paid or fully covered by insurance) of $1,000,000 or more, and all
     such judgments or decrees shall not have been vacated, discharged, stayed
     or bonded pending appeal within 60 days from the entry thereof; or

          (i)  (i)  Any of the Security Documents or the Premisys Escrow
     Agreement (or any material provision of any thereof) shall cease, for any
     reason (other than pursuant to the express terms thereof or of subsection
     11.2 hereof), to be in full force and effect, or the Borrower or any other
     Credit Party which is a party to any of the Security Documents shall so
     assert or (ii) the Lien created by any of the Security Documents shall
     cease to be enforceable and of the same effect and priority purported to be
     created thereby; or
<PAGE>

                                                                              53

          (j)  At any time, Zhone shall cease to beneficially own, directly or
     indirectly, 100% of the issued and outstanding Capital Stock of the
     Borrower; or

          (k)  At any time prior to the Collateral Substitution Date, any of (i)
     the Capital Call Agreement to which any Investor is a party (or any
     material provision of any thereof) shall cease, for any reason, to be in
     full force and effect, or Zhone, the Borrower, any other Credit Party or
     the relevant Investor shall so assert, (ii) any capital commitment
     constituting an Assigned Interest shall cease to be enforceable by the
     Borrower or the Administrative Agent against the Investor with respect
     thereto or (iii) any Capital Call Agreement shall have a remaining term of
     less than 45 days; unless, in any such case, another Investor shall have
     assumed the obligations of the relevant Investor under the Capital Call
     Agreement to which it is a party pursuant to documentation which is in form
     and substance reasonably satisfactory to the Administrative Agent; or

          (l)  At any time prior to the Collateral Substitution Date, any of (i)
     any Capital Call Agreement or the Assignment of Capital Call Rights shall
     be amended, supplemented or otherwise modified without the prior written
     consent of the Administrative Agent, (ii) any of Zhone Investors I, L.L.C.,
     Zhone Investors II, L.L.C. or Zhone Investors III, L.L.C. shall fail to pay
     any amounts owing by it under the Stock Purchase Agreement to which it is a
     party, (iii) the Assignment of Capital Call Rights (or any material
     provision of any thereof) shall cease, for any reason, to be in full force
     and effect, or Zhone, the Borrower or any other Credit Party shall so
     assert, (iv) the amount remaining available to be drawn in respect of the
     Assigned Interests is less than 120% of the aggregate then-outstanding
     principal amount of the Term Loans or (v) any amount payable on account of
     any Assigned Interest shall be paid by the relevant Investor to an account
     other than the Cash Collateral Account (as defined in the AcquisitionCo
     Cash Collateral Agreement or the LegacyCo Cash Collateral Agreement, as
     then applicable); or

          (m)  At any date from and after the Collateral Substitution Date, the
     fair market value of the collateral held in the Cash Collateral Account (as
     defined in the AcquisitionCo Cash Collateral Agreement or the LegacyCo Cash
     Collateral Agreement, as then applicable) is less than 120% of the
     aggregate then-outstanding principal amount of the Term Loans; or

          (n)  The Reorganization Date does not occur on or prior to the date
     which is 60 days after the Merger Date;

then, and in any such event, (A) if such event is an Event of Default specified
in clause (i) or (ii) of paragraph (f) of this Section 9 with respect to the
Borrower, automatically the Commitments shall immediately terminate and the
Loans hereunder (with accrued interest thereon) and all other amounts owing
under this Agreement shall immediately become due and payable, and (B) if such
event is any other Event of Default, either or both of the following actions may
be taken:  (i) with the consent of the Majority Lenders, the Administrative
Agent may, or upon the request of the Majority Lenders, the Administrative Agent
shall, by notice to the Borrower declare the Commitments to be terminated
forthwith, whereupon the Commitments shall immediately terminate; and (ii) with
the consent of the Majority Lenders, the Administrative Agent may, or upon the
request of the Majority Lenders, the Administrative Agent shall, by notice to
the
<PAGE>

                                                                              54

Borrower, declare the Loans hereunder (with accrued interest thereon) and
all other amounts owing under this Agreement to be due and payable forthwith,
whereupon the same shall immediately become due and payable.

          Except as expressly provided above in this Section 9, presentment,
demand, protest and all other notices of any kind are hereby expressly waived.

                      SECTION 10 THE ADMINISTRATIVE AGENT

         10.1  Appointment.  Each Lender hereby irrevocably designates and
               -----------
appoints the Administrative Agent as the agent of such Lender under this
Agreement and the other Credit Documents, and each such Lender irrevocably
authorizes the Administrative Agent, in such capacity, to take such action on
its behalf under the provisions of this Agreement and the other Credit Documents
and to exercise such powers and perform such duties as are expressly delegated
to the Administrative Agent by the terms of this Agreement and the other Credit
Documents, together with such other powers as are reasonably incidental thereto.
Notwithstanding any provision to the contrary elsewhere in this Agreement, the
Administrative Agent shall not have any duties or responsibilities, except those
expressly set forth herein, or any fiduciary relationship with any Lender, and
no implied covenants, functions, responsibilities, duties, obligations or
liabilities shall be read into this Agreement or any other Credit Document or
otherwise exist against the Administrative Agent.

         10.2  Delegation of Duties.  The Administrative Agent may execute any
               --------------------
of its duties under this Agreement and the other Credit Documents by or through
agents or attorneys-in-fact and shall be entitled to advice of counsel
concerning all matters pertaining to such duties.  The Administrative Agent
shall not be responsible for the negligence or misconduct of any agent or
attorneys in-fact selected by it with reasonable care.

         10.3  Exculpatory Provisions.  Neither the Administrative Agent nor any
         ----------------------------
of its officers, directors, employees, agents, attorneys-in-fact or Affiliates
shall be (i) liable for any action lawfully taken or omitted to be taken by it
or such Person under or in connection with this Agreement or any other Credit
Document (except for its or such Person's own gross negligence or willful
misconduct) or (ii) responsible in any manner to any of the Lenders for any
recitals, statements, representations or warranties made by the Borrower or any
officer thereof contained in this Agreement or any other Credit Document or in
any certificate, report, statement or other document referred to or provided for
in, or received by the Administrative Agent under or in connection with, this
Agreement or any other Credit Document or for the value, validity,
effectiveness, genuineness, enforceability or sufficiency of this Agreement or
any other Credit Document or for any failure of the Borrower to perform its
obligations hereunder or thereunder.  The Administrative Agent shall not be
under any obligation to any Lender to ascertain or to inquire as to the
observance or performance of any of the agreements contained in, or conditions
of, this Agreement or any other Credit Document, or to inspect the properties,
books or records of the Borrower.

         10.4  Reliance by Administrative Agent.  The Administrative Agent shall
         --------------------------------------
be entitled to rely, and shall be fully protected in relying, upon any Note,
writing, resolution, notice, consent, certificate, affidavit, letter, telecopy,
telex or teletype message, statement, order or other document or conversation
believed by it to be genuine and correct and to have been signed, sent
<PAGE>

                                                                              55

or made by the proper Person or Persons and upon advice and statements of legal
counsel (including, without limitation, counsel to the Borrower), independent
accountants and other experts selected by the Administrative Agent. The
Administrative Agent may deem and treat the payee of any Note as the owner
thereof for all purposes unless a written notice of assignment, negotiation or
transfer thereof shall have been filed with the Administrative Agent. The
Administrative Agent shall be fully justified in failing or refusing to take any
action under this Agreement or any other Credit Document unless it shall first
receive such advice or concurrence of the Majority Lenders as it deems
appropriate or it shall first be indemnified to its satisfaction by the Lenders
against any and all liability and expense which may be incurred by it by reason
of taking or continuing to take any such action. The Administrative Agent shall
in all cases be fully protected in acting, or in refraining from acting, under
this Agreement and the other Credit Documents in accordance with a request of
the Majority Lenders (or such larger number of Lenders as may be explicitly
required hereunder), and such request and any action taken or failure to act
pursuant thereto shall be binding upon all the Lenders and all future holders of
the Loans.

         10.5  Notice of Default.  The Administrative Agent shall not be deemed
         -----------------------
to have knowledge or notice of the occurrence of any Default or Event of Default
hereunder unless the Administrative Agent has received notice from a Lender or
the Borrower referring to this Agreement, describing such Default or Event of
Default and stating that such notice is a "notice of default".  In the event
that the Administrative Agent receives such a notice, the Administrative Agent
shall give notice thereof to the Lenders.  The Administrative Agent shall take
such action with respect to such Default or Event of Default as shall be
reasonably directed by the Majority Lenders; provided that unless and until the
                                             --------
Administrative Agent shall have received such directions, the Administrative
Agent may (but shall not be obligated to) take such action, or refrain from
taking such action, with respect to such Default or Event of Default as it shall
deem advisable in the best interests of the Lenders.

         10.6  Non-Reliance on Administrative Agent and Other Lenders.  Each
         ------------------------------------------------------------
Lender expressly acknowledges that neither the Administrative Agent nor any of
its officers, directors, employees, agents, attorneys-in-fact or Affiliates has
made any representations or warranties to it and that no act by the
Administrative Agent hereinafter taken, including any review of the affairs of
the Borrower, shall be deemed to constitute any representation or warranty by
the Administrative Agent to any Lender.  Each Lender represents to the
Administrative Agent that it has, independently and without reliance upon the
Administrative Agent or any other Lender, and based on such documents and
information as it has deemed appropriate, made its own appraisal of and
investigation into the business, operations, property, financial and other
condition and creditworthiness of the Borrower and made its own decision to make
its Loans hereunder and enter into this Agreement.  Each Lender also represents
that it will, independently and without reliance upon the Administrative Agent
or any other Lender, and based on such documents and information as it shall
deem appropriate at the time, continue to make its own credit analysis,
appraisals and decisions in taking or not taking action under this Agreement and
the other Credit Documents, and to make such investigation as it deems necessary
to inform itself as to the business, operations, property, financial and other
condition and creditworthiness of the Borrower.  Except for notices, reports and
other documents expressly required to be furnished to the Lenders by the
Administrative Agent hereunder, the Administrative Agent shall not have any duty
or responsibility to provide any Lender with any credit or other information
concerning the business, operations, property, condition (financial or
otherwise), prospects or creditworthiness
<PAGE>

                                                                              56

of the Borrower which may come into the possession of the Administrative Agent
or any of its officers, directors, employees, agents, attorneys-in-fact or
Affiliates.

         10.7  Indemnification.  The Lenders agree to indemnify the
         ---------------------
Administrative Agent in its capacity as such (to the extent not reimbursed by
the Borrower and without limiting the obligation of the Borrower to do so),
ratably according to their respective Commitment Percentages in effect on the
date on which indemnification is sought, from and against any and all
liabilities, obligations, losses, damages, penalties, actions, judgments, suits,
costs, expenses or disbursements of any kind whatsoever which may at any time
(including, without limitation, at any time following the payment of the Loans)
be imposed on, incurred by or asserted against the Administrative Agent in any
way relating to or arising out of, the Commitments, this Agreement, any of the
other Credit Documents or any documents contemplated by or referred to herein or
therein or the transactions contemplated hereby or thereby or any action taken
or omitted by the Administrative Agent under or in connection with any of the
foregoing; provided that no Lender shall be liable for the payment of any
           --------
portion of such liabilities, obligations, losses, damages, penalties, actions,
judgments, suits, costs, expenses or disbursements resulting from the
Administrative Agent's gross negligence or willful misconduct.  The agreements
in this subsection shall survive the payment of the Loans and all other amounts
payable hereunder.

         10.8  Administrative Agent in Its Individual Capacity.  The
         ------------------------------------------------------
Administrative Agent and its Affiliates may make loans to, accept deposits from
and generally engage in any kind of business with the Borrower as though the
Administrative Agent were not the Administrative Agent hereunder and under the
other Credit Documents.  With respect to the Loans made by it, the
Administrative Agent shall have the same rights and powers under this Agreement
and the other Credit Documents as any Lender and may exercise the same as though
it were not the Administrative Agent, and the terms "Lender" and "Lenders" shall
include the Administrative Agent in its individual capacity.

         10.9  Successor Administrative Agent.  The Administrative Agent may
         -------------------------------------
resign as Administrative Agent upon 10 days' notice to the Lenders.  If the
Administrative Agent shall resign as "Administrative Agent" under this Agreement
and the other Credit Documents, then the Majority Lenders shall appoint from
among the Lenders a successor Administrative Agent for the Lenders, which
successor Administrative Agent (provided that, to the extent that no Default or
Event of Default is continuing at the time of such appointment, such
Administrative Agent shall have been approved by the Borrower), shall succeed to
the rights, powers and duties of the Administrative Agent hereunder.  Effective
upon such appointment and approval, the term "Administrative Agent" shall mean
such successor Administrative Agent, and the former Administrative Agent's
rights, powers and duties as Administrative Agent shall be terminated, without
any other or further act or deed on the part of such former Administrative Agent
or any of the parties to this Agreement or any holders of the Loans.  After any
retiring Administrative Agent's resignation as Administrative Agent, the
provisions of this Section 10 shall inure to its benefit as to any actions taken
or omitted to be taken by it while it was Administrative Agent under this
Agreement and the other Credit Documents.

                      SECTION 11.  MISCELLANEOUS

          11.1 Amendments and Waivers.  Neither this Agreement nor any other
               ----------------------
Credit Document, nor any terms hereof or thereof may be amended, supplemented or
modified except
<PAGE>

                                                                              57

in accordance with the provisions of this subsection. The Majority Lenders may,
or, with the written consent of the Majority Lenders, the Administrative Agent
may, from time to time, (a) enter into with the Borrower and/or any other
applicable Credit Party written amendments, supplements or modifications hereto
and to the other Credit Documents for the purpose of adding any provisions to
this Agreement or the other Credit Documents or changing in any manner the
rights of the Lenders or of the Borrower hereunder or thereunder or (b) waive,
on such terms and conditions as the Majority Lenders or the Administrative
Agent, as the case may be, may specify in such instrument, any of the
requirements of this Agreement or the other Credit Documents or any Default or
Event of Default and its consequences; provided, however, that no such waiver
                                       --------  -------
and no such amendment, supplement or modification shall:

          (i)   without the consent of each Lender directly affected thereby,
     reduce the amount or extend the scheduled date of maturity of any Loan or
     of any installment thereof, or reduce the stated rate of any interest or
     fee payable hereunder or extend the scheduled date of any payment thereof
     or increase the amount or extend the expiration date of any Lender's
     Commitments;

          (ii)  without the written consent of all the Lenders, amend, modify or
     waive any provision of this subsection or reduce the percentage specified
     in the definition of Majority Lenders, or consent to the assignment or
     transfer by the Borrower of any of its rights and obligations under this
     Agreement (other than any transfer to LegacyCo pursuant to the Asset
     Transfer) and the other Credit Documents, or (except to the extent provided
     in subsection 11.2) release all or substantially all of the Collateral, or
     (except to the extent provided in subsection 11.2) release any Investor
     from any material obligation relating to the Assigned Interests;

          (iii) amend, modify or waive any provision of Section 10 without the
     written consent of the then Administrative Agent; or

          (iv)  have the effect of waiving any prepayment required pursuant to
     subsection 4.5(a) on account of a Net Proceeds Event described in clause
     (b) of the definition of such term without the prior written consent of
     Investors holding a majority of the voting interests in the Capital Stock
     of Zhone (with the determination of the voting interests held by each such
     Investor being based, without independent inquiry by the Administrative
     Agent, solely upon a certification from the Borrower).

Any such waiver and any such amendment, supplement or modification shall apply
equally to each of the Lenders and shall be binding upon the Borrower, any
applicable Credit Party, the Lenders, the Administrative Agent and all future
holders of the Loans.  In the case of any waiver, the Borrower, any applicable
Credit Party, the Lenders and the Administrative Agent shall be restored to
their former positions and rights hereunder and under the other Credit
Documents, and any Default or Event of Default waived shall be deemed to be
cured and not continuing; no such waiver shall extend to any subsequent or other
Default or Event of Default or impair any right consequent thereon.

          11.2  Releases of Collateral and Credit Support.  (a)  On the Merger
          ------------------------------------------------
Date, the Premisys Escrow Agreement shall terminate without any action or
consent on the part of the Administrative Agent or any other Person and Premisys
and (after delivery of the amounts then
<PAGE>

                                                                              58

held in escrow thereunder in accordance with the terms thereof) the Escrow Agent
(as defined therein) shall be released from their respective obligations
thereunder; provided that nothing contained herein shall be deemed to cause the
termination of any provision of any such agreement which is expressly stated to
survive the termination thereof or to release any Credit Party from its
obligations under any such provision.

          (b)  On the Reorganization Date, each of the AcquisitionCo Cash
     Collateral Agreement and the Initial Collateral Agreement shall terminate
     without any action or consent on the part of the Administrative Agent or
     any other Person and the Credit Parties which are parties thereto shall be
     released from their respective obligations thereunder; provided that
     nothing contained herein shall be deemed to cause the termination of any
     provision of any such agreement which is expressly stated to survive the
     termination thereof or to release any Credit Party from its obligations
     under any such provision.

          (c)  On the date upon which Zhone consummates an initial public
     offering of its Capital Stock, the Assignment of Capital Call Rights shall
     terminate without any action or consent on the part of the Administrative
     Agent or any other Person and the Credit Parties which are parties thereto
     shall be released from their respective obligations thereunder; provided
     that no such termination and release shall occur unless:

               (i)   the Administrative Agent shall have received an amount of
          cash and Cash Equivalents which, at the date of determination, is
          equal to at least 120% of the aggregate then-outstanding principal
          amount of the Term Loans (the "Substitute Collateral");
                                         ---------------------

               (ii)  the Administrative Agent shall hold a first priority,
          perfected security interest in the Substitute Collateral, pursuant to
          the LegacyCo Cash Collateral Agreement or other documentation
          reasonably satisfactory to the Administrative Agent; and

               (iii) the Administrative Agent shall have received a satisfactory
          legal opinion from independent counsel to Zhone with respect to such
          perfection and other matters reasonably requested by the
          Administrative Agent.

Notwithstanding the foregoing, nothing contained in this subsection 11.2(c)
shall be deemed to cause the termination of any provision of the Assignment of
Capital Call Rights which is expressly stated to survive the termination thereof
or to release any Credit Party from its obligations under any such provision.

          (d)  At any time and from time to time when the fair market value of
     the Substitute Collateral exceeds 120% of the aggregate then-outstanding
     principal amount of the Term Loans, the Administrative Agent shall (upon
     written request of Zhone and the Borrower) promptly release its security
     interest in, and deliver to Zhone, a portion of the Substitute Collateral
     which is equal to such excess.

          (e)  Following the termination of any Security Document pursuant to
     the provisions of this Section 11.2 or in accordance with the terms of such
     Security
<PAGE>

                                                                              59

     Document, the Administrative Agent will (upon the request and at the
     expense of the Borrower) take such action as the Borrower reasonably shall
     request in order to evidence the termination of the Liens created pursuant
     to such Security Document and to return to the Borrower any Collateral
     which is then in the possession of the Administrative Agent.

          11.3 Notices.  All notices, requests and demands to or upon the
               -------
respective parties hereto to be effective shall be in writing (including by
facsimile transmission) and, unless otherwise expressly provided herein, shall
be deemed to have been duly given or made (a) in the case of delivery by hand,
when delivered, (b) in the case of delivery by mail, three days after being
deposited in the mails, postage prepaid, or (c) in the case of delivery by
facsimile transmission, when sent and receipt has been confirmed, addressed as
follows in the case of the Borrower and the Administrative Agent, and as set
forth in Schedule II in the case of the other parties hereto, or to such other
address as may be hereafter notified by the respective parties hereto:

          Prior to the Reorganization Date:   Zhone Acquisition Corp.

               c/o Zhone Technologies, Inc.
               7677 Oakport Street - Suite 1040
               Oakland, California  94621
               Attention:  Mory Ejabat
               Fax:  510/777-7010

          After the Reorganization Date:   Premisys Systems, LLC
               c/o Zhone Technologies, Inc.
               7677 Oakport Street - Suite 1040
               Oakland, California 94621
               Attention:  Mory Ejabat
               Fax:  510/777-7010

          The Administrative Agent:  Credit Suisse First Boston

               11 Madison Avenue
               New York, New York 10010
               Attention:  Mark Callahan
               Fax:  212/325-8304

provided that any notice, request or demand to or upon the Administrative Agent
--------
or the Lenders pursuant to subsection 2.2, 3.2, 4.3, 4.4, 4.6 or 4.11(b) shall
not be effective until received.

          11.4 No Waiver; Cumulative Remedies.  No failure to exercise and no
          -----------------------------------
delay in exercising, on the part of the Administrative Agent or any Lender, any
right, remedy, power or privilege hereunder or under the other Credit Documents
shall operate as a waiver thereof; nor shall any single or partial exercise of
any right, remedy, power or privilege hereunder preclude any other or further
exercise thereof or the exercise of any other right, remedy, power or privilege.
The rights, remedies, powers and privileges herein provided are cumulative and
not exclusive of any rights, remedies, powers and privileges provided by law.
<PAGE>

                                                                              60

          11.5  Survival of Representations and Warranties.  All representations
          ------------------------------------------------
and warranties made hereunder, in the other Credit Documents and in any
document, certificate or statement delivered pursuant hereto or in connection
herewith shall survive the execution and delivery of this Agreement and the
making of the Loans hereunder.

          11.6  Payment of Expenses and Taxes.  The Borrower agrees (a) to pay
          -----------------------------------
or reimburse the Administrative Agent for its reasonable out-of-pocket costs and
expenses incurred in connection with the development, preparation and execution
of, and any amendment, supplement or modification to, this Agreement and the
other Credit Documents and any other documents prepared in connection herewith
or therewith, and the consummation and administration of the transactions
contemplated hereby and thereby, including, without limitation, the reasonable
fees and disbursements of counsel to the Administrative Agent, (b) to pay or
reimburse each Lender and the Administrative Agent for its reasonable costs and
expenses incurred in connection with the enforcement or preservation of any
rights under this Agreement, the other Credit Documents and any such other
documents, including, without limitation, the fees and disbursements of counsel
(including the allocated fees and expenses of in-house counsel) to each Lender
and of counsel to the Administrative Agent, (c) to pay, indemnify, and hold each
Lender and the Administrative Agent harmless from, any and all recording and
filing fees and any and all liabilities with respect to, or resulting from any
delay in paying, stamp, excise and other taxes, if any, which may be payable or
determined to be payable in connection with the execution and delivery of, or
consummation or administration of any of the transactions contemplated by, or
any amendment, supplement or modification of, or any waiver or consent under or
in respect of, this Agreement, the other Credit Documents and any such other
documents and (d) to pay, indemnify, and hold each Lender and the Administrative
Agent harmless from and against any and all other liabilities, obligations,
losses, damages, penalties, actions, judgments, suits, costs, expenses or
disbursements of any kind or nature whatsoever with respect to the execution,
delivery, enforcement, performance and administration of this Agreement, the
other Credit Documents, the documentation relating to the Transaction and the
other transactions contemplated hereby, or the use of the proceeds of the Loans
and other extensions of credit hereunder and any such other documents,
including, without limitation, any of the foregoing relating to the violation
of, noncompliance with or liability under, any Environmental Law applicable to
the operations of the Borrower, any of its Subsidiaries or any of the Properties
(all the foregoing in this clause (d), collectively, the "indemnified
                                                          -----------
liabilities"), provided that the Borrower shall have no obligation hereunder to
-----------    --------
the Administrative Agent or any Lender with respect to indemnified liabilities
arising from the gross negligence or willful misconduct of the Administrative
Agent or any such Lender.  The agreements in this subsection shall survive
repayment of the Loans and all other amounts payable hereunder.

          11.7  Successors and Assigns; Participations and Assignments.  (a)
          ------------------------------------------------------------
This Agreement shall be binding upon and inure to the benefit of the Borrower,
the Lenders, the Administrative Agent and their respective successors and
assigns, except that the Borrower may not assign or transfer any of its rights
or obligations under this Agreement (other than pursuant to the Asset Transfer)
without the prior written consent of each Lender.

          (b)   Any Lender may, in the ordinary course of its commercial banking
     business and in accordance with applicable law, at any time sell to one or
     more banks or other entities ("Participants") participating interests in
                                    ------------
     any Loan owing to such Lender, any Commitment of such Lender or any other
     interest of such Lender hereunder and
<PAGE>

                                                                              61

     under the other Credit Documents. In the event of any such sale by a Lender
     of a participating interest to a Participant, such Lender's obligations
     under this Agreement to the other parties to this Agreement shall remain
     unchanged, such Lender shall remain solely responsible for the performance
     thereof, such Lender shall remain the holder of any such Loan for all
     purposes under this Agreement and the other Credit Documents, and the
     Borrower and the Administrative Agent shall continue to deal solely and
     directly with such Lender in connection with such Lender's rights and
     obligations under this Agreement and the other Credit Documents. No Lender
     shall be entitled to create in favor of any Participant, in the
     participation agreement pursuant to which such Participant's participating
     interest shall be created or otherwise, any right to vote on, consent to or
     approve any matter relating to this Agreement or any other Credit Document
     except for those specified in clause (ii) of the proviso to subsection 11.1
     or, to the extent that such Lender would have the right to vote on any
     matter specified therein, clause (i) of such proviso. The Borrower agrees
     that if amounts outstanding under this Agreement are due or unpaid, or
     shall have been declared or shall have become due and payable upon the
     occurrence of an Event of Default, each Participant shall, to the maximum
     extent permitted by applicable law, be deemed to have the right of setoff
     in respect of its participating interest in amounts owing under this
     Agreement to the same extent as if the amount of its participating interest
     were owing directly to it as a Lender under this Agreement, provided that,
                                                                 --------
     in purchasing such participating interest, such Participant shall be deemed
     to have agreed to share with the Lenders the proceeds thereof as provided
     in subsection 11.8(a) as fully as if it were a Lender hereunder. The
     Borrower also agrees that each Participant shall be entitled to the
     benefits of subsections 4.13, 4.14 and 4.15 with respect to its
     participation in the Commitments and the Loans outstanding from time to
     time as if it was a Lender; provided that, in the case of subsection 4.14,
                                 --------
     such Participant shall have complied with the requirements of said
     subsection and provided, further, that no Participant shall be entitled to
                    --------  -------
     receive any greater amount pursuant to any such subsection than the
     transferor Lender would have been entitled to receive in respect of the
     amount of the participation transferred by such transferor Lender to such
     Participant had no such transfer occurred.

          (c) Any Lender may, in the ordinary course of its commercial banking
     business and in accordance with applicable law, at any time and from time
     to time assign to (i) any Lender or any affiliate thereof or (ii) with the
     consent of the Administrative Agent and the Borrower (which, in each case,
     shall not be unreasonably withheld), to any additional bank or financial
     institution (any assignee described in clause (i) or (ii), an "Assignee")
                                                                    --------
     all or any part of its rights and obligations under this Agreement and the
     other Credit Documents pursuant to an Assignment and Acceptance,
     substantially in the form of Exhibit J, executed by such Assignee, such
     assigning Lender (and, in the case of an Assignee that is not then a Lender
     or an affiliate thereof, by the Administrative Agent and, to the extent
     required pursuant to clause (ii) above, by the Borrower) and delivered to
     the Administrative Agent for its acceptance and recording in the Register,
     provided that, in the case of any such assignment to an additional bank or
     --------
     financial institution, the sum of the aggregate principal amount of the
     Loans and the aggregate unutilized amount of the Aggregate Acquisition Loan
     Commitment being assigned and, if such assignment is of less than all of
     the rights and obligations of the assigning Lender, the sum of the
     aggregate principal amount of the Loans and the aggregate unutilized amount
     of the Aggregate Acquisition Loan Commitment remaining with the assigning
     Lender are each
<PAGE>

                                                                              62

     not less than $2,500,000 (or such lesser amount as may be agreed to by the
     Borrower and the Administrative Agent). Upon such execution, delivery,
     acceptance and recording, from and after the effective date determined
     pursuant to such Assignment and Acceptance, (x) the Assignee thereunder
     shall be a party hereto and, to the extent provided in such Assignment and
     Acceptance, have the rights and obligations of a Lender hereunder with a
     Commitment as set forth therein, and (y) the assigning Lender thereunder
     shall, to the extent provided in such Assignment and Acceptance, be
     released from its obligations under this Agreement (and, in the case of an
     Assignment and Acceptance covering all or the remaining portion of an
     assigning Lender's rights and obligations under this Agreement, such
     assigning Lender shall cease to be a party hereto). Notwithstanding any
     provision of this paragraph (c) and paragraph (e) of this subsection, the
     consent of the Borrower shall not be required, and, unless requested by the
     Assignee and/or the assigning Lender, new Notes shall not be required to be
     executed and delivered by the Borrower, for any assignment which occurs at
     any time when any of the events described in Section 9(f) shall have
     occurred and be continuing.

          d)  The Administrative Agent, on behalf of the Borrower, shall
     maintain at the address of the Administrative Agent referred to in
     subsection 11.3 a copy of each Assignment and Acceptance delivered to it
     and a register (the "Register") for the recordation of the names and
                          --------
     addresses of the Lenders and the Commitments of, and principal amounts of
     the Loans owing to, each Lender from time to time.  The entries in the
     Register shall be conclusive, in the absence of manifest or demonstrable
     error, and the Borrower, the Administrative Agent and the Lenders may (and,
     in the case of any Loan or other obligation hereunder not evidenced by a
     Note, shall) treat each Person whose name is recorded in the Register as
     the owner of a Loan or other obligation hereunder as the owner thereof for
     all purposes of this Agreement and the other Credit Documents,
     notwithstanding any notice to the contrary.  Any assignment of any Loan or
     other obligation hereunder not evidenced by a Note shall be effective only
     upon appropriate entries with respect thereto being made in the Register.

          e)   Upon its receipt of an Assignment and Acceptance executed by an
     assigning Lender and an Assignee (and, in the case of an Assignee that is
     not then a Lender or an affiliate thereof, by the Borrower and the
     Administrative Agent), together with payment to the Administrative Agent of
     a registration and processing fee of $3,500, the Administrative Agent shall
     (i) promptly accept such Assignment and Acceptance and (ii) on the
     effective date determined pursuant thereto record the information contained
     therein in the Register and give notice of such acceptance and recordation
     to the Lenders and the Borrower.

          f)   The Borrower authorizes each Lender to disclose to any
     Participant or Assignee (each, a "Transferee") and any prospective
                                       ----------
     Transferee which agrees to comply with the provisions of subsection 11.16
     any and all financial information in such Lender's possession concerning
     the Borrower and its Affiliates which has been delivered to such Lender by
     or on behalf of the Borrower pursuant to this Agreement or which has been
     delivered to such Lender by or on behalf of the Borrower in connection with
     such Lender's credit evaluation of the Borrower and its Affiliates prior to
     becoming a party to this Agreement.
<PAGE>

                                                                              63

          (g)   For avoidance of doubt, the parties to this Agreement
     acknowledge that the provisions of this subsection concerning assignments
     of Loans and Notes relate only to absolute assignments and that such
     provisions do not prohibit assignments creating security interests,
     including, without limitation, any pledge or assignment by a Lender of any
     Loan or Note to any Federal Reserve Bank in accordance with applicable law.

          (h)   Funding by Special Purpose Funding Vehicles.  Notwithstanding
                -------------------------------------------
anything to the contrary contained herein, any Lender (a "Granting Lender") may
                                                          ---------------
grant to a special purpose funding vehicle ("SPC"), identified as such in
                                             ---
writing from time to time by the Granting Lender to the Administrative Agent and
the Borrower, the option to provide to the Borrower all or any part of any Loan
that such Granting Lender otherwise would be obligated to make to the Borrower
pursuant to this Agreement, provided that (i) nothing herein shall constitute a
                            --------
commitment by any SPC to make any Loan and (ii) if an SPC elects not to exercise
such option to make a Loan or otherwise fails to provide all or any part
thereof, the Granting Lender shall be obligated to make such Loan pursuant to
the terms hereof.  The making of a Loan by an SPC hereunder shall be deemed to
constitute a utilization of the Commitment of the Granting Lender to the same
extent, and as if, such Loan were made by the Granting Lender.  Each party
hereto hereby agrees that no SPC shall be liable for any indemnity or similar
payment obligation under this Agreement (all liability for which shall remain
with the related Granting Lender).  In furtherance of the foregoing, each party
hereto hereby agrees (which agreement shall survive the termination of this
Agreement) that, prior to the date that is one year and one day after the
payment in full of all outstanding commercial paper or other senior indebtedness
of any SPC, it will not institute against, or join any other person in
instituting against, such SPC any bankruptcy, reorganization, arrangement,
insolvency or liquidation proceedings or similar proceedings under the laws of
the United States or any State thereof.  In addition, notwithstanding anything
to the contrary contained in this subsection 11.7, any SPC may (i) with notice
to, but without the prior written consent of, the Borrower or the Administrative
Agent and without paying any processing fee therefor, assign all or a portion of
its interests in any Loans to its Granting Lender or to any financial
institutions (consented to by the Borrower and the Administrative Agent)
providing liquidity and/or credit support to or for the account of such SPC to
support the funding or maintenance of Loans and (ii) disclose on a confidential
basis any non-public information relating to its Loans to any rating agency,
commercial paper dealer or provider of a surety, guarantee or credit or
liquidity enhancement to such SPC.   The provisions of this subsection 11.7(h)
may not be amended, supplemented or otherwise modified without the prior written
consent of the SPC.

          11.8  Adjustments; Set-off.  (a)  If any Lender (a "benefitted
          --------------------------                          ----------
Lender") shall at any time receive any payment of all or part of any of its
-------
Loans owing to it under any Commitment, or interest thereon, pursuant to a
guarantee or otherwise, or receive any collateral in respect thereof (whether
voluntarily or involuntarily, by set-off or otherwise), in a greater proportion
than any such payment to and collateral received by any other Lender, if any, in
respect of such other Lender's Loans owing to it under such Commitment or
interest thereon, such benefitted Lender shall purchase for cash from the other
Lender such portion of each such other Lender's similar Loans, or shall provide
such other Lender with the benefits of any such collateral, or the proceeds
thereof, as shall be necessary to cause such benefitted Lender to share the
excess payment or benefits of such collateral or proceeds ratably with each of
the Lenders which hold such Commitment; provided, however, that if all or any
                                        --------  -------
portion of such excess payment or benefits is thereafter recovered from such
benefitted Lender, such purchase shall be
<PAGE>

                                                                              64

rescinded, and the purchase price and benefits returned, to the extent of such
recovery, but without interest. The Borrower agrees that each Lender so
purchasing a portion of another Lender's Loans may exercise all rights of
payment (including, without limitation, rights of set-off) with respect to such
portion as fully as if such purchasing Lender were the direct holder of such
portion.

          (b)   In addition to any rights and remedies of the Lenders provided
by law, each Lender shall have the right, without prior notice to the Borrower,
any such notice being expressly waived by the Borrower to the extent permitted
by applicable law, upon any amount becoming due and payable by the Borrower
hereunder (whether at the stated maturity, by acceleration or otherwise) to set-
off and appropriate and apply against such amount any and all deposits (general
or special, time or demand, provisional or final), in any currency, and any
other credits, indebtedness or claims, in any currency, in each case whether
direct or indirect, absolute or contingent, matured or unmatured, at any time
held or owing by such Lender or any branch or agency thereof to or for the
credit or the account of the Borrower. Each Lender agrees promptly to notify the
Borrower and the Administrative Agent after any such set-off and application
made by such Lender, provided that the failure to give such notice shall not
                     --------
affect the validity of such set-off and application.

          11.9  Counterparts.  This Agreement may be executed by one or more of
          ------------------
the parties to this Agreement on any number of separate counterparts (including
by facsimile transmission), and all of said counterparts taken together shall be
deemed to constitute one and the same instrument.  A set of the copies of this
Agreement signed by all the parties shall be lodged with the Borrower and the
Administrative Agent.

          11.10 Severability.  Any provision of this Agreement which is
          ------------------
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction.

          11.11 Integration.  This Agreement and the other Credit Documents
          -----------------
represent the agreement of the Borrower, the Administrative Agent and the
Lenders with respect to the subject matter hereof, and there are no promises,
undertakings, representations or warranties by the Administrative Agent or any
Lender relative to subject matter hereof not expressly set forth or referred to
herein or in the other Credit Documents.

          11.12 GOVERNING LAW.  THIS AGREEMENT AND THE RIGHTS AND OBLIGATIONS
          -------------------
OF THE PARTIES HEREUNDER SHALL BE GOVERNED BY, AND CONSTRUED AND INTERPRETED IN
ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK.

          11.13 Submission To Jurisdiction; Waivers.  The Borrower hereby
                -----------------------------------
irrevocably and unconditionally:

          (a) submits for itself and its property in any legal action or
     proceeding relating to this Agreement and the other Credit Documents to
     which it is a party, or for recognition and enforcement of any judgement in
     respect thereof, to the non-exclusive
<PAGE>

                                                                              65

     general jurisdiction of the Courts of the State of New York, the courts of
     the United States of America for the Southern District of New York, and
     appellate courts from any thereof;

          (b)    consents that any such action or proceeding may be brought in
     such courts and waives any objection that it may now or hereafter have to
     the venue of any such action or proceeding in any such court or that such
     action or proceeding was brought in an inconvenient court and agrees not to
     plead or claim the same;

          (c)    agrees that service of process in any such action or proceeding
     may be effected by mailing a copy thereof by registered or certified mail
     (or any substantially similar form of mail), postage prepaid, to the
     Borrower at its address set forth in subsection 11.3 or at such other
     address of which the Administrative Agent shall have been notified pursuant
     thereto;

          (d)    agrees that nothing herein shall affect the right to effect
     service of process in any other manner permitted by law or shall limit the
     right to sue in any other jurisdiction; and

          (e)    waives, to the maximum extent not prohibited by law, any right
     it may have to claim or recover in any legal action or proceeding referred
     to in this subsection any special, exemplary, punitive or consequential
     damages.

          11.14  Acknowledgments.  The Borrower hereby acknowledges that:
          ----------------------

          (a)    it has been advised by counsel in the negotiation, execution
     and delivery of this Agreement and the other Credit Documents;

          (b)    neither the Administrative Agent nor any Lender has any
     fiduciary relationship with or duty to the Borrower arising out of or in
     connection with this Agreement or any of the other Credit Documents, and
     the relationship between Administrative Agent and Lenders, on one hand, and
     the Borrower, on the other hand, in connection herewith or therewith is
     solely that of debtor and creditor; and

          (c)    no joint venture is created hereby or by the other Credit
     Documents or otherwise exists by virtue of the transactions contemplated
     hereby among the Lenders or among the Borrower and the Lenders.

          11.15  WAIVERS OF JURY TRIAL.  THE BORROWER, THE ADMINISTRATIVE AGENT
          ----------------------------
AND THE LENDERS HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVE TRIAL BY JURY IN
ANY LEGAL ACTION OR PROCEEDING RELATING TO THIS AGREEMENT OR ANY OTHER CREDIT
DOCUMENT AND FOR ANY COUNTERCLAIM THEREIN.

          11.16  Confidentiality.  Each of the Administrative Agent and the
          ----------------------
Lenders, on behalf of itself and each of its affiliates, agents, directors,
officers and employees, agrees to keep confidential all non-public information
provided to it by any Credit Party pursuant to this Agreement that is clearly
designated by such Credit Party in writing as "confidential"; provided
<PAGE>

                                                                              66

that nothing herein shall prevent the Administrative Agent or any Lender from
disclosing any such information (a) to the Administrative Agent, any other
Lender or any affiliate, agent, director, officer or employee of any Lender, (b)
to any Transferee or prospective Transferee which agrees to comply with the
provisions of this Section, (c) any of its employees, directors, agents,
attorneys, accountants and other professional advisors, (d) upon the request or
demand of any Governmental Authority having jurisdiction over it, (e) in
response to any order of any court or other Governmental Authority or as may
otherwise be required pursuant to any Requirement of Law, (f) if requested or
required to do so in connection with any litigation or similar proceeding, (g)
which has been publicly disclosed other than in breach of this Section 11.16,
(h) to the National Association of Insurance Commissioners or any similar
organization or any nationally recognized rating agency that requires access to
information about a Lender's investment portfolio in connection with ratings
issued with respect to such Lender or (i) in connection with the exercise of any
right or remedy hereunder or under any other Credit Document.
<PAGE>

                                                                              67

          IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be duly executed and delivered by their proper and duly authorized officers as
of the day and year first above written.

                              ZHONE ACQUISITION CORP. (to be merged
                              with and into Premisys Communications, Inc. and
                              then to be succeeded by Premisys Systems, LLC)

                              By:_______________________________________________
                                 Title:

                              CREDIT SUISSE FIRST BOSTON, as
                               Administrative Agent

                              By: /s/ Robert Hetu
                                 -----------------------------------------------
                                 Title: Robert Hetu, Vice President

                              By: /s/ Vitaly G. Butenko
                                 -----------------------------------------------
                                 Title: Vitaly G. Butenko, Asst. Vice President

                              CREDIT SUISSE FIRST BOSTON, as a Term
                              Loan Lender and as an Acquisition Lender

                              By: /s/ Robert Hetu
                                 -----------------------------------------------
                                 Title: Robert Hetu, Vice President

                              By: /s/ Vitaly G. Butenko
                                 -----------------------
                                 Title: Vitaly G. Butenko, Asst. Vice President
<PAGE>

                                                                              68

          IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be duly executed and delivered by their proper and duly authorized officers as
of the day and year first above written.

                              ZHONE ACQUISITION CORP. (to be merged with and
                              into Premisys Communications, Inc. and then to be
                              succeeded by Premisys Systems, LLC)

                              By: /s/ Mory Ejabat
                                 -----------------------------------------------
                              Title:

                              CREDIT SUISSE FIRST BOSTON, as
                                Administrative Agent

                              By:_______________________________________________
                                 Title:

                              By:_______________________________________________
                                 Title:

                              CREDIT SUISSE FIRST BOSTON, as a Term Loan Lender
                              and as an Acquisition Lender

                              By:_______________________________________________
                                 Title:

                              By:_______________________________________________
                                 Title:
<PAGE>

                                                                              69

                                                                      SCHEDULE I
                                                                      ----------
                              LENDERS; COMMITMENTS

================================================================================
              Lender                   Term Loan             Acquisition Loan
                                      Commitment                Commitment
________________________________                            ____________________
Credit Suisse First Boston             $50,000,000.00             $75,000,000.00
                                                            ____________________
                                       $50,000,000.00             $75,000,000.00

===============================================================================
<PAGE>

                                                                              70

                                                                     SCHEDULE II
                                                                     -----------
                             ADDRESSES FOR NOTICES

===============================================================================
          CREDIT SUISSE FIRST BOSTON

Credit Matters:                           Administrative Matters:

    Eleven Madison Avenue                    Eleven Madison Avenue

    New York, New York 10010                 New York, New York  10010

    Attention: Robert Hetu                   Attention:

    Telephone: 212/325-4542                  Telephone:

    Facsimile: 212/325-8309                  Facsimile:

===============================================================================
<PAGE>

                                                                              71

                                                                    SCHEDULE 5.9
                                                                    ------------
                             INTELLECTUAL PROPERTY

In March of 1999, Premisys Communications, Inc. ("Premisys") received notice
from the Lemelson Medical, Education & Research Foundation Limited Partnership
("Lemelson Foundation") alleging that Premisys was infringing certain Lemelson
Foundation owned and issued United States Patents (as well as claims of certain
Lemelson Foundation owned and pending US Patent applications). Premisys and the
Lemelson Foundation have entered into discussions concerning the settlement of
the above allegations, such settlement to be in the form of a proposed license
agreement by which the Lemelson Foundation would grant to the Company fully-paid
up licenses (collectively, the "Lemelson License") with respect to the allegedly
infringed-upon patents. The currently proposed, fully-paid up, aggregate license
fee for the Lemelson License is approximately $47,500, calculated according to
the following formula: a royalty rate of 0.00005, multiplied by the sum of the
US component of both (i) the Company's actual Company-wide revenues for the past
five years and (ii) the Company's projected revenues over the next five years.
The proposed license agreement, a draft of which has been made available to
Zhone Technologies, Inc., has not yet been executed; however, the substantive
terms of the proposed license agreement have been agreed to "in principle" by
the parties. As currently drafted, the proposed license agreement is assignable
provided notice is given to the Lemelson Foundation. The Company does not know
how this "agreement in principle," if not executed in writing prior to the
execution of this Agreement, might be affected by the proposed acquisition,
including whether the "agreement in principle" would be rescinded or whether the
royalty amount would be recalculated.
<PAGE>

                                                                              72

                                                                    SCHEDULE 8.2
                                                                    ------------
                             EXISTING INDEBTEDNESS

The following equipment financing leases with respect to Premisys
Communications, Inc. provided by Premisys Communications, Inc.:

<TABLE>
<CAPTION>
===========================================================================================================================
       Company                           Equipment Leased          Lease Start       Lease End Date       Monthly
                                                                      Date                                Payment
<S>                                 <C>                            <C>               <C>                 <C>
AT&T Credit Corporation              Lucent Definity GS8 PBX         April 1998          March 2001      $1,014.88

AT&T Credit Corporation              PBX voice mail capacity         July 1998           June 2001       $1,144.96

AT&T Credit Corporation                Definity PBX add-on           June 1998           May 2001        $  116.09

AT&T Credit Corporation                Definity PBX add-on           June 1998           May 2001        $  638.42

AT&T Credit Corporation             T-1 cards for PacBell trunk      May 1999            August 2001     $1,168.53

AT&T Credit Corporation                Definity PBX add-on           July 19999          August 2001     $  269.94

Eastman Kodak Credit Corp.             Kodak Ektaprint copies        September 1996      August 2000     $  388.00

Lucent Technologies Product             Phone system add-on          May 1999            December 2003   $   80.15
  Finance

===========================================================================================================================
</TABLE>
<PAGE>

                                                                              73

                                                                    SCHEDULE 8.3
                                                                    ------------
                                EXISTING LIENS

None, other than those disclosed by Premisys Communications, Inc. with respect
to liens on the equipment described in Schedule 8.2 securing the related finance
leases.
<PAGE>

                                                                              74

                                                                    SCHEDULE 8.4
                                                                    ------------
                              EXISTING GUARANTEES

Premisys Communications, Inc. guarantees the debt and other obligations of its
overseas subsidiaries Premisys Communications (Canada) Inc. and Premisys
Communications Ltd. (U.K.).
<PAGE>

                                                                              75

                                                                   SCHEDULE 8.17
                                                                   -------------
                     SUBSIDIARIES OF PREMISYS SYSTEMS, LLC

===============================================================================
Name of Subsidiary                                    Interest Owned
                                                  by

                                                      Premisys
                                                  Systems, LLC

Premisys Communications (Canada), Inc.*               100%

Premisys Communications Ltd. (U.K.)                   100%

Premisys Communications Pte. Ltd. (Singapore)         approx. 100%

===============================================================================
* Prior to the Reorganization Date, the Borrower may elect to structure the
Asset Transfer in a manner which causes Premisys Communications (Canada), Inc.
not to be a Subsidiary of Premisys Systems, LLC, in which event Premisys
Communications (Canada), Inc. shall be deemed to be deleted from this Schedule
8.17.

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00016-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00016-of-00352.parquet"}]]