Document:

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                                                                   EXHIBIT 10.10

COMMERCIAL LEASE AGREEMENT

THIS AGREEMENT OF LEASE (the "Lease") is entered into between EAST COLLINS,
L.P., a Texas limited partnership, as Landlord, and CHORUM TECHNOLOGIES, INC., a
Delaware corporation, as Tenant, in consideration of the terms, provisions and
covenants provided hereinafter, to be effective the 10th day of October, 2000.

Article I: Basic Provisions

1.01. Landlord. East Collins, L.P., a Texas limited partnership, located at c/o
Devcor Equities, Inc., 100 Alexis Nihon Blvd., Suite 290, St. Laurent, Quebec,
Canada H4M 2N7.

1.02. Tenant. Chorum Technologies, Inc., a Delaware corporation, located at 1089
E. Collins Blvd., Richardson, Texas  75081.

1.03. Premises. The demised premises of the Lease shall include a single
building, known as 1089 East Collins (the "Building"), consisting of
approximately 64,155 square feet of space, and located at 1089 E. Collins Blvd.,
Richardson, Texas 75081, and that certain tract of land more particularly
described on Exhibit A hereto (the "Land"), on which the Building is situated,
together with all other existing improvements located on the Land. The Building,
the Land and all improvements thereto are referred to hereinafter together as
the "Premises," as is reflected on Exhibit B hereto.

1.04. Base Rent. The Base Rent for the primary term of the Lease shall be
$4,041,765.00, to be paid in monthly installments of $48,116.25 ("Rent"), as
provided hereinafter in Section 3.02, plus an additional pro rata amount for a
partial month if the Rental Commencement Date should commence on any day other
than the first day of a month.

1.05. Lease Term. The primary term of the Lease shall commence with the
execution and delivery of the Lease by both Landlord and Tenant, at which time
Tenant will be given immediate access to the Premises to commence its
improvements to the Premises and all obligations of the parties under the Lease
shall commence, except for the payment of monthly Rent, as provided hereinafter,
and. shall expire seven (7) years from the first day of the first month
following the Rental Commencement Date, as provided hereinafter; provided
however that, if such Rental Commencement Date is the first day of a month, such
term shall continue thereafter to and including the date which is seven (7)
years from such Rental Commencement Date.

1.06. Rental Commencement Date. The earliest of (a) January 1, 2001, (b) ninety
(90) days after the effective date of this Lease, or (c) thirty (30) days after
(i) the Phase I assessment (Section 13.05 herein) is completed reflecting no
environmental deficiencies requiring remediation or (ii) the satisfactory
completion of remediation work arising from the Phase I assessment. The first
month's Rent ($48,116.25) to be paid by Tenant to Landlord with Tenant's
execution and delivery of the Lease to Landlord for execution by Landlord.
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1.07. Security Deposit. $48,116.25, to be paid by Tenant to Landlord in addition
to the first month's Rent with Tenant's execution and delivery of the Lease to
Landlord for execution by Landlord.

1.08. Reimbursed Expenses. To the extent set forth in Article VII hereof, Tenant
to reimburse Landlord for all costs incurred by Landlord relating to the
management, maintenance, repair and operation of the Premises, as well as all
costs of insurance required to be maintained by Landlord hereunder.

1.09. Taxes. All ad valorem taxes on the Premises incurred by Landlord to be
reimbursed by Tenant. Tenant to pay all taxes on Tenant's property.

1.10. Utilities. All utilities servicing the Premises to be paid by Tenant.

1.11. Landlord Improvements/Allowance. Landlord to re-stripe parking lot, paint
exterior of Building and provide a monetary allowance to Tenant, as provided
more specifically hereinafter, for Tenant's improvements to the Premises.

1.12. Permitted Use. General office, light manufacturing, warehousing and
distribution of various products (not including foodstuffs, cosmetics or
chemical-related products) which do not generate undesirable or excessive noise,
traffic, odors or other nuisances.

Article II: Grant of Premises and Term

2.01. Lease Grant. In consideration of the mutual obligations and covenants
herein, Landlord hereby leases the Premises to Tenant and Tenant leases the
Premises from Landlord, subject to the terms, conditions and provisions herein.

2.02. Term. The term of this Lease shall be for a period commencing on the
effective date of this Lease and expiring approximately seven (7) years after
the Rental Commencement Date, as is more specifically set forth in Sections 1.05
and 1.06 herein.

2.03. Holding Over. Tenant shall vacate and deliver possession of the Premises
to Landlord in good, clean condition, ordinary wear and tear excepted, and with
all hazardous materials and other adverse environmental conditions, caused by
Tenant, its agents, contractors, employees and invitees, abated in accordance
with applicable law, on or before the expiration date of the Lease. Absent
written agreement by Landlord to the contrary, if Tenant should fail to vacate
the Premises of the Lease on or before the expiration date, Tenant's occupancy
shall be on a day-to-day basis and the Rent due during the holdover period shall
be on a per diem basis at a rate equal to one hundred fifty percent (150%) of
the Rent due for the last full month of the primary term of the Lease. In the
event that Tenant should hold over beyond the expiration date, Landlord shall
have the right to commence legal eviction proceedings after three (3) days prior
written notice to Tenant and to recover all attorney's fees and costs incurred
by Landlord as a result of any such proceedings.
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2.04. Option to Renew. Landlord hereby grants to Tenant one (1) option to renew
the Lease for an additional five (5) years at a rental rate to be determined by
multiplying the initial rental rate of $9.00 per square feet by a fraction, the
numerator of which shall be the Consumer Price Index for the Dallas-Fort Worth
metropolitan area promulgated by the United States Department of Labor (the
"CPI") for September, 2007, and the denominator of which shall be the CPI for
September, 2000. However, under no circumstances shall the rental rate for the
renewal term be less than the rental rate for the last month of the primary term
of the Lease. If Tenant should exercise this option to renew, all other
obligations, conditions and provisions of the Lease shall continue as provided
herein or as may be amended by subsequent written agreement of Landlord and
Tenant. In order to exercise this option to renew, Tenant must deliver to
Landlord written notice of Tenant's exercise of the option, which must be
actually received by Landlord at least one hundred eighty (180) days prior to
the expiration of the primary term of the Lease.

Article III: Rent and Security Deposit

3.01. Initial Rent Payment. With the execution and delivery of this Lease by
Tenant to Landlord, Tenant shall pay to Landlord the sum of $48,116.25 as
payment of the first (lst) month of the Lease.

3.02. Monthly Rent. Beginning with the second (2nd) month of the Lease, and
continuing thereafter each month through the last month of the Lease, Tenant
shall pay to Landlord monthly Rent in the amount of $48,116.25 on or before the
first (lst) day of each month.

3.03. Manner of Payment. All payments of Rent shall be made payable to Landlord
("East Collins, L.P. ") and delivered to Landlord's managing agent, Columbine
United Cos., at 6757 Arapaho Road, Suite 711, LB 386, Dallas, Texas 75248, or to
such other person, entity or address which Landlord may direct by written notice
to Tenant.

3.04. Good Funds. If, for whatever reason whatsoever, any two (2) or more
payments for Rent by check from Tenant should be dishonored by Tenant's bank and
returned unpaid, Landlord may for a period of twelve (12) months thereafter
require Tenant to make payments of Rent with good funds, i.e., by cash,
certified check, cashier's check or money order, in which event during such
twelve (12) month period the delivery of Tenant's company check will no longer
constitute the payment of Rent due and any such payment, not by good funds, may
be rejected by Landlord. Any acceptance by Landlord of a payment of Rent by
Tenant's company check during such twelve (12) month period shall not be
construed as a waiver of Landlord's right to require the payment of Rent with
good funds.

3.05. Security Deposit. With the execution and delivery of this Lease by Tenant
to Landlord, Tenant shall pay to Landlord the additional sum of $48,116.25 to be
credited by Landlord as a security deposit for the balance of the term of the
Lease, which deposit shall be available to Landlord, if Landlord chooses to do
so, after the notice and cure periods provided in Article X herein, to cure any
monetary defaults of Tenant under the Lease and to reimburse Landlord for any
physical damages to the Premises beyond ordinary wear and tear at the expiration
or early termination of the Lease. If Landlord should elect to use any portion
of the security deposit, Tenant shall replenish the security deposit in like
amount within ten (10) days of receipt of
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written demand from Landlord. No interest shall accrue or be paid on the
security deposit, and Landlord shall have: no obligation to segregate the
security deposit from other Landlord funds or accounts. Upon the expiration or
any early termination of the Lease, not resulting from Tenant's default, and
after Tenant has vacated the Premises in good, clean condition, Landlord shall
refund to Tenant the unused portion of the security deposit within thirty (30)
days after the expiration or termination date or thirty (30) days after receipt
of written notice from Tenant as to what address to send the security deposit,
whichever is later.

Article IV: Condition of Premises and Initial Improvements

4.01. Condition of Premises. Tenant agrees to take the Premises of the Lease in
"as is" condition, subject only to the initial improvements to be provided by
Landlord as set forth hereinafter, punch list items relating to such
improvements and any latent defects.

4.02. Environmental. Landlord agrees to provide to Tenant the most recent report
in Landlord's possession addressing the environmental condition of the Premises,
and Tenant shall have no responsibility to remediate any pre-existing adverse
environmental conditions of the Premises. As provided hereinafter in Article
XHI, Tenant shall be responsible for any adverse environmental conditions which
may develop during the term of the Lease arising out of Tenant's occupancy and
use of the Premises.

4.03. Landlord Improvements. Landlord shall, at Landlord's sole expense, (i) re-
stripe the parking lot of the Premises and (ii) paint the exterior of the
Building with a color to be reasonably approved by Tenant. Upon the final
execution and delivery of the Lease by both Landlord and Tenant, Landlord shall
proceed to contract for the foregoing improvements and commence said work as
soon as is reasonably possible.

4.04. Landlord Allowance .Landlord shall provide to Tenant a monetary allowance
in the amount of $442,000.00 as Landlord's contribution to Tenant's improvements
to the Premises, which allowance shall be paid to Tenant upon the substantial
completion of Tenant's improvements to and occupancy of the Premises, except as
otherwise provided in Section 13.05 herein.

4.05. Tenant Improvements. Other than the improvements by Landlord set forth in
Section 4.03 herein, Tenant at its sole expense shall be responsible for the
installation of a new roof and HVAC system (not less than 300 tons) to the
Building, pursuant to such plans and specifications to be approved in advance by
Landlord, consent not to be unreasonably withheld or delayed, and such other
initial improvements to the Premises, both interior and exterior, as Tenant
considers appropriate, but subject to Landlord's approval as provided
hereinafter. In that regard, prior to the commencement of any improvements by
Tenant, Tenant shall, as may be necessary or desirable, engage space planners,
design engineers and/or architects of its choosing to provide all architectural,
engineering, mechanical and space planning plans and specifications for
Landlord's review and reasonable approval. Tenant shall have the right to engage
a general contractor and/or project manager, to be approved by Landlord, which
approval shall not be unreasonably withheld or delayed, to supervise and
coordinate the construction and installation of Tenant's improvements. Any
contractor or project manager shall provide to Landlord proof of appropriate
insurance and bonding to protect the interests of Landlord in The Premises.
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4.06. Warranties. To the extent permitted by the terms thereof, all warranties
relating to the installation of the roof, the HVAC system and any other Tenant
improvements, which are permanently attached to the Premises, shall be issued in
favor of both Landlord and Tenant.

4.07. Coordination. In order to minimize expense and to maximize efficiency,
Landlord and Tenant agree to cooperate and coordinate with each other with
regard to the improvements to be done by Landlord and Tenant on a
contemporaneous basis.

4.08. Inspection. Landlord shall have the right from time to time to inspect the
Premises upon twenty-four (24) hours notice, verbal or written, to Tenant.

Article V: Taxes

5.01. Reimbursement by Tenant. Tenant shall reimburse Landlord for all ad
valorem taxes incurred by Landlord, as is more specifically provided in Section
7.04 herein.

5.02. Tenant's Property. Tenant shall be responsible for the payment of all
taxes assessed against Tenant's trade fixtures, furniture, equipment and other
personal property in or upon the Premises.

5.03. Appraisal Protests. Landlord shall provide to Tenant all notices of
appraisal of the Premises from the various taxing authorities. Both Landlord and
Tenant shall have the right to protest any such notice of appraisal, as provided
by Texas law. Regardless of whether Landlord or Tenant should initiate a
protest, Tenant shall be responsible for the costs of prosecuting a protest and
shall reimburse Landlord for all costs incurred by Landlord in pursuit of a
protest. In the event that Landlord wishes to file a protest, Landlord shall so
advise Tenant. If Tenant disagrees with Landlord's intent to protest, Tenant
shall so advise Landlord, in which case, if Landlord proceeds with a protest,
the cost of the protest shall be at Landlord's sole expense.

5.04. Tax Abatements. In the event that Tenant, because of public policy,
contractual agreement with any taxing jurisdiction, or law, is exempt from
payment of taxes or any portion thereof, or is entitled to an abatement or
reduction of taxes as a result thereof, and such exemption, abatement, or
reduction results in an exemption, abatement, or reduction of taxes for the
Premises, then to the full extent of such exemption, abatement or reduction, the
amounts paid by Tenant for taxes shall be equally reduced. In the event the
Premises qualifies for other enhancement benefits from any taxing jurisdiction,
or any municipal, county, state or federal instrumentality, governmental or
quasi-governmental agency, department or authority on account of Tenant's
execution of this Lease, construction of improvements in the Premises, or
additional jobs resulting from Tenant's operations in the Demised Premises, then
such enhancement benefits shall inure to the sole benefit of Tenant, except to
the extent of taxes assessed against the Premises, as provided hereinafter.
Landlord shall cooperate with Tenant in Tenant's efforts to qualify for, and
receive, any such tax exemptions, tax abatements, tax reductions and enhancement
benefits. Notwithstanding any tax. concessions or benefits accruing to Tenant as
a result of its use and occupancy of the Premises, Tenant shall reimburse
Landlord for all taxes assessed against the Premises during the term of the
Lease or any extensions thereof.
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Article VI: Insurance

6.01. Tenant's Cost. Tenant shall pay the costs of all policies of insurance
relating to Tenant and to the Premises, which are issued at the instance of
Tenant. Furthermore, Tenant shall reimburse Landlord for all policies of
insurance required to be maintained by Landlord hereunder, as is more
specifically provided in Section 7.05 herein.

6.02. Landlord Casualty Coverage. During the term of the Lease and any extension
thereof, Landlord shall maintain such policies of insurance covering loss of or
damage to the Premises in an amount sufficient to cover one hundred percent 100
% of the reasonable replacement value of the Premises, including all
improvements to the Premises made by Landlord and Tenant. The policies shall
provide protection against all perils included within the classification of fire
and extended coverage and any other perils which Landlord deems necessary and
appropriate.

6.03. Tenant Casualty Coverage. During the term of the Lease and any extension
thereof, Tenant shall maintain such policies of insurance covering loss of or
damage to Tenant's fixtures, furniture, equipment and any other personal
property within or upon the Premises to cover eighty percent (80 %) of the
reasonable replacement value of same.

6.04. Liability Coverage. Throughout the term of the Lease and any extensions
thereof, Tenant shall maintain a commercial general liability policy of
insurance, at Tenant's expense, naming Landlord as an additional insured and
insuring against liability arising out of the ownership, use, occupancy and
maintenance of the Premises, with minimum amounts of coverage of (i) $2,000,000
for each occurrence, (ii) $5,000,000 general aggregate for each policy year,
(iii) $100,000 medical expense, and (iv) $5,000,000 general commercial liability
umbrella. The policy/policies must contain language which prohibits cancellation
or modification except upon thirty (30) days prior written notice to Landlord.
Tenant shall deliver a copy of the policy/policies or certificates of insurance
as to same prior to the commencement date of the Lease. The insurance coverage
obtained by Tenant shall not limit Tenant's liability nor relieve Tenant of any
obligations under this Lease and must be applicable to Tenant's indemnity
hereinafter in Section 6.05.

6.05. Tenant's Indemnity. Tenant hereby indemnifies and holds Landlord harmless
from any and all claims, causes of action, losses and damages, including defense
costs by counsel of Landlord's choosing, arising during the term of the Lease
and any extensions thereof out of (i) the acts and omissions of Tenant and
Tenant's employees, agents, representatives, contractors and invitees, and (ii)
Tenant's occupancy and use of the Premises. Tenant shall not be liable to
Landlord for any intentional misconduct or negligent acts or omissions of
Landlord of Landlord's employees, agents, representatives and invitees.

6.06. Landlord's Indemnity. Landlord hereby indemnifies and holds Tenant
harmless from any and all claims, causes of action, losses and damages,
including defense costs by counsel of Tenant's choosing, arising during the term
of the Lease and any extensions thereof out of (i) the acts and omissions of
Landlord and Landlord's employees, agents, representatives and invitees and (ii)
the performance of Landlord's obligations under the Lease, except that Landlord
shall
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not be liable to Tenant for any intentional misconduct or negligent acts or
omissions of Tenant or Tenant's employees, agents, representatives and invitees.

6.07. Waiver of Subrogation. Each party to this Lease hereby waives each and
every claim, which may arise in its favor against the other party during the
term of this Lease or any extension thereof, for any and all loss of, or damage
to, any of its property located within or upon, or constituting a part of the
Premises, which loss or damage is covered by and recoverable under valid fire
and extended coverage insurance policies, or would be covered under the
insurance policies required to be maintained. hereunder. Each party hereby
agrees to provide notice of this mutual waiver of subrogation to each insurance
company providing fire or extended coverage insurance to either party and to
cause such policies to be properly endorsed to prevent the invalidation of
coverage by reason of these mutual waivers.

Article VII: Management of Premises, Operating Costs and Utilities

7.01. Landlord's Manager. Landlord shall engage the services of a management
company to serve as Landlord's managing agent to collect the Rent and any other
monetary obligations, to pay all taxes assessed against the Premises, to inspect
the Premises from time to time, to oversee and provide all repair and
maintenance services to the exterior facilities of the Premises (which services
shall be the responsibility of Landlord with a right of reimbursement as
provided hereinafter), and to be available to act on behalf of Landlord with
regard to Landlord's obligations hereunder, for which services Landlord shall
incur a management fee to its managing agent in an amount not to exceed four
percent (4%) of all sums collected from Tenant hereunder, not including any
payments collected pursuant to any Tenant indemnity hereunder or any insurance
proceeds, which fee shall be reimbursed to Landlord by Tenant as provided
hereinafter. All costs incurred by Landlord with regard to the foregoing
services shall be reimbursed to Landlord as provided hereinafter.

7.02. Tenant Maintenance. Except as otherwise provided herein, Tenant shall be
responsible for the overall repair and maintenance of all aspects of the
interior of the Building at Tenant's sole cost and expense. Tenant shall not be
responsible for the initial improvements to the Premises by Landlord, as
provided in Section 4.03 herein, for any matters relating to the structural
integrity of the Building, or any capital replacement costs to the roof, the
parking lot and the exterior utility lines servicing the Building, which items
shall be performed by and paid for at the sole expense of Landlord.

7.03. Utilities. Except as otherwise provided in this Lease, Tenant shall be
responsible for all utility services and pay directly to each utility provider
all costs related to the installation, repair and cost of service, as well as
any deposits required by each utility provider. Notwithstanding Tenant's
responsibility for utilities, Tenant shall notify the Landlord as to all
installation of, modifications and repairs to utility services and obtain the
Landlord's approval of any such installations, modifications or repairs, for
which Tenant is responsible, prior to same being done, which approval or consent
shall not be unreasonably withheld. No prior notice shall be required for
emergency repairs.
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7.04. HVAC Replacement. In the event that during the term of the Lease, or any
extension thereof, the HVAC system or any capital component of same shall fail,
and it should become necessary to replace said system or component, Landlord
shall arrange for all necessary replacement work and shall pay for the costs of
any such replacement cost, and Tenant shall reimburse Landlord for a portion of
the replacement cost of the HVAC system or any capital component of same, to be
determined by multiplying the costs of replacement times a fraction, the
numerator of which shall be the number of years remaining in the term of the
Lease, and the denominator of which shall be the projected life of the
replacement HVAC system. In the event that HVAC replacement costs are incurred
prior to the end of the primary term of the Lease and Tenant should thereafter
extend the term of the Lease, at the commencement of such extension term Tenant
shall reimburse Landlord in an amount equal to the replacement cost multiplied
by a fraction, the numerator of which is five (5) and the denominator of which
shall be the number of years comprising the original projected life of the
replacement HVAC system or capital component of same.

7.05. Reimbursement by Tenant. Commencing with the effective date of this Lease,
Tenant shall reimburse Landlord for all taxes assessed against the Premises, all
policies of insurance required to be maintained by Landlord hereunder, operating
costs and management fees incurred by Landlord. Such reimbursement shall be
accomplished by Tenant by making an estimated payment to Landlord on or before
the first (1st) day of each month, in addition to the monthly Rent due for the
month. The amount of the monthly estimate shall be equal to one-twelfth (1/12)
of the projected costs to be, incurred by Landlord for taxes, insurance,
operating costs and management fees for the calendar year (the "Costs"). In that
regard, Landlord represents that the actual Costs for 1999 were $2.18 per square
foot. The Costs shall not include legal fees incurred by Landlord, costs to
remediate Hazardous Materials (as provided hereafter) which are Landlord's
responsibility herein, and any other capital expenditure for which Landlord is
solely responsible herein. At the beginning of each new calendar year, Landlord
shall have the right to adjust the monthly estimate for the new year, based on
Landlord's good faith estimate of the Costs to be incurred for the new year. At
the end of each calendar year Landlord shall conduct a year-end reconciliation
of the actual Costs incurred for the prior year (or partial year on a pro rata
basis) and compare the actual Costs to the estimated monthly payments made by
Tenant during the prior calendar year and deliver to Tenant a written report of
the results of said reconciliation as soon as reasonably possible. To the extent
that Landlord's actual annual Costs exceed the estimated payments made by Tenant
for the prior calendar year, Tenant shall pay to Landlord, the amount underpaid
within thirty (30) days of written notice from Landlord. To the extent that the
actual Costs for the prior calendar year are less than the estimated payments
made by Tenant, the overpayment shall be credited against Tenant's estimated
monthly payments for the new calendar year. Tenant shall have the right to
conduct an annual audit, at Tenant's expense, of Landlord's books and records
relating to the calculation of Tenant's reimbursement obligations
aforementioned.

Article VIII: Use of Premises

8.01. Permitted Use. Tenant shall be permitted to use the Premises for general
office, light manufacturing, warehousing and distribution of various products
(not including foodstuffs,
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cosmetics or chemical-related products), which do not
generate undesirable or excessive noise, traffic, odors or other nuisances.

8.02. Compliance with Laws/Nuisance. Tenant shall use the Premises and conduct
its business activities in full compliance with all laws, regulations and
ordinances (federal, state and municipal), and not allow any nuisance to develop
or exist as a result of Tenant's use of the Premises.

8.03. Alterations. Tenant shall be permitted to make reasonable alterations to
the Premises at Tenant's sole expense to accommodate the needs and purposes of
Tenant's business, as long as any such alterations do not impact the structural
integrity of the Premises. Prior to making any alterations to the exterior of
the Premises or to the electrical, mechanical or plumbing systems servicing the
Premises, Tenant shall provide Landlord with notice of the proposed alterations,
with plans and specifications when necessary and appropriate to inform Landlord
fairly as to the proposed alterations, for review, approval and written consent
by Landlord, which consent shall not be unreasonably withheld. No consent shall
be required for non-structural, interior alterations which do not affect the
systems hereinabove mentioned. Tenant hereby agrees to reimburse, indemnify and
hold Landlord harmless from any and all damages, losses and claims, including
defense costs by counsel of Landlord's own choosing, incurred by Landlord as a
result of Tenant's alterations to the Premises in violation of the provisions of
this Section 8.03.

8.04. No Liens. Tenant shall allow no liens of any kind to be imposed on the
Premises as a result of the acts or omissions of Tenant or its employees, agents
or contractors.

8.05. Signage. Tenant shall have the right to install its name and/or corporate
logo on the facade of the Building and/or in the form of a monument sign located
on the exterior grounds of the Premises, subject to Landlord's inspection in
advance of installation and approval as to size and format, which approval shall
not be unreasonably withheld. All costs related to the manufacture and
installation of any sign or monument shall be at Tenant's expense. Upon the
expiration or early termination of the Lease, Tenant shall remove all signs and
monuments (unless Landlord elects to keep the base monument sign) and repair the
facade of the Building and/or the grounds of the Premises to return the facade
and/or the grounds to the condition which existed prior to installation.

8.06. Condition of Premises. Tenant shall use the Premises and conduct its
business activities in a manner which keeps the Premises in good, clean
condition and avoids damage to the Premises beyond ordinary wear and tear. At
the expiration or early termination of the Lease, Tenant shall deliver the
Premises in good, clean condition, except for ordinary wear and tear, and with
any hazardous materials or other adverse environmental conditions arising out of
Tenant's use and occupancy of the Premises abated in accordance with applicable
law, ordinance or regulation.

Article IX: Assignment and Subletting

9.01. Proposal. In the event that Tenant should wish to assign this Lease or
sublease all or a portion of the Premises during the term of the Lease or any
extension thereof, Tenant shall submit a written proposal to Landlord outlining
the identity of the proposed assignee or
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sublessee, the intended use of the Premises by the proposed assignee or
sublessee, and the terms of the proposed assignment or sublease, as well as
submitting current financial statements as to the proposed assignee or sublessee
sufficient for Landlord to evaluate the financial strength of the proposed
assignee or sublessee and the suitability of the proposed assignee or sublessee
as a tenant for the Premises.

9.02.  Landlord's Consent. Landlord shall respond in writing to Tenant's
proposal for assignment or sublease within fifteen (15) days of receipt of
Tenant's complete written proposal, consent not to be unreasonably withheld.
Failure of the Landlord to respond in writing within fifteen (15) days shall be
deemed approval of Tenant's proposed assignment or sublease. If Tenant's
proposal is consented to by Landlord, a written Assignment of Lease or Sublease
shall be executed by Tenant and by the proposed assignee or sublessee and
consented to in writing by Landlord. With the execution of the Assignment of
Lease or Sublease, Tenant shall reimburse Landlord for all reasonable attorney's
fees and costs incurred with regard to the proposed assignment or sublease, not
to exceed $2,500.00, unless litigation should ensue as a result of the proposed
assignment or sublease.

9.03.  Affiliates. It shall not be necessary for Tenant to obtain the approval
or consent to assign or sublease the Premises to an affiliated entity, which
shall mean any entity which (a) directly or indirectly controls Tenant, (b) is
controlled by or is under common control with Tenant, (c) is a successor entity
related to Tenant by merger, consolidation or reorganization, or (d) is a
purchaser of all or substantially all of Tenant's assets and liabilities, and
whose use of the Premises is not inconsistent with the requisites of this Lease.

9.04.  Continuing Liability. In the event of an assignment or sublease, Tenant
shall remain liable to Landlord on a primary, joint and several, basis for all
obligations of the tenant of the Lease for the balance of the term of the Lease.

9.05. Sublease Rent. In the event that Landlord should consent to a sublease of
all or a portion of the Premises, Tenant shall remain obligated for the full
amount of the Rent herein, however, in the event that the terms of the sublease
provide for a rental rate in excess of Tenant's rate of Rent herein, Tenant and
Landlord shall share equally the increase of rental under the sublease. With
regard to the payment of rent by any subtenant, Landlord shall have the right to
direct whether the subtenant shall pay its rent directly to Landlord or to
Tenant .

Article X: Default and Remedies

10.01. By Tenant. Each of the following events shall constitute an "Event of
Default"

(a) Failure to pay Rent or any other monetary obligation within ten (10) days of
written notice from Landlord of non-receipt of payment, except that Landlord
shall not be obligated to give written notice of non-receipt of payment more
than three (3) times in any calendar year; or

(b) Failure to perform any other obligation or covenant under the Lease and the
continuation of that failure for a period of thirty (30) days after delivery of
written notice from Landlord to Tenant to correct the failure to perform,
provided that if such failure cannot be cured within such
<PAGE>

thirty (30) day period, Tenant shall have such additional time as necessary to
cure such default if Tenant commences curative action within such thirty (30)
day period and thereafter diligently pursues such cure to completion; or

(c) The commencement of voluntary bankruptcy proceedings by Tenant, or if Tenant
should undertake to make a general assignment for the benefit of creditors; or

(d) The imposition of a lien on the Premises, caused by the acts or omissions of
Tenant, its agents or employees, and which Tenant has not caused to be released
or bonded around within thirty (30) days of written demand from Landlord.

10.02. Remedies Against Tenant. Upon the occurrence of an Event of Default by
Tenant in Section 10.01 herein, Landlord shall have the right to exercise any
one (1) or more of the following remedies:

(a) Terminate this Lease, in which event Tenant shall immediately surrender the
Premises to Landlord. If Tenant fails to so surrender the Premises, Landlord
may, without prejudice to any other remedy which it may have for possession of
the Premises or Rent in arrears, enter upon and take possession of the Premises
and expel or remove Tenant and any other person who may be occupying the
Premises or any part thereof, without being liable for prosecution or any claim
for damages, except for any claims caused by the gross negligence or willful
misconduct of Landlord. Tenant shall pay to Landlord on demand the amount of all
loss and damage which Landlord may suffer by reason of the termination, whether
through inability to re-let the Premises on satisfactory terms or otherwise.

(b) Enter upon and take possession of the Premises without terminating this
Lease and without being liable for prosecution or for any claim for damages,
except for any claims caused by the gross negligence or willful misconduct of
Landlord, and expel or remove Tenant and any other person who may be occupying
the Premises or any part thereof. Landlord may re-let the Premises and receive
the rent therefor. Tenant agrees to pay to Landlord monthly or on demand from
time to time any deficiency that may arise by reason of any such re-letting. In
determining the amount of the deficiency, the professional service fees,
attorney's fees, court costs, remodeling expenses and other costs of re-letting
shall be subtracted from the amount of rent received under the re-letting.

(c) Enter upon the Premises without terminating this Lease and without being
liable for prosecution or for any claim for damages, except for any claims
caused by the gross negligence or willful misconduct of Landlord, and do
whatever Tenant is obligated to do under the terms of this Lease. Tenant agrees
to pay Landlord on demand for expenses which Landlord may incur in thus
effecting compliance with Tenant's obligations under this Lease, together with
interest thereon at the rate of twelve percent (12%) per annum from the date
expended until paid. Landlord shall not be liable for any damages resulting to
Tenant from such action, whether caused by negligence of Landlord or otherwise,
except for any claims caused by the gross negligence or willful misconduct of
Landlord.
<PAGE>

(d) Accelerate and declare the Rent for the entire term of the Lease, and all
other amounts due under this Lease, at once due and payable, such sums to be
discounted to present value at the rate of eight percent (8%) per annum and
reduced by the fair rental value of the Premises for the balance of the term of
the Lease (also discounted to present value at the rate of eight percent [8 %]
per annum), and proceed by attachment, suit or otherwise, to collect all amounts
in the same manner as if all such amounts due; or to become due during the
entire term of the Lease were payable in advance by the terms of this Lease, and
neither the enforcement or collection by Landlord of such amounts nor the
payment by Tenant of such amounts shall constitute a waiver by Landlord of any
breach, existing or in the future, of any of the terms or provisions of this
Lease by Tenant or a waiver of any rights or remedies which the Landlord may
have with respect to any such breach.

(e) In addition to the foregoing remedies, Landlord shall have the right to
change or modify the locks to the Building in the event that there is an Event
of Default for nonpayment of Rent. Landlord shall not be obligated to provide
another key to Tenant or allow Tenant to regain entry to the Premises unless and
until Tenant pays Landlord all Rent which is delinquent. Tenant agrees that
Landlord shall not be liable for any damages resulting to the Tenant from the
lockout, except for any claims caused by the gross negligence or willful
misconduct of Landlord.

(f) No re-entry or taking possession of the Premises by Landlord shall be
construed as an election to terminate this Lease, unless a written notice of
that intention is given to Tenant. Notwithstanding any such re-letting or re-
entry or taking possession, Landlord may, at any time thereafter, elect to
terminate this Lease for a previous Event of Default. Pursuit of any of the
foregoing remedies shall not preclude pursuit of any other remedies provided by
law, nor shall pursuit of any remedy provided in this Lease constitute a
forfeiture or waiver of any monthly installment of Rent due to Landlord under
this Lease or of any damages accruing to Landlord by reason of the violation of
any of the terms, provisions and covenants contained in this Lease. Failure by
Landlord to declare any Event of Default immediately upon its occurrence, or
failure to enforce one or more of Landlord's remedies, or forbearance by
Landlord to enforce one or more of Landlord's remedies upon an Event of Default
shall not be deemed or construed to constitute a waiver of an Event of Default
or waiver of any violation or breach of terms of this Lease. Pursuit of any one
of the above remedies shall not preclude pursuit by Landlord of any of the other
remedies provided in this Lease. The loss or damage that Landlord may suffer by
reason of termination of this Lease or the deficiency from any re-letting as
provided for above shall include the expense of repossession and any repairs or
reasonable remodeling undertaken by Landlord following possession. If Landlord
terminates this Lease at any time for any Event of Default, in addition to other
Landlord's remedies, Landlord may recover from Tenant all damages Landlord may
incur by reason of the Event of Default, including the cost of recovering the
Premises and the Rent then remaining unpaid.

10.03. By Landlord. Landlord shall be in default of this Lease if Landlord
should fail to perform any of Landlord's obligations and covenants under the
Lease and such failure should continue for a period of thirty (30) days after
delivery of written notice from Tenant to Landlord to correct Landlord's failure
to perform, or for a period of forty-eight (48) hours in the event of an
emergency. However, if Landlord's nonperformance reasonably requires more than
thirty (30) days to cure, or more than forty-eight (48) hours in the event of an
emergency, Landlord shall
<PAGE>

not be in default if curative action is commenced by Landlord within the thirty
(30) day period, or within forty-eight (48) hours in the event of an emergency,
and is thereafter diligently pursued to completion.

10.04. Remedies Against Landlord. If Landlord should be in default of its
obligations under the Lease, as provided in Section 10.03 herein, Tenant shall
have the right, but not the obligation, to take all reasonable and necessary
action to correct Landlord's default and to be reimbursed by Landlord for all
actual and direct costs and expenses incurred by Tenant, not including any
consequential damages. Tenant shall have no right of offset against its monetary
obligations hereunder, except that Tenant shall have a right of offset as to its
monetary obligations hereunder if Landlord should wrongfully withhold payment of
the $442,000.00 contribution for Tenant improvements (Section 4.04).

10.05. Limitation of Landlord's Liability. Any damages recoverable by Tenant
hereunder, as provided in Section 10.04, shall be recoverable only from the
Landlord's monetary assets and Landlord's interest in the Premises, including
all insurance proceeds and condemnation proceeds relating thereto, there being
no liability as to the equity interest owners of Landlord.

Article XI: Casualty to Premises

11.01. Damage/Repair. In the event that the Building of the Premises or any part
thereof shall be damaged by fire or other casualty, Tenant shall give prompt
written notice thereof to Landlord. Within thirty (30) days of receipt of
Tenant's notice of fire or other casualty, Landlord shall notify Tenant as to
the amount of time projected to restore the Premises to a reasonable state of
usability. If it is projected that: the Premises cannot be so restored within
one hundred twenty (120) days of the event of casualty, both Landlord and Tenant
shall have the right to terminate the Lease effective on the date of casualty.
In the event that the projected time for restoration is less than one hundred
twenty (120) days from the event of casualty, Landlord shall proceed with the
restoration of the Premises, and if such is not completed to a reasonable state
of usability within one hundred twenty (120) days of the event of casualty,
Tenant shall have the right to terminate the Lease effective on the date of
casualty, which notice of termination must be in writing and delivered to
Landlord within twenty (20) days of the one hundred twentieth (120th) day
following the event of casualty, or such right to terminate is waived. Landlord
shall not be required to rebuild, repair, or replace any part of the furniture,
equipment, or other personal property or any trade fixtures and other
improvements which may have been placed by Tenant within the Building or the
Premises.

11.02. Reduction of Rent. If the Building is to be rebuilt or repaired, Landlord
shall allow Tenant a fair diminution of Rent during the time and to the extent
the Premises are unfit for occupancy, based on the area affected and the period
of time so affected. To the extent that Tenant has insured Tenant's personal
property and improvements which are not to become the property of Landlord at
the end of the Lease, the proceeds of said insurance shall go to Tenant.

<PAGE>
Article XII: Eminent Domain

12.01. Total/Substantial Taking. If during the term of the Lease or any
extension thereof, all or a substantial part of the Premises are taken for any
public or quasi-public use under any governmental law, ordinance or regulation
or by right of eminent domain, or are conveyed to the condemning authority under
threat of condemnation, this Lease shall terminate and the monthly installments
of Rent shall be abated during the unexpired portion of the term of the Lease,
effective from the date of the taking.

12.02. Partial Taking. If more than twenty-five percent (25%) of the Premises
is taken, either Landlord or Tenant may terminate this Lease by written notice
to the other within thirty (30) days after such taking has occurred. If the
Lease is not terminated by Landlord or Tenant within thirty (30) days after such
taking has occurred, Landlord shall promptly, at Landlord's expense, restore and
reconstruct the buildings and improvements (including leasehold improvements
made by Tenant or any assignee, subtenant or other occupant of the Premises)
situated on the Premises in order to make the same reasonably tenantable and
suitable for the use for which the Premises is leased as defined in Section
8.01.

12.03. Adjustment of Rent. In the event of a termination of the Lease, the
monthly installments of Rent payable under this Lease during the unexpired
portion of the term of the Lease shall be adjusted equitably. Landlord and
Tenant shall each be entitled to receive and retain such separate awards and
portions of lump sum awards as may be allocated to their respective interests in
any condemnation proceeding. The termination of this Lease shall not affect the
rights of the parties to such awards.

Article XIII: Environmental Matters

13.01. Tenant Compliance. Subject to the provisions set forth hereinafter in
Sections 13.03 and 13.04, Tenant, at Tenant's expense, shall comply with all
laws, rules, orders, ordinances, regulations and requirements of federal, state,
county and municipal authorities pertaining to Tenant's use of the Premises,
regardless of when they become effective, including, without limitation, all
applicable federal, state and local laws, regulations or ordinances pertaining
to air and water quality, Hazardous Materials (as defined in section 13.06),
waste disposal, air emissions and other environmental matters, all zoning and
other land use matters, and with any direction of any public officer or
officers, pursuant to law, which impose any duty upon Tenant with respect to its
use or occupancy of the Premises. Tenant agrees to take the Premises pursuant to
this Lease subject to all recorded covenants, conditions and restrictions
described in Section 16.10 and scheduled on Exhibit C: attached hereto.

13.02. Indemnity by Tenant. Tenant does hereby forever indemnify and hold
Landlord harmless from any and all claims and causes of action, including
defense costs with counsel of Landlord's own choosing, arising out of Tenant's
breach of its covenants related to Hazardous Materials set forth in Sections
2.03 and 8.06 herein.

13.07. Survival. The representations and indemnities contained in this Article
XIII shall survive the expiration or termination of this Lease.
<PAGE>

Article XIV: Subordination, Attornment, Non-Disturbance and Estoppels

14.01. Subordination. Tenant agrees to subordinate its interest in this Lease'
to any deed of trust, mortgage, ground lease or other security instrument that
now or hereafter covers any portions of the Premises, provided that the secured
lender thereunder agrees to provide a nondisturbance agreement as described in
Section 14.03 below.

14.02. Attornment. Tenant shall attorn to any successor to Landlord's interest
as the owner of the Premises and landlord of this Lease, who recognizes this
Lease and Tenant's rights hereunder, whether such succession is the result of a
purchase, foreclosure, deed in lieu of foreclosure, power of sale, or otherwise,
and upon such successor's request and Tenant's receipt of adequate documentation
confirming the transition of Landlord's interest to any such successor, and the
recognition of this Lease and Tenant's rights hereunder, Tenant shall execute
such agreements or documents, as may be reasonably requested by the successor,
confirming Tenant's attornment.

14.03. Non-Disturbance. Within sixty (60) days of the effective date of the
Lease, Landlord shall provide to Tenant from any secured lender holding a deed
of trust, mortgage or other security instrument, a non-disturbance agreement in
recordable form as to allow Tenant to continue forward under this Lease without
interruption or modification in the event that any such secured lender should
succeed to Landlord's ownership interest in the Premises, which nondisturbance
agreement shall specifically state that Tenant's rights hereunder shall be
recognized, Tenant's possession shall not be disturbed, as long as Tenant has
not committed an Event of Default hereunder, and that Tenant shall not be
included as a party defendant with regard to any legal actions by the lender
against Landlord. In the event that Landlord is not successful in obtaining the
aforementioned recordable non-disturbance agreement within sixty (60) days of
the effective date of the Lease, Landlord agrees to refinance any indebtedness
secured by the Premises with a lender, which is willing to provide a recordable
non-disturbance agreement, within two hundred forty (240) days of the effective
date of the Lease.

14.04. Estoppel Certificates. Tenant shall at any time and from time to time,
upon not less than ten (10) days prior written request by Landlord, execute,
acknowledge and deliver to Landlord a statement in writing certifying that this
Lease is unmodified and in full force and effect (or if there have been any
modifications, that the same is in full force and effect as modified and stating
the modifications), and the dates to which the Rent and any other charges have
been paid, and either stating that to the knowledge of Tenant no default exists
hereunder or specifying each such default known to Tenant, it being intended
that any such statement delivered pursuant to this paragraph may be relied upon
by any prospective purchaser of the Premises or any other prospective successor
to Landlord. Likewise, upon ten (10) days prior written request by Tenant,
Landlord shall provide to Tenant the same sort of statement certifying the
matters aforementioned.

Article XV: Professional Services

15.01. Landlord Broker. Landlord hereby represents that Landlord has engaged
only the firm of Columbine United Companies, Inc. (Edward W. Martin, President)
("Columbine") to function as the exclusive listing agent and the lease broker
representative for Landlord, pursuant to the

<PAGE>

provisions of that certain Listing Agreement between Landlord and Columbine
dated August 1, 2000, the provisions of which shall be binding upon and inure to
the benefit of Landlord and Columbine and their respective successors and
assigns.

15.02. Tenant Broker. Tenant hereby represents that Tenant has engaged only The
Morse Company (Scott Morse) ("Morse") to function as the exclusive lease broker
and representative for Tenant, pursuant to written agreement between Tenant and
Morse.

15.03. Commissions. Landlord shall be paying a commission to Columbine as
provided in the aforementioned agreement between Landlord and Columbine, there
being no contractual obligation on the part of Landlord to pay any commission to
Morse. Morse shall be paid by Columbine a share of Landlord's commission to
Columbine, as may be agreed between Columbine and Morse.

15.04. Indemnity. Tenant hereby expressly indemnifies and holds Landlord and
Columbine harmless from any claims for commissions, including defense costs by
counsel of Landlord's and Columbine's choosing, which may be asserted by any
other brokers claiming status as a legitimate representative of Tenant.
Likewise, Landlord hereby expressly indemnifies and holds Tenant harmless from
any claims for commissions, including defense costs by counsel of Tenant's
choosing, which may be asserted by any other brokers claiming status as a
legitimate representative of Landlord.

XVI: Miscellaneous

16.01. Force Majeure. Whenever a period of time is prescribed herein for action
to be taken by Landlord or Tenant (except for Tenant's obligation to pay Rent
and either party's other monetary obligations due hereunder), then neither
Landlord nor Tenant shall be responsible or accountable for any delays caused by
riots, strikes, acts of war, acts of God and intervening governmental laws and
regulations or any other kind of intervening circumstances which are beyond the
control of Landlord and/or Tenant. In the event that a casualty should occur to
the Premises requiring repair/restoration of the Premises, as provided in
Article XI herein, an intervening force majeure event shall not toll the running
of the time permitted to repair or restore the Premises more than sixty (60)
days.

16.02. Severability. A determination by a court of competent jurisdiction that
any provision of this Lease is not valid or enforceable shall not cancel or
invalidate the remaining provisions of the Lease, which shall remain in full
force and effect.

16.03. Attorney's Fees. In the event that a dispute or controversy should
develop between Landlord and Tenant as to any matters relating to this Lease,
and if said disagreement should result in litigation, the prevailing party shall
be entitled to recover from the other party its reasonable and necessary
attorney's fees, expenses and costs, including any such expenditures which may
be incurred in advance of the commencement of litigation.

16.04. Notices. All notices required by this Lease or which may be sent by
Landlord or Tenant to the other with regard to any matters under this Lease,
shall be sent to Landlord and Tenant at the
<PAGE>

addresses and to the persons set forth below. Any such notices shall be
effective if delivered by certified mail (return receipt requested), hand-
delivery or recognized private overnight courier providing evidence of delivery.
The address and person(s) to receive any such notices may be changed by prior
written notice from either Landlord or Tenant to the other.

Landlord:

Edward W. Martin, Jr., President
Columbine United Companies, Inc.
6757 Arapaho Road, Suite 711, LB 386
Dallas, Texas 75248

with copy to:

Devcor Equities, Inc.
100 Alexis Nihon Boulevard, Suite 290
St. Laurent, Quebec
Canada H4M 2N7
Attention:  J.P. Di Blasio

Tenant:

1303 Arapaho
Richardson, Texas 76081
Attention: Tyler Dawson
Vice President Operations

16.05. Time of the Essence. As to all provisions in this Lease for which a
period of time is stated, it is agreed that time is of the essence, and Landlord
and Tenant are obligated to perform any such provisions in the prescribed time.

16.06. Authority to Bind. The individual signatories to this Lease on behalf of
Landlord and Tenant hereby expressly represent and warrant that they have the
authority to act for and execute this Lease for the party for which they signed
and to bind said party to the provisions herein.

16.07.  Binding Effect. This Lease shall be binding upon and inure to the
benefit of Landlord and Tenant and their respective successors and assigns.

16.08.  Interpretation. The provisions of this Lease shall be interpreted and
enforced pursuant to the applicable laws of the state of Texas.

16.09.  Landlord's Representations, Warranties and Covenants. Landlord
represents and warrants that:

(a) Landlord has full right and lawful authority to enter into and perform the
Landlord's obligations under this Lease for the full term hereof and has good
and marketable title to the
<PAGE>

Premises in fee simple, free and clear of all contracts, leases, tenancies,
agreements, easements, restrictions upon use or occupancy or other restrictions,
violations, mortgages and other liens, encumbrances or exceptions to title of
any nature whatsoever affecting the Premises or the easements, rights and
privileges herein granted to Tenant with respect to the Premises, except for the
matters specifically set forth on Exhibit C hereto;

(b)  the Premises is zoned in conformity with applicable laws in a manner
permitting the use of the facilities constructed thereon for the Permitted Uses;

(c) the operation of said facilities in accordance with the provisions of this
Lease will not violate any presently existing laws, ordinances, orders, rules or
regulations of any governmental authority, agency or instrumentality having
jurisdiction over any part of the Premises;

(d)  all access roads within the Premises shown on Exhibit B hereto as leading
to public streets afford legal access to the public right-of-way of such
streets.

Landlord also warrants and covenants that:

(e) this Lease is not and shall not be subject or subordinate to any mortgage
not listed on Exhibit C hereto except for such subordination as may be
accomplished in accordance with the provisions of Article XIV of this Lease
captioned "Subordination, Attornment, Non-Disturbance and Estoppels"; and

(f)  a memorandum of this Lease shall be recorded ahead of any mortgage not
listed on Exhibit C hereto which affects the Premises or any part thereof.

Landlord further covenants that if Tenant discharges the obligations herein set
forth to be performed by Tenant, Tenant shall have and enjoy, during the term
hereof, the quiet and undisturbed possession of the Premises and all easements
and appurtenances appertaining thereto.

16.10. Exhibits. There are three (3) exhibits to this Lease. Exhibit A is a
legal description of the Premises. Exhibit B is a Site Plan of the Premises.
Exhibit C includes certain representations, warranties and covenants of
Landlord.

16.11.  Complete Agreement. This instrument represents the complete agreement of
lease between Landlord and Tenant and shall not be amended, supplemented or
otherwise modified except by further written agreement of the parties. Neither
party has been influenced to enter into this Lease in reliance upon any
statements or representations, oral or written, by either Landlord or Tenant or
by any other person or entity, not otherwise expressly set forth herein.
<PAGE>

EXECUTED to be effective the date set forth on the first page of this Lease:

LANDLORD:

EAST COLLINS, L.P., a Texas Limited
Partnership

BY:   Devcor Equities, Inc., a Texas
      Corporation and General Partner

      By:    /s/ J.P. DiBlasio
          ---------------------------

      Its:   Executive Vice President
          ---------------------------

TENANT:

CHORUM TECHNOLOGIES, INC.,
a Delaware Corporation

By:    /s/ Tyler Dawson
    ---------------------------------

Its:    Vice President of Operations
    ---------------------------------
<PAGE>

EXHIBIT A

BEING all that tract of land in the City of Richardson, DALLAS County, Texas, a
part of the JESSE N. EVERETT SURVEY, ABSTRACT NO. 440, and being Lot 1, Block F,
CENTRAL PARK, as Addition to the City of Richardson as recorded in Volume 83118,
Page 1449, DALLAS County Map Records, and being all that tract of land conveyed
to Confederation Life Insurance Company as recorded in Volume 91027 Page 3055,
DALLAS County Deed Records, an being further described as follows:

BEGINNING at a 1/2 inch iron rod found at the southwest corner of said Lot 1,
said point being the intersection of the north line of Collins Boulevard (a 100
foot wide right of way) with the east line of International Parkway (a 60 foot
wide right of way);

THENCE along the east line: of International Parkway and along the west line of
said Lot 1 as follows:

North 00 degrees 38 minutes 41 seconds East, 50.00 feet to a "X" in a concrete
driveway found for corner;

Northeasterly, 252.28 feet along a curve to the right which has a central eagle
of 45 degrees 10 minutes 13 seconds, a radius of 320.00 feet, a tangent of
133.11 feet, and whose chord bears North 23 degrees 13 minutes 48 seconds East,
245.80 feet to a "X" in a concrete driveway found for corner;

Northeasterly, 285.41 feet along a curve to the left which has a central angle
of 04 degrees 13 minutes 12 seconds, a radius of 3875.00 feet a tangent of
142.77 feet, and whose chord bears North 43 degrees 42 minutes 21 seconds East,
285.35 feet to a "V" is a concrete headwall found at the northwest corner of
said Lot l;

THENCE South 55 degrees 16 minutes 42 seconds East, 856.02 feet along the north
line of said Lot 1 to a 1/2 inch iron rod found in a corner clip at the
intersection of the north line of said Collies Boulevard with the west line of
Glenville Drive (an 80 foot wide right of way);

THENCE South 45 degrees 31 minutes 45 seconds West, 8.19 feet along said corner
clip to a "X" in a concrete sidewalk found for corner in the north line of said
Collins Boulevard;

THENCE North 89 degrees 21 minutes 19 seconds West, 992.48 feet along the north
line of said Collies Boulevard and along the south line of said Lot 1 to the
POINT OF BEGINNING and CONTAINING 267,378 square feet or 6.138 acres of land,
more or less.
<PAGE>

EXHIBIT C

TITLE EXCEPTIONS

1.  Deed of Trust executed by EAST COLLINS, L.P., a Texas limited partnership to
TIMOTHY R. BROWN, Trustee(s), securing CONFEDERATION LIFE INSURANCE COMPANY in
the payment of one note in the principal sum of $1,781,750.00, and other
indebtedness and performance as therein provided, which Deed of Trust is dated
March 1, 1994, filed of record on March 3, 1994, and recorded in Volume 94041,
Page 04443, Deed of Trust Records, DALLAS County, Texas; additionally secured by
vendor's lien retained in Deed by CONFEDERATION LIFE INSURANCE COMPANY, recorded
in Volume 94041, Page 04434, Deed Records, DALLAS County, Texas.

2.  5 foot utility easement along the South, West and Northwest sides, per Plats
recorded in Volume 73245, Page 1642, and Volume 83118, Page 1449, Map Records,
DALLAS County, Texas.

And also as shown on survey by DAN H. RAMSEY, Registered Professional Land
Surveyor, #4172, dated November, 1993.

3.  55 foot Drainage easement along the Northeast side, per Plats recorded in
Volume 73245, Page 1642, and Volume 83118, Page 1449, Map Records, DALLAS
County, Texas.

And also as shown on survey by DAN H. RAMSEY, Registered Professional Land
Surveyor, #4172, dated November 1993.

4.  24 foot Firm Lane easement along part of South side, per Plat recorded in
Volume 83118, Page 1449, Map Records, DALLAS County, Texas.

And also as shown on survey by DAN H. RAMSEY, Registered Professional Land
Surveyor, #4172, dated November, 1993.

5.  Telephone line easement as granted to SOUTHWESTERN BELL TELEPHONE COMPANY,
dated November 9, 1981, filed December 9, 1981, recorded in Volume 81239, Page
1933, Deed Records, DALLAS County, Texas.

And across the most eastern corner, as shown on survey by DAN H. RAMSEY,
Registered Professional Land Surveyor, #4172, dated November 1993.

6.  Easement created in instrument executed by TRINITY PROPERTIES, LTD. To TEXAS
POWER & LIGHT COMPANY for 10 foot easement for electric service, dated August,
1983, filed September 20, 1983, recorded in Volume 83185, Page 2991, Deed
Records, DALLAS County, Texas.

7.  Easement created in instrument executed by TRINITY PROPERTIES, LTD. To PARK
PACIFIC, LTD. For 20 foot drainage and utility easement, dated August 17, 1984,
filed
<PAGE>

September 21, 1984, recorded in Volume 84187, Page 2639, Deed Records, DALLAS
County, Texas.

Shown as 20 foot Easement in east portion, as shown on survey by DAN H. RAMSEY,
Registered Professional Land Surveyor, #4172, dated November, 1993.

8.  The Floodway/Drainage Easement requirements by the City of Richardson, in
its approval of the Plat recorded in Volume 83118, Page 1449, Map Records,
DALLAS County, Texas, that requires the property owner to maintain the creek,
creeks, or drainage channel as an open channel and reserving the right of
ingress and egress for purposes of inspection, supervision of maintenance and to
alleviate any undesirable conditions.

9.  The following matters as shown on survey by DAN. H. RAMSEY, Registered
Professional Land Surveyor, #4172, dated November, 1993:

a.  Sidewalk encroachment across southwest and Southeast corners;

b.  Common concrete flume along Northeast side, together with laterals across
    property;

c.  Large box culvert and guard rail protrusion onto property to the North in
    East portion;

d.  Large box culvert and guard rail protrusion into Collins Boulevard in East
    portion.

Landlord represents and warrants with respect to the above described title
exceptions that (i) nothing contained in any of said exceptions prohibits or
restricts Landlord from performing any or all of its obligations under this
Lease during the full term thereof, (ii) none of said exceptions adversely
affects or interferes with Tenant's enjoyment of the Premises or the exclusive
and non-exclusive easements, rights and privileges granted to Tenant by this
Lease, and (iii) there are no easements under, above or through the Building.
<PAGE>

After recording, return to:

Stewart Wayne, Esq.
Gardere & Wynne, L.L.P.
1601 Elm Street, Suite 3000
Dallas, Texas 75201

1089 East Collins
Richardson, Texas

MEMORANDUM OF LEASE

MEMORANDUM OF LEASE, dated as of October 10, 2000, between East Collins, L.P., a
Texas limited partnership, having an address: c/o Devcor Equities, Inc., 100
Alexis Nihon Blvd., Suite 290, St. Laurent, Quebec, Canada H4M 2N7, Attention:
J. P. Di Blasio ("Landlord"), and Chorum Technologies, Inc., a Delaware
corporation, having a mailing address of 1303 Arapaho, Richardson, Texas 76081
Attention: Tyler Dawson, Vice President-Operations ("Tenant").

WITNESSETH:

For and in consideration of the sum of Ten Dollars and other valuable
consideration paid by Tenant to Landlord, the receipt and sufficiency of which
are hereby acknowledged:

1. Landlord by lease bearing even date herewith (the "Lease"), has demised and
leased to Tenant and Tenant has leased from Landlord, and Landlord hereby
demises and leases to Tenant and Tenant hereby leases from Landlord, upon and
subject to the terms, covenants and conditions set forth in the Lease certain
premises (the "Premises") consisting of the parcel of land (the "Land")
described in Exhibit "A" attached hereto and that certain building of
approximately 64,155 square feet and all other improvements located on the Land,
and Landlord hereby grants to Tenant for the hereinafter stated lease term any
and all easements, rights, privileges and appurtenances belonging or
appertaining to the Premises.

TO HAVE AND TO HOLD the same, as provided in Section 1.05 of the Lease, for a
term commencing on the effective date of the Lease and expiring on a date seven
(7) years from the first day of the first month immediately following the Rental
Commencement Date, as defined in Section 1.06 of the Lease; provided, however,
that if such Rental Commencement Date is the first day of a month, the term of
the Lease shall continue thereafter to and including the date which is seven (7)
years from the Rental Commencement Date. In that regard, Section 1.06 of the
Lease provides that the Rental Commencement Date shall be the earliest of (a)
January 1, 2001, (b) ninety (90) days after the effective date of the Lease, or
(c) thirty (30) days after (i) the Phase I assessment, required by Section 13.05
of the Lease, is completed reflecting no environmental deficiencies requiring
remediation, or (ii) the satisfactory completion of remediation work arising
from the Phase I assessment.
<PAGE>

2. Landlord by the Lease has granted, and Landlord hereby grants to Tenant, one
(1) successive option to extend such lease term, for a separate additional
period of five (5) years, from the date upon which such term would otherwise
expire, such option to be exercised by Tenant's notifying Landlord of such
exercise in the manner specified in the Lease at least one hundred eighty (180)
days before the beginning of the additional period for which such term is to be
so extended and each such extension to be upon and subject to the terms,
covenants and conditions stated in the Lease.

The parties hereto by reference incorporate herein all the terms, covenants, and
conditions contained in the Lease and agree to observe, conform to and comply
with such terms, covenants and conditions on the part of each to be observed and
performed. For a complete statement of the rights, privileges and obligations
created under and by said instrument and of the terms, covenants and conditions
contained therein, reference is hereby made to the Lease.

IN WITNESS WHEREOF, Landlord and Tenant have caused this Memorandum of Lease to
be duly executed and sealed as of the day and year first above written.

LANDLORD:

EAST COLLINS, L.P.,
a Texas limited partnership

By:   Devcor Equities, Inc.,
      A Texas corporation
Its:  General Partner

      By:    /s/ J.P. DiBlasio
         -----------------------------

      Its:    Executive Vice President
         -----------------------------

TENANT:

CHORUM TECHNOLOGIES, INC.,
a Delaware Corporation

By:    /s/ Tyler Dawson
    ----------------------------------

Its:    Vice President of Operations
    ----------------------------------
<PAGE>

STATE OF       )
               )SS:
COUNTY OF      )

On this the 10th day of October, 2000, before me a Notary Public, duly
authorized in and for the said County and in the State aforesaid to take
acknowledgments, personally appeared J.P. Di Blasio, to me known and known to me
to be President of Devcor Equities, Inc., a Texas corporation, as general
partner of East Collins, L. P., a Texas limited partnership, and acknowledged
that as such officer, being authorized so to do, he executed the fo regoing
instrument on behalf of said corporation and limited partnership as his free and
voluntary act, and as the free and voluntary act of said corporation and limited
partnership, for the uses and purposes therein set forth.

IN WITNESS WHEREOF, I hereunto set my hand and official seal.

My Commission Expires:

_______________________________           __________________________________

STATE OF       )
               )SS:
COUNTY OF      )

On this the 6th day of September, 2000, before me a Notary Public, duly
authorized in and for the said County and in the State aforesaid to take
acknowledgments, personally appeared Tyler Dawson, to me known and known to me
to be V.P. Operations of Chorum Technologies, Inc., a Delaware and acknowledged
that as such officer, being authorized so to do, he executed the foregoing
instrument on behalf of said corporation as his free and voluntary act, and as
the free and voluntary act of said corporation, for the uses and purposes
therein set forth.

IN WITNESS WHEREOF, I hereunto set my hand and official seal.

My Commission Expires:

______________________________            _________________________________<PAGE>

                                                                   Exhibit 10.11

                           David Nichols Realty, Inc.

71 East Pennington         Tucson, Arizona 85701                 520-624-0426

                           COMMERCIAL LEASE AGREEMENT

                                    Between

                             Larry Michael Sandusky
                                       &
                             Rebecca Anne Sandusky
                                            Landlord
--------------------------------------------------------------------------------

                                      and

                        Chorum Technologies Inc., Tenant

--------------------------------------------------------------------------------

                                     Dated

                                June 8th, 2000
<PAGE>

                          COMMERCIAL LEASE AGREEMENT

                                     INDEX

<TABLE>
<S>  <C>                                                          <C>
 1.  LEASED PREMISES                                              1

 2.  USE OF LEASED PREMISES                                       1

 3.  ZONING                                                       1

 4.  COMPLIANCE WITH LAWS                                         1

 5.  CONDUCT OF BUSINESS                                          1

 6.  TERM                                                         2

 7.  RENT                                                         2

 8.  MONTHLY RENTAL PAYMENTS                                      2

 9.  SECURITY DEPOSIT                                             2

10.  WHERE PAYABLE                                                3

11.  MAINTENANCE OF LEASED PREMISES                               3

12.  UTILITIES AND GLASS                                          3

13.  ADVANCE POSSESSION                                           3

14.  ALTERATIONS AND ADDITIONS                                    3

15.  LIENS CREATED BY TENANT                                      4

16.  LEAKING ROOF                                                 4

17.  DAMAGE OR INJURY TO PERSONS OR PERSONA L PROPERTY            4

18.  LANDLORD RULES                                               4

19.  LIABILITY INSURANCE                                          4

20.  LANDLORD'S EXEMPTION FROM LIABILITY                          5

21.  LANDLORD'S CASUALTY INSURANCE                                6

22.  INSPECTIONS                                                  6

23.  FIRE OR EQRTHQUAKE                                           6

24.  LIGHTING AND OTHER FIXTURES                                  6

25.  BANKRUPTCY                                                   6

26.  WAIVER BY LANDLORD                                           7

27.  LEASE TRANSFER                                               7

28.  REASONABLE CONSENT                                           8

29.  TENANT CONTINUING RESPONSIBILITY                             8

30.  ENFORCEMENT OF LEASE                                         8

31.  CHANGE IN LEASE                                              8
</TABLE>
<PAGE>

<TABLE>
<S>  <C>                                                          <C>
32.  CONTINUING LEASE AFTER EXPIRATION                            8

33.  SUIT TO ENFORCE TERMS OF LEASE                               8

34.  POSSESSION AT EXPIRATION OF THIS LEASE                       9

35.  IF LANDLORD CANNOT DELIVER POSSESSION OF LEASED PREMISES     9

36.  INDEPENDENT COVENANT FOR PAYMENT OF RENT                     9

37.  IF LEASED PREMISES ARE DESERTED BY TENANT                    9

38.  LANDLORD'S RIGHT TO PLACE "FOR SALE" OR "FOR LEASE" SIGN     9

39.  RETROACTIVE RENT CLAUSE                                      9

40.  BROKERAGE FEE                                                9

41.  SUBMISSION OF LEASE                                         10

42.  GENDER                                                      10

43.  SIDE HEADINGS                                               10

44.  MORTGAGE                                                    10

45.  SIGNS                                                       10

46.  KEEPING LEASED PREMISES CLEAN                               11

47.  NON-PAYMENT OF RENT                                         11

48.  LANDLORD'S DAMAGES                                          11

49.  EQUIPMENT, ROOF, WALLS AND OTHER REPAIRS                    11

50.  FINANCIAL STATEMENT                                         12

51.  DISCLAIMERS                                                 12

52.  TIME OF ESSENCE                                             12

53.  BINDING ON HEIRS, ETC.                                      12

54.  TENANT IMPROVEMENTS                                         12

55.  LANDLORD'S LIEN                                             12

56.  AMERICANS WITH DISABILITIES ACT                             12

57.  CONDITION OF LEASED PREMISES                                12

58.  HAZARDOUS WASTE                                             13

59.  CONDEMNATION                                                13

60.  NOTICES                                                     14

61.  LANDLORD'S DEFAULT                                          14

62.  WARRANTY OF AUTHORITY                                       14

63.  FORCE MAJEURE                                               14
</TABLE>

<PAGE>

COMMERCIAL LEASE AGREEMENT

     THIS LEASE, made this 8th day of June 2000 between Larry Michael Sandusky &
Rebecca Anne Sandusky (hereinafter called "LANDLORD"), AND Chorum Technologies,
Inc., (hereinafter called "TENANT"), and David Nichols Realty, Inc (hereinafter
called "PROCURING BROKER" or "AGENT").

     1.  LEASED PREMISES: Landlord hereby leases to Tenant and Tenant leases
from Landlord for the term, at the rental, and upon all the conditions set forth
herein, that certain real property situated in the County of Pima, State of
Arizona, commonly known as:

            221 E. 6th Street, in the County of Pima, City of Tucson, State of
Arizona

and described on Exhibit A attached, Leased Premises outlined in yellow hereto
and made a part hereof. Said real property including the land and all
improvements thereon, is herein called the "Leased Premises."

     2.  USE OF LEASED PREMISES. The Leased Premises shall be used only as:

                        Office and Light Manufacturing

     3.  ZONING. It is agreed that the zoning has been investigated by Tenant
and determined by the Tenant to be correct, in all respects, for the business
use as stated herein.

     4.    COMPLIANCE WITH LAWS. The Tenant agrees to conduct the business in a
legal manner and in accordance with Municipal, County, State and Federal
regulations and requirements, and to Zoning ordinances.

           The Tenant shall faithfully and promptly execute and comply with all
present and future statutes, ordinances, soles, orders, regulations and
requirements of the Federal, State, City and County authorities and o(Pounds)
any and all their departments and bureaus applicable to said Leased Premises
and the use thereof. Should the Tenant, or the Health, building or City, County,
State or Federal authorities require any changes or improvements in or to the
Leased Premises, the Tenant shall first obtain the written consent from the
Landlord for such changes, and all such changes or improvements shall be done at
the sole expense and risk of the Tenant. The Tenant agrees to comply with all
provisions, covenants, conditions and restrictions as recorded in the office of
the County Recorder of Pima County, Arizona. Any interruption or stoppage in the
use and occupancy of the Leased Premises shall not affect the rental terms,
conditions and covenants contained in this Lease.

     5.    CONDUCT OF BUSINESS. Tenant shall not leave the Leased Premises
unoccupied or vacant but shall throughout the term of this Lease conduct and
carry on the type of business for which the Leased Premises are leased at its
usual business hours and manner.
<PAGE>

     6.  TERM. TO HAVE AND HOLD the same to the said Tenant from the 8/th/ day
of June, 2000 through the 8/th/ day of October, 2000.

     7.  RENT. And the said Tenant, in consideration of the leasing of the
premises hereinabove set forth, covenants anal agrees with the Landlord to pay
the said Landlord as! Rent for , the property the total suns of Thirty Two
Thousand Four Hundred Sixty Eight Dollars and Ninety-Six Cents ($32,468.96)
lawful money of the United States of America, which amount is now due and
payable.

     8.  The above rent includes an amount presently equal to Two percent (2%)
of the gross monthly rent (gross monthly rent shall include rent and Tenant's
m6nthly payment of real property tax and insurance reimbursement as described
below), which. amount is for the TWO percent (2 %) "Business Privilege License
Tax" as imposed by the City of Tucson. In the event the City ,or State, or both,
should impose an increase or additional tax, the Tenant agrees to pay said
increase and such additional tax. The Landlord, in turn, shall pay these amounts
to the proper Governmental body. Said tax, as of the date of this Lease, is One
Hundred Fifty Nine Dollars and Sixteen Cents ($159.16) per month. The Tenant
hereby agreed to pay any and all other taxes levied or assessed by State,
County, and/or City or Federal authorities applying to or affecting the Leased
Premises, including all taxes on all merchandise and stock and all taxes on all
equipment as owned by Tenant or on Landlord's equipment used by Tenant, and to
pay all license, fees, sales taxes for conducting the business.

     Tenant agrees to pay as part of the above rent amount any real property
taxes levied for the 2000 tax year, prorated as of 2000. Tenant shall pay his
share of the annual real property tax only for the term of the lease. It shall
be computed on a prorated share of square footage per unit, if there are
multiple units. Tenant's percentage of their space to total property is 47% as
designated by Tax Code # ###-##-####. Taxes for the 2000 Tax Year are $12,500.
The monthly cost is Four Hundred Eighty Nine Dollars and Fifty Eight Cents
($489.58) per month for each month of the lease.

     Tenant agrees not to deduct from the herein rental payments any cost or
expense whatsoever involving repairs, maintenance or alterations to, the Leased
Premises or for anything else, unless written consent is first obtained by the
Tenant from the Landlord or from the Agent.

     9.  SECURITY DEPOSIT. On or before the date of execution of this Lease,
Tenant will deposit with the Landlord the total sum of Eight Thousand One
Hundred Seventeen Dollars and Twenty Four Cents ($8,417.24) (herein after
referred to as "Security Deposit").

     Security Deposit shall be held by the Landlord as Security for the faithful
performance by Tenant of all the terms and conditions of this Lease to be kept
and performed by Tenant during the term hereof. If Tenant defaults with respect
to any provisions of this Lease, including; but not. limited to the provisions
relating to the payment of rent, Landlord may (but shall not be required to)
use, apply or retain all or any part of this Security Deposit for the payment of
any rent or other sums in default, or for the, payment of any amount which
Landlord may spend or become obligated to spend by reason of Tenant's default ,
or to compensate Landlord for any other loss or damage which Landlord may suffer
by reason of Tenant's default. If any portion of said deposit is so used or
applied Tenant shall, within 5 days (5) days after written demand therefor
deposit cash with Landlord in an amount sufficient to restore the Security
Deposit to its original amount and Tenant's failure to do so shall be a default
under this lease. Landlord shall not be required to keep this Security Deposit
separate from its general funds, and Tenant shall not be entitled to interest on
such deposit.  If Tenant shall fully and faithfully perform every provision of
this lease to be performed by it, the Security Depositor any balance thereof
shall be returned to Tenant (or, at Landlord's option, to the last assignee of
tenant's interest hereunder) within ten (10) days following expiration of this
Lease term. In the event of termination of Landlord's interest in this Lease,
Landlord
<PAGE>

shall transfer said Deposit to Landlord's successor in interest and shall have
no further obligation with respect thereto.

     10.  WHERE PAYABLE. All rental payments shall be made payable to the order
of

                               Mr. Mike Sandusky
                              1760 Calle Del Voso
                            Tucson, Arizona  85737
          During the entire term of this Lease, unless otherwise designated by
Landlord.

     11.  MAINTENANCE OF LEASED PREMISES. Tenant at all tunes during the term of
Lease, at its own cost and expense, shall keep and maintain or cause to be kept
and maintained in good condition and repair, ordinary wear and tear excepted,
walls, flooring, light fixtures and ceiling tiles, and shall use all reasonable
caution to prevent waste, damage or injury.

     12.  UTILITIES AND GLASS. Tenant further agrees to connect to and pay for
all water, fuel, light, power, gas, telephone, and all other utilities used in
or about the Leased premises and the Landlord shall in no way be responsible
therefor. The Tenant hereby agrees to take full responsibility for all plate
glass and other glass in and about the Leased Premises, and should Landlord
require that plate, glass insurance be carried, the premium shall be paid by the
Tenant.

Tenant shall not overload the electrical systems and shall install, after
obtaining Landlord's prior written approval, any additional wiring required for
Tenant's equipment.

     13.  ADVANCE POSSESSION. All terms of this Lease shall be in force from the
initial date of possession of key or by physical occupancy of Leased Premises by
Tenant. Rent shall continue upon expiration of Lease and until key and
possession of Leased Premises is returned to Landlord.

     14.  ALTERATIONS AND ADDITIONS. Tenant shall not make or allow to be made
any alterations, additions or improvements to or on the Leased Premises or any
part thereof without the written consent of Landlord first had and obtained, and
any alterations, additions or improvements to or of said Leased Premises,
including, but not limited to wall covering, paneling and built-in cabinet work,
but excepting movable furniture and trade fixtures installed by Tenant, shall at
once become a part of the realty as further evidenced by the signing and filing
of a UCC-1 designating the Landlord the Secured Party and shall be surrendered
with the Leased Premises if here is a default in complying with the terms of the
lease. In the event Landlord consents to the making of any alterations,
additions or. improvements to the Leased Premises by Tenant, the same shall be
made by Tenant in a good, workmanlike and diligent manner at Tenant's sole cost
and expense, in accordance with law, with Tenant to obtain all applicable
permits. Upon the expiration or sooner termination of the terns hereof, Tenant
shall, upon written demand by Landlord, given at least thirty (30) days prior to
the end of the term, at Tenant's sole cost and expense, forthwith and with all
due diligence, remove any alterations, additions, or improvements made by
Tenant, designated by Landlord to be removed, and Tenant shall forthwith and
will all due diligence, at its sole cost and expense, repair any damage to the
Leased premises caused by such removal.

     15.  LIENS CREATED BY TENANT. The Tenant shall have no power to do any act
or to make any contract that may create or be the foundation for any lien upon
the Leased Premises or other estate of the Landlord in the Leased premises or
upon any building or improvement thereon, and should any such lien be filed; the
Tenant at his own cost and expense shall bond or otherwise charge the same
<PAGE>

within ten (10) days after the filing thereof. If Tenant fails to do so,
Landlord may (but shall not be obligated to) pay such claim and the amount so
paid together with any costs.

     16.  LEAKING ROOF. The Landlord shall not be responsible for any damage
sustained by the Tenant by reason of water leaking through the roof of said
building.

     17.  DAMAGE OR INJURY TO PERSONS OR PERSONAL PROPERTY. The Tenant hereby
agrees to indemnify, defend and save harmless the Landlord from any and all
liability for any damage or injury to person or property caused by or resulting
from the Tenant's failure to perform any maintenance or repair, as required by
the terms and provisions of this Commercial Lease. The Tenant further agrees to
indemnify, defend and save harmless the Landlord from any and all loss, damage
or liability by reason of any injury or injuries to any person, persons or
personal property occurring by reason of Tenant's use or occupancy or through
the fault or negligence of the Tenant, his employees or patrons. Landlord shall
not be responsible for loss or damage to Tenant or his or anyone else's personal
property on the leased premises, for any reason whatsoever, including but not
limited to, fire, flood, weather, maintenance and structural failure of said
Leased Premises. Tenant is to obtain insurance for his leasehold improvements
and personal property and general liability. If Tenant fails to remove such
personal property prior to expiration of the Term it shall become the property
of the Landlord.

     18.  LANDLORD RULES.  The Landlord reserves the right to make such other
and further reasonable rules and regulations as in its judgment may from time to
time be needful and desirable for the safety, security, care and cleanliness of
the Leased Premises and preservation of good order therein. Said rules must be
presented to Tenant in writing, prior to taking effect.

     19.  LIABILITY INSURANCE. Tenant shall, at Tenant's expense, obtain,
maintain and keep in force, by advance payment of premiums, during the term of
this Lease a policy of comprehensive public liability said property damage
insurance insuring Landlord and Tenant against any liability arising out of the
ownership, use, occupancy or maintenance of the Leased Premises and all areas
appurtenant thereto. Such insurance shall be in the amount of not less than
$1,000,000.00 for injury or death of one person in any one accident or
occurrence and in the amount of not less than $1,000,000.00 for bodily injury or
death for more than one person in any one accident or occurrence. Such insurance
shall further insure Landlord and Tenant against liability for property damage
of at least $250,000.00. Alternatively, limits shall be not less than
$1,000,000.00 bodily injury and property damage liability insurance combined
single limit. The limit of any such insurance shall not, however, limit the
liability of the Tenant hereunder. If the Tenant shall fail to procure and
maintain said insurance the Landlord may procure the same, and Tenant shall be
obligated to reimburse Landlord for the cost thereof, within five days of
receipt of the bill therefore. Insurance required hereunder shall be in
companies rated A+ or better in "Best's Insurance Guide." Tenant shall deliver
to Landlord, prior to right of entry, certificates evidencing the existence and
amounts of such insurance. No policy shall be cancelable or subject to reduction
of coverage or non-renewed without 30 days prior written notice being given to
the Landlord. The insurance provided by Tenant shall specify that it is primary
insurance and any insurance maintained by Landlord shall be in excess and not
contributory with Tenant's insurance. Landlord and Tenant agree that they shall
not be liable to the other and hereby release the other for damage to the Leased
premises and to Tenant's improvements and to loss through business interruption
and to loss to personal property from risks insured against under any insurance
policies carried by the parties and in force at the time of such damage. This
release shall apply only to the extent that such loss is covered by insurance.
Tenant shall also maintain worker's compensation insurance as required by state
law.

     20.  EXEMPTION OF LANDLORD FROM LIABILITY. Tenant agrees Landlord shall not
be liable for injury to Tenant's business or for damage to the goods,
merchandise or other property of and/or
<PAGE>

not liable for injury to the person of Tenant as well as Tenants employees,
agents, invitees, customers, contractors or any other person in or about the
property, including but not limited to a vandal. Such exemption of Landlord from
all liability shall apply whether such damage or injury is caused by or results
from fire, utility related damage, weather related damage such as caused by roof
leak, building or plumbing defect related damage or from any other cause,
including but not limited to, the negligence, and/or any agent of Landlord
including an employee or contractor of Landlord as well as whether any such
damage or injury results from conditions arising upon the property, other
portions of the building of which the property is a part or from other sources
or places and regardless of whether the cause of such damage or injury or the
means of repairing the same is inaccessible to the Tenant.

Further, Tenant agrees to waive any statutory provision, case law or legal
authority which is contrary to and/or nullifies/voids in any way such
member/partner protective provisions in the event of any actual or alleged
breach of the lease by the Landlord, the sole remedy shall be against the assets
of the Landlord and no individual member, partner or other associated entity of
the company shall be liable for any damages arising from any act or omission or
neglect including negligence of the Owner or of any other Tenant as well as any
other Tenant's employees, agents, invitees, customers, contractors or any other
person in or about the property, including but limited to a vandal.

Further, Tenant expressly agrees to indemnify, hold harmless and defend
Landlord, any owner of Landlord, such as any shareholder or L.L.C. member as
well as any employee, contractor or other agent of Landlord from claim or
losses, damages or the like, including costs attorney's fees, arising out of all
enumerated causes including but not limited to Tenant's utilization of the
leased premises. All such continuing agreements duties and promises of Tenant
contained in this exemption of Landlord from liability as well as such
continuing duties, obligations and promises of Tenant contained elsewhere in
this agreement shall survive and continue following the end of the lease term
and/or occupancy of Tenant with such indemnification, hold harmless and defend
provisions to apply to any claim, loss, damage, liability or the like made by
Tenant, invitee of Tenant, employee, contractor or other agent of Tenant or any
other third party, including but not limited to another Tenant and including any
and all claims even if caused by the negligence of the Landlord and any Owners
of Landlord and/or agent of Landlord including an employee or contractor of
Landlord.

     21.  LANDLORD'S CASUALTY INSURANCE. Tenant agrees not to do anything,
including, but not limited to, structural changes, which could jeopardize the
Landlord's insurance coverage, create additional risk, fail to comply with a
law, or regulation, or Landlord's insurance company's requirements or cause an
increase in Landlord's insurance premium.

Tenant, each successive month, shall pay the Landlord, in addition to the rent,
one-twelfth (1/12th) of the Landlord's cost of special form - all ask property
damage, liability and casualty insurance ("Property Casualty Insurance"). It
shall be compiled on a pro rata share of square footage per unit, if there are
multiple units. Tenants percentage of their space to total property is 47%.
Monthly Insurance cost to Tenant is Seventy Dollars and Fifty Cents ($70.50)

     22.  INSPECTIONS. The Landlord or his Agent is hereby granted the right and
privilege to inspect the property both inside and outside at any time during the
term of this Lease, between the hours of 10:00 A.M. and 4:00 P.M. Should any of
the leased property be damaged the Landlord shall have the right to demand that
such damage be repaired immediately and at the sole cost, expense and risk of
the Tenant.

     23.  FIRE OR EARTHQUAKE. If at any time during the Lease, the Leased
Premises shall be destroyed by fire, by the
<PAGE>

elements, by earthquake or any other casualty or be so damaged by fire, by the
elements, by earthquake, or any other casualty that, in the reasonable judgment
of Landlord's contractor, the Leased Premises cannot be repaired, rebuilt or
restored within Thirty (30) working days from the date of such damage, this
Lease may, at the option of either party, be terminated by delivering written
notice of termination not later than Thirty (30) days after the date of the
casualty, and rights hereunder shall cease and terminate and the Tenant shall be
entitled to be reimbursed for all rents paid in advance. The Tenant agrees to
give the Landlord access to the Leased Premises so that the necessary repairs,
rebuilding or restoration may be resumed without delay, subject to availability
of insurance proceeds and the ability to obtain necessary permits. It is further
understood and agreed that during the time or times that the Tenant may be
unable to occupy the Leased Premises for the reason above stated, rental shall
abate proportional to the square footage of the Premises which is unavailable
for occupancy, until said Leased Premises are again in condition to be available
for use by the Tenant.

     24.  LIGHTING AND OTHER FIXTURES. The Tenant agrees to furnish and install
at his own sole cost and risk upon, obtaining Landlord's prior written approval,
any additional lighting fixtures, cooling and heating system, needed for
Tenant's efficient operation(s). All said additions and/or alterations shall
become the property of the Landlord, without charge, at the termination of this
Lease.

     25.  BANKRUPTCY. It is hereby mutually agreed, covenanted and understood
that in the event the Tenant shall file a petition in bankruptcy or be
adjudicated a bankrupt, or make an assignment for the benefit of creditor or
take the benefit of any insolvent act or fail in business, then this Lease
shall, at the option of the Landlord, immediately terminate and in no event
shall this Lease be treated as an asset of the Tenant after the exercise of such
option.

     26.  WAIVER BY LANDLORD. The waiver by the Landlord of any breach or
breaches by the Tenant of any one or more of the covenants, agreements,
conditions, or obligations herein contained or the acceptance of any delinquent
payments shall not bar the Landlord's right to declare a forfeiture or to employ
any other rights or remedies of the Landlord in the event of any subsequent
breach of any such or other covenants, agreements, conditions or obligations.
Any entry and/or reentry by the Landlord, whether had or taken by the terms of
this Lease under what is generally known as summary proceedings, shall not be
deemed to absolve or discharge the Tenant from liability hereunder.

     27.  LEASE TRANSFER. The Tenant hereby agrees not to sell, transfer,
sublease, sublet or assign this Lease, or to lease or sublease the whole or any
portion of said Leased Premises without first obtaining the written consent of
the said Landlord, and any attempted assignment of lease or sublease without
such written consent shall be void. Even though the Landlord may give the
written consent to an assignment, subletting or transferring hereof, it is
agreed that no further assignment, subletting or transferring shall be made by
the Tenant without the express consent in writing by the Landlord. Such consent
cannot be unreasonably withheld. The Landlord reserves the right to assign this
Lease to anyone, and at any turn:, without given notice to the Tenant and
Landlord shall be released from all liability and obligation arising hereunder
after the date of such assignment.

     28.  REASONABLE CONSENT. As set forth in paragraph 27 above, Tenant shall
not sublet or assign the Leased Premises without the Landlord's prior written
consent, which consent shall not be unreasonably withheld In determining whether
to grant consent to the Tenant's sublet or assignment request, the Landlord may
consider any reasonable factor. Landlord and Tenant agree that any one of the
following factors, or any other reasonable factor, will be reasonable grounds
for deciding the Tenant's request:

     a.   financial strength of the proposed subtenant/assignee must be at least
equal to that of the existing Tenant;
<PAGE>

     b.   business reputation of the proposed subtenant/assignee must be in
accordance with generally acceptable commercial standards;

     c.   use of the Leased Premises by the proposed subtenant/assignee must be
identical to the use permitted by this lease;

     d.   percentage rents, if a condition of this Lease, of the proposed
subtenant/assignee, or the prospect of percentage rents, must be at least equal
to that of the existing Tenant;

     e.   managerial and operational skills of the proposed subtenant/assignee
must be the same or exceed those of the existing Tenant;

     f.   use of the Leased Premises by the proposed subtenant/assignee will not
violate or create any potential violation of any laws and;

     g.   use of the Leased Premises will not violate any other agreements
affecting the Leased Premises, the Landlord or other Tenants or require Landlord
to make alterations or improvements to the Premises.

     28.  TENANT CONTINUING RESPONSIBILITY. In the event the Landlord gives
consent to the Assignment of this Lease, the Tenant shall still nevertheless
continue to be fully liable and responsible for the full and faithful
performance of each and all of the terms, covenants and conditions herein
contained on the part of the Tenant herein to be performed and observed, and
provided further, that the Assignee shall likewise be deemed to have assumed the
full and faithful performance of said terms, covenants and conditions contained
within the Lease on the part of the Tenant herein to be performed and shall
deliver to the Landlord herein written assumption agreement assuming such
performance as aforesaid.

     29.  ENFORCEMENT OF LEASE. The said Landlord may, at his option, in
addition to any of the rights given by this indenture, enforce any provisions of
the laws of the State of Arizona, or of the United States of America governing
the relations of Landlord and Tenant, with the same effect as though the right
to enforce such provisions were herein specifically set forth. In the event any
provision in this Lease is held invalid by any court of competent jurisdiction,
the remaining provisions in this Lease shall be deemed severable and shall
remain in full force and effect.

     30.  CHANGE IN LEASE. The making, execution and delivery of this Lease has
not been induced by any representation, statement, warranties or agreements
other than those herein expressed. It is mutually agreed by and between the
parties hereto that this agreement supersedes all other previous and/or other
agreements bearing upon the above Leased Premises, and it is further agreed that
no changes to or in this Lease shall be made without being in writing, signed by
all of the parties hereto.

     31.  CONTINUING LEASE AFTER EXPIRATION. In the event that Tenant should
hold over and continue in the occupancy of the Leased Premises after the
expiration of the initial term of this Lease, or any extension thereof, with the
consent of the Landlord, express or implied, the Tenancy shall be deemed to a
tenancy only from month to month, upon the same terms and conditions as exist
and prevail at the time of the termination of the Lease, and subject to increase
in monthly rental at the option of the Landlord. Partial months shall be charged
as a full-month rent.
<PAGE>

     32.  SUIT TO ENFORCE TERMS OF LEASE. In the event of legal action between
any of the signatories to this Agreement to enforce the terms hereof the
prevailing party shall be entitled to reasonable attorneys' fees and court costs
from the party adjudged against.

     33.  POSSESSION AT EXPIRATION OF THIS LEASE. The Tenant further covenants
and agrees with the Landlord that at the expiration of the term mentioned in
this Lease, peaceable possession of the Leased Premises shall be given to the
Landlord, the Leased Premises to be in as good condition as they now are, or as
when first occupied, the usual wear and tear, inevitable casualties and loss by
fire excepted. Transfer of Possession of Leased Premises is defined as when
Tenant returns all keys to Landlord or his agents after vacating Leased
Premises.

     34.  IF LANDLORD CANNOT DELIVER POSSESSION OF LEASED PREMISES. If Landlord,
for any reason, cannot deliver possession of the Leased Premises to Tenant at
the commencement of said term, this lease shall not be void or voidable, nor
shall Landlord be liable to Tenant for any loss or damage resulting therefrom;
but there shall be proportionate deduction of rent covering the period between
commencement of said term and the time when Landlord can deliver possession.

     35.  INDEPENDENT COVENANT FOR PAYMENT OF RENT. The covenant of the Tenant
to pay rent shall at all times be recognized as an independent covenant under
the terms of this Lease and shall in no way be construed to be dependent upon
any other clause, condition or covenant contained herein.

     36.  IF LEASED PREMISES ARE DESERTED BY TENANT. In the event the Leased
Premises shall be deserted or if the Tenant ceased to conduct business without
paying punctually the rent herein called for, then in addition to all other
rights and remedies of Landlord hereunder, at law and in equity, the Tenant
grants to the Landlord or his agent the right to take over possession of the
Leased Premises as agent for the Tenant and do whatever the Landlord deems best
to protect his interest so that the Landlord may obtain the balance of money due
under this Lease, and without the Landlord waiving or relinquishing any of his
rights mentioned in this Lease.

     37.  LANDLORD'S RIGHT TO PLACE "FOR SALE" OR "FOR LEASE" SIGN. The Tenant
hereby grants upon the Landlord or his Agent the right to place a "For Lease"
sign on or in the Leased Premises at any time the tenant vacates the Leased
Premises, at any time there is evidence that the Tenant has ceased to conduct
business in or on the Leased Premises, or within 60 days of the termination of
this lease. Tenant hereby grants the Landlord or his agent., the right to place
a "For Sale" sign at anytime.

     38.  REPAIRS OR REPLACEMENT IN EVENT OF THEFT OR VANDALISM. Notwithstanding
anything to the contrary herein contained, the Tenant agrees to repair or
replace, without delay and at his own sole cost, expense and risk any and all
portions of the Leased Premises that may be damaged by theft, burglary,
vandalism or by malicious mischief.

     39.  RETROACTIVE RENT CLAUSE. Should landlord fail to notify Tenant of his
intent to revise the rental at such time or times as herein specified, such
rental shall continue to be subject to revision upon notification by Landlord as
provided herein and, when so revised, shall be retroactive to the date such
rental should have become effective, regardless of the number of years involved.

     40.  BROKERAGE FEE. David Nichols Realty, Inc and Weststar Mortgage Corp.
shall be recognized as the sole procuring broker for the Lease, or any option,
renewal, extension, addition, or enlargement thereof, or any sale or Lease of
this property, or any portion thereof, to the lessee, regardless
<PAGE>

of whether the terms of this Lease are modified or if the Lease is canceled and
a new Lease entered into. David Nichols Realty, inc. shall be entitled to 6% of
the gross Lease amount as commission, payable by Owner upon the signing of the
Lease, the signing of any renewal or extension, and/or the signing of any new
Lease with the lessee. David Nichols Realty, inc. shall also be entitled to 6%
of the gross sales amount as commission, payable by Owner upon the closing of
any sale of Leased Premises procured by Agent The minimum leasing commission
payable for any Lease is $500.00. This provision applies to, inures to the
benefit of, and binds all parties hereto, their heirs, legatees, devisees,
administrations, executors, successors, and assigns. If David Nichols Realty,
inc. must file an action against any person or entity to enforce the terms of
this brokerage provision, David Nichols Realty, inc., shall be entitled to
recover reasonable attorneys fees and court costs. The undersigned certify: that
they are the legal Owners of the described property, or are the authorized
agent(s) of the legal Owners.

In the event the Tenant requests and receives an assignment of this Lease, the
Agent or Broker shall be entitled to a brokerage fee for any remaining or any
additional term(s). The brokerage fee shall be paid by the Tenant, subject to
all of the above provisions.

     41.  SUBMISSION OF LEASE. Submission of this Lease for examination does
not constitute a reservation of or option for the Leased Premises. This
instrument becomes effective as a Lease upon execution and payment of Security
Deposit and prepaid rent for the four (4) months by Tenant and lease executed by
Landlord.

     42.  GENDER It is further understood that if more than one join in the
execution hereof or may be of the feminine, masculine or neuter gender, the
pronouns and relative words herein used shall be read and understood as if
written in plural, feminine, masculine or neuter, respectively.

     43.  SIDE HEADINGS. The herein side headings are for convenience only, and
do not define, limit or construe the content, of the various articles in this
Agreement"

     44.  MORTGAGE. The Tenant's rights under this Lease are and shall always
be subordinate to the lien of any existing mortgage or mortgages and to any
mortgage or mortgages which the Landlord may and shall have the right to execute
at any time during the term of the Lease or any renewal or extension thereof;
and the Tenant upon request by the Landlord agrees to execute within fifteen
(15) days of request such instrument or instruments permitting a mortgage or
mortgages to be placed upon the Leased Premises so as to subordinate this Lease
to any mortgage or mortgages.

     45.  SIGNS. The Tenant agrees not to place any permanent signs on the
windows, doors or walls or in any other locations on the Leased Premises without
first obtaining the written consent of the Landlord. The Tenant agrees not to
paint, inscribe or erect any outside signs on walls or roofs without first
obtaining the written consent of the Landlord; and should the Landlord give such
written consent, then all such signs and paint shall be removed by the Tenant at
least thirty days prior to the expiration of this Lease, and the walls, roof,
front and tear yards left in good condition, and free from any holes or damage.
Tenant is aware that there is a sign permit fee that is at Tenant's cost.
Landlord shall not withhold reasonable consent, except that Tenant must install
any City approved sign within the space provided for signs and Tenant shall be
solely responsible for obtaining all necessary approvals.

     46.  KEEPING LEASED PREMISES CLEAN. The Tenant agrees to keep the Leased
Premises inside and outside clean acrid neat at all times, including sidewalks,
windows, parking area and front and rear yards; and to keep sidewalk free of any
obstruction. Tenant shall be solely responsible for prompt removal and proper
disposal of all trash and garbage, and all removal of graffiti.
<PAGE>

     47.  NON-PAYMENT OF RENT. The Tenant further agrees with the Landlord that
upon the non-payment of the whole or any part of the rent or other amounts
payable hereunder at the time when same is above promised to be paid by the said
Tenant and said non-payment of rent continues for a period of ten (10) days,
after written notice from Landlord, or in the event said Leased Premises or part
thereof shall be deserted (which shall mean Tenant's failure to conduct business
in the Premises thirty (30) consecutive days or more without prior notice to
Landlord) during said term or of the breach of any of the other terms, covenants
or agreements herein contained, for which a specific performance is not
provided, which is not cured within thirty (30) days after written notice from
the Landlord, the Landlord may at his election, without notice or demand,
exercise any remedy available at law or in equity including without limitation
any one or more of the following: declare this Lease to be at an end and recover
said Leased Premises and recover such damages as he may have sustained; or he
may without notice or demand and without declaring the Lease ended, reenter and
occupy, remodel or refer the whole or any part of the Premises for the account
of Tenant on such terms and conditions as Landlord deems reasonable, or to
thereafter terminate the Lease even though the Premises have been refer.

     48.  LANDLORD'S DAMAGES. In the event of any default by Tenant, Tenant
agrees to pap to Landlord all amounts necessary to compensate Landlord for all
damage caused by Tenant's failure to perform its obligations under this lease,
including but not limited to the cost of recovering possession of the Premises
(including attorney's fees), the cost of repairs, alterations, leasing
commissions and, all other expenses incurred in maintaining, preserving or
reletting the Premises to a new tenant. Landlord shall be entitled to recover
from Tenant the rent and other charges due and unpaid:, (I) at termination of
the Lease if the Lease is terminated; (ii') if the Lease is not terminated, as
they become due by bringing one or more actions from time to time; or (iii) the
difference between the rental, if any, received by Landlord under any reletting
of the Premises, and the rental to the charges which would have been paid over
the term but for Tenant's default, with present value based on a discount rate
of $%.

     49.  EQUIPMENT, ROOF, WALLS AND OTHER REPAIRS. The Landlord, at his own
expense, shall keep the roof and outside walls of the Leased Premises in good
repair during the term of this Lease.  Landlord agrees to pay for the Common
Area maintenance for the entire subject property. Landlord to maintain HVAC,
Roof, Plumbing, Pipes and Sewer. Air conditioning to be repaired in reasonable
time.

     50   FINANCIAL STATEMENT. If Landlord desires to finance or refinance the
Leased Premises, or any part thereof, Tenant hereby agrees to deliver to any
lender designated by Landlord such financial statements of Tenant as may be
reasonably required by such lender. Such statements shall include the past three
years' financial statements of Tenant. All such financial statements shall be
received by Landlord in confidence and shall be used only for the purposes
herein set forth.

     51.  DISCLAIMERS. The Landlord and Tenant herein agree that there were no
promises, inducements, representations or agreements in connection with this
Agreement except those specifically set forth in writing. In the event of legal
action between any of the signatories to this Agreement to enforce the terms
hereof the prevailing party shall be entitled to reasonable attorneys' fees and
court costs from the party adjudged against.

     52   TIME OF ESSENCE. Time is of the essence of this Lease and every term,
condition, covenant and provision.

     53   BINDING OF HEIRS, ETC. This Lease shall inure to the benefit of and be
binding upon the heirs, executors, administrators, successors and assigns of the
respective parties hereto; except that
<PAGE>

nothing in this paragraph contained shall authorize an assignment of the
interest of Tenant herein without the prior written consent of the Landlord.

     54.  TENANT IMPROVEMENTS. Tenant intends to make improvements to the Leased
Premises after Lease execution. All such improvements shall be performed at
Tenant's sole cost pursuant to plans and specifications approved in writing by
Landlord prior to the commencement of any work. Landlord may grant or withhold
its consent to structural alterations or improvements in Landlord's sole
discretion.

     55.  NOT USED

     56.  AMERICANS WITH DISABILITIES ACT. Tenant shall, at its sole expense,
comply promptly with all applicable statutes, ordinances, rules, regulations,
orders and requirements in effect during the Term or any pact of the Term hereof
regulating the Leased Premises or the use thereof by Tenant. Tenant hereby
covenants that it shall, at its expense, comply promptly with all applicable
provisions of Title III of the Americans' With Disabilities Act, 42 U.S.C. (S)
12181 et se ., and all regulations promulgated thereunder (the "ADA"). Tenant
shall not use or permit the use of the Leased Premises in any manner that will
tend to create waste or a nuisance or which shall tend to disturb occupants of
buildings adjacent to the Premises. Neither Tenant nor its employees, customers
or any person for whom Tenant is responsible shall in any way obstruct or
interfere with the use of any street, sidewalk or passageway in or adjacent to
the Building.

     57.  CONDITION OF LEASED PREMISES. Tenant has had an opportunity to
thoroughly inspect the Leased Premises prior to the date of the signing of this
Lease, therefore, Tenant hereby accepts the Leased Premises "AS IS" in its
condition existing as of the date of the signing of this Lease, without any
representation or warranty, express or implied, oral or written, concerning the
condition, useability, or habitability of the Leased Premises, subject to all
applicable zoning, municipal, county, state and federal laws, ordinances and
regulations governing the regulating the use of the Leased Premises; and Tenant
hereby accepts this Lease subject thereto and all matters disclosed thereby and
by any exhibit; attached hereto, except that (I) heating, cooling and plumbing
systems shall be in operable working condition and (ii) the exterior roof shall
be water tight, as of the date of the signing of this Lease. Tenant acknowledges
that neither Landlord nor Landlord's agent has trade any representation or
warranty as to the suitability of the Leased Premises for the conduct of
Tenant's business. Tenant's singing of this Lease indicates his approval and it
will be presumed that the Leased Premises are satisfactory and the Lease shall
remain in full force and effect as if Tenant had given Landlord notification
that the Leased Premises are suitable for Tenant's business needs.

     58.  HAZARDOUS WASTE. Tenant shall not use, release, produce, dispose,
transport, treat or store in, on, under, or about the Leased Premises any
hazardous waste or toxic substance which is subject to: a) regulation under the
Arizona Hazardous Waste Management Act, A.R.S. 536-2821 et seq.; b) the Resource
Conservation and Recovery Act, 42 U.S.C. 6901 et seq., or c) regulation under
the Toxic Substance Control Act, 15 U.S.C. (S)2601 et seq; or (d) regulation by
any other federal, state, city, county or other statute, governmental
requirement, or authority..

     No activity may occur on the Leased Premises which could have toxic
results. The Leased Premises may be used for the production, treatment,
collection, storage, or disposal of any refuse, objectionable waste or any
material; a) in any manner inconsistent with the regulations issued by the
Arizona Department of Health Services, ACR R9-8-401, et seq.; b) so as to
require a permit or approval from the Arizona Department of Health Services,
pursuant to ACR R9-8-401 et seq., or c) in a manner
<PAGE>

which would cause the County Department of Health Services to inspect the Leased
Premises or issue orders pursuant to Chapter II of the County Health Code.

     Tenant hereby agrees to indemnify, defend, and hold harmless Landlord for
its failure by reason of any breach of this covenant, including any and all
costs, fees; penalties and any other liabilities incurred by Landlord resulting
from such violation of this covenant. In addition to any other rights and
remedies, Landlord may require Tenant to, immediately upon demand, abate any
release of hazardous materials using licensed contractors approved by Landlord,
or Landlord may without notice cause the work to be performed on behalf of
Tenant. Tenant shall pay all costs associated with abatement, remediation or
government enforcement actions arising from Tenant's breach of the foregoing
covenant. Tenant shall give Landlord immediate notice of the release of any
hazardous materials in or about the Premises, and of Tenant's receipt of any
notice or communication from any government authority or other person concerning
compliance of the Premises with any law or regulation relating to health, safety
or the environment ("Environmental Law"), or of the discovery of any condition
which violates or may violate Environmental Law.

     59.  CONDEMNATION. In the event of any condemnation or taking under the
exercise of the power of eminent domain ("Taking") of all or a portion of the
Leased Premises, Landlord shall be entitled to receive the entire award in any
such proceeding, including any award trade for the value of the estate vested by
this Lease in Tenant, and Tenant hereby expressly assigns to Landlord any and
all right, title and interest of Tenant now or hereafter arising in or to any
such award or any part thereof, except for any separate award payable to Tenant
for loss or damage to Tenant's trade fixtures, removable personal property, and
relocation costs. If the entire Leased Premises shall be Taken, then this Lease
shall automatically terminate as of the date Tenant is required by the
condemning agency to vacate the Leased Premises, and all rent and other charges
shall be paid through such date.  If a portion of the Leased Premises shall be
Taken and the use thereof is materially impaired thereby, then either Landlord
or Tenant shall have the right to terminate this Lease as of the date Tenant is
required to vacate such portion of the Leased Premises ("Taking Date") upon
giving the other notice of such election not later than thirty (30) days from
the Taking Date. All rent and other charges shall be paid through the Taking
Date. If the use of the Leased Premises is not materially impaired by the
Taking, or if materially impaired but neither landlord nor Tenant terminates
this Lease, then either such event this Lease shall continue in full force and
effect with respect to the remainder of the Premises except that, as of the
Taking Date, base rent shall be reduced by an amount which is equal to the
proportion thereof that the area taken bears to the entire area of the Leased
Premises before the Taking, and Landlord shall, at its cost and expense, to the
extent practicable restore, the Leased Premises on the land remaining to a
complete unit of like quality and character as existed prior to such Taking.

     60.  NOTICES. All notices or other documents which either party hereto is
required or may desire to give to the other shall be in writing and may be given
by delivering the same personally or by sending the same by certified or
registered mail, postage prepaid, to the addresses which are written below the
signatures of the entities or to such other place as may from time to time be
designated by a written notice. Any notice or other document mailed as aforesaid
shall be deemed sufficiently served or given at the time of mailing thereof.

     61.  LANDLORD'S DEFAULT. Except as otherwise provided in this Lease,
landlord shall be in default under this Lease if landlord fails to perform its
obligations hereunder and said failure continues for thirty (30) days after
written notice from Tenant to Landlord, or if such failure cannot reasonably be
cured within thirty (30) days, if Landlord fails to commence cure within thirty
(30) days and continues diligently to pursue the curing of the same. Landlord's
liability shall in no event exceed the value of Landlord's interest in the
Premises as the same may be encumbered.
<PAGE>

     62.  WARRNTY OF AUTHORITY. The person signing this Lease represents and
warrants that he has authority to do so and that tenant is a duly qualified
corporation.

     63.  FORCE MAJEURE.  Any prevention, delay or stoppage due to strikes,
lockouts, labor disputes, acts of God, inability to obtain labor or materials or
reasonable substitutes therefor, governmental restrictions, governmental
regulations, governmental controls, enemy or hostile governmental action, civil
commotion, fire or other casualty, and other causes beyond the control of the
party obligated to perform shall excuse the performance by such party of a
period equal to any such prevention, delay or stoppage, except the obligations
imposed with regard to rental and other monies to be paid by tenant pursuant to
this Lease.

     IN WITNESS WHEREOF, the said parties to those presents have hereunto set
their hands the day and year first above written.

TENANT:                            LANDLORD:
Chorum Technologies, Inc           Larry Michael Sandusky &
                                   Rebecca Anne Sandusky
By: /s/ Bob Trecartin              By:___________________
   --------------------------
     Authorized Officer            By:___________________
<PAGE>

                      FIRST AMENDMENT TO COMMERCIAL LEASE

THIS FIRST AMENDMEIN"I' TO LEASE (this "Amendment") dated as of July 12th, 2000
is entered into between Larry Michael Sandusky & Rebecca Anne Sandusky
("Landlord") and Chorum Technologies, Inc ("Tenant") and David Nichols Realty,
Inc., ("Agent").

                                   RECITALS

     A.   Landlord and Tenant are parties to that certain Commercial Lease
Agreement dated July 12th, 2000 (the "Lease"), pursuant to which Landlord leased
to Tenant approximately 6,576 square feet of space known as 211 E. 6th Street,
in the County of Pima, City of Tucson, State of Arizona, as more particularly
described in the Lease.

     B.   The parties desire to extend the term of the Lease and to amend and
modify the terms and conditions of the Lease as set forth below.

     NOW, THEREFORE, in consideration of the mutual covenants and promises of
the parties, the receipt and adequacy of which are hereby acknowledged, the
parties hereto agree as follows:

     1.   Leased Premises. Section 1 of the Lease is amended to add at the end
of the section. "The Leased Premises consists of approximately 6,576 square feet
of space."

     2.   Use of the Leased Premise. Section 2 of the Lease is amended to add at
the end of the section "and any other use permitted by law."

     3.   Compliance with Laws. Section 4 of the Lease is amended to add in the
fourth line of the second paragraph after "Premises and the" and before "use
thereof", the following: "Tenant's particular".

     4.   Conduct of Business. Section 5 of the Lease is amended to add at the
end of the section the following: "Notwithstanding the foregoing, Tenant may
vacate the Leased Premises so long as Tenant continues to pay Rent and other
sums due and payable under the Lease and performs all other obligations under
the Terns of the Lease."

     5.   Term. Section 6 of the Lease is amended to extend the term of the
lease through the 8th of October, 2002.

     6.   Rent. Section 7 of the Lease is amended to add at the end of the
section the following:

          for the period from June 3, 2000 up to and including October 8, 2000,
          which Landlord hereby acknowledges receipt. From and after October 9,
          2000, Tenant shall pay to Landlord each month in advance, during the
          term of this Lease, rent in the amount of:

Rental Period                           Monthly Rent

October 9, 2000 - October 8, 2001       $6,576.00
October 9, 2001 - October 8, 2002       $6,850.00
<PAGE>

Rent for partial months of this Lease shall be prorated. The lease remains a
net, net, net lease.

7.   Alterations and Additions. Section 14 of the Lease is amended to add at the
end of the section the following:

Notwithstanding the foregoing, Landlords consent to any request by Tenant for
any alteration, additions or improvements to the Leased Premises shall not be
unreasonably withheld or delayed. Landlord shall, at the time of granting its
consent to any alteration, addition or improvement, shall designate, if
requested by Tenant, whether or not Landlord shall require such alteration,
addition or improvement to be removed at the end of the term as set forth in
this Section 14.

8.   Liens Created by Tenant. Section 15 of the Lease is amended so as to change
the reference in the fifth line of this section from "ten (10) days" to "thirty
(30) days".

9.   Liability Insurance. Section 19 of the Lease is amended so as to change the
reference in the fourteenth line of this section from "rated A+ or better" to
"rated A- or better".

10.  Exemption of Landlord from Liability. Section 20 of the Lease is amended to
add at the end of the second paragraph the following: "Nothing contained herein
shall limit Landlord's obligation to return the Security Deposit". Section 20 is
further amended to add at the end of the section: "Notwithstanding the
foregoing, the exemption from liability contained in this section shall not
apply to the negligence or willful misconduct of Landlord."

11.  Fire or Earthquake. Section 23 of the Lease is amended to replace the
reference to "Thirty (30) working days from the date of such damage," in the
fourth and fifth lines of this section to "Ninety (90) working days from the
date of such damage."

12.  Lease Transfer. Section 27 of the Lease is amended to delete the period at
the end of the last sentence of this section and to add the following: ",
provided Landlord also transfers the Security Deposit to such assignee."

13.  Reasonable Consent. Section 28 of the Lease is amended to delete in their
entirety subsections "a", "d" and "e".

14.  Mortgage. Section 14 of the Lease shall be deleted in its entirety and
replaced with:

Subordination; Sale.

(a)  Subordination. This Lease shall be subject and subordinate at all times to
the lien of all mortgages and deeds of trust securing any amount or amounts
whatsoever which may now exist or hereafter be placed on or against the Leased
Premises or on or against Landlord's interest or estate therein, all without the
necessity of having further instruments executed by Tenant to effect such
subordination. Notwithstanding the foregoing, in the event of a foreclosure of
any mortgage or deed of trust or of any other action or proceeding for the
enforcement thereof, or of any sale thereunder, this Lease; shall not be
terminated or extinguished, nor shall the rights and possession of Tenant
hereunder be disturbed, if Tenant is not in default under the terms of this
Lean, and Tenant shall attorn to the person who acquires Landlord's interest
hereunder through any such mortgage or deed of trust. Tenant agrees to execute,
acknowledge and deliver upon demand such further instruments evidencing such
subordination of this Lease to the Lien of all such mortgages or deed of trust.
Tenant agree; to execute, acknowledge and deliver upon demand such further
instruments evidencing such subordination of this Lease to the lien of all such
mortgages and
<PAGE>

deeds of trust as may reasonably be required by Landlord, but Tenant's covenant
to subordinate this Lease to mortgages or deeds of trust hereafter executed is
conditioned upon each such senior mortgage or deed of trust, or a separate
subordination agreement, containing the commitments specified in the preceding
sentence.

(b)  Sale. If the original Landlord hereunder, or any successor owner of the
Leased Premises, sells or conveys the Leased Premises, all liabilities and
obligations on the part of the original Landlord, or such successor owner, under
this Lease accruing after such sale or conveyance shall terminate and the
original Landlord, or such successor owner, shall automatically be released
therefrom, and thereupon, all such liabilities and obligations of the original
Landlord or such successor owner shall be binding on the new owner, the lease
shall remain in full force and effect, the Tenant shall not be otherwise
disturbed and the Tenant shall attorn to such new owner.

15.  Non-Payment of Rent. Section 47 of the Lease is amended so that the term
"deserted" shall mean Tenant's failure to conduct business in the Premises
thirty (30) consecutive days or more without prior notice to Landlord and
without payment of rent.

16.  Late Charges. If any installment of rent or any sum due from Tenant shall
not be received by Landlord or Landlord's designee within ten (10) days after
the date said rent is due, then Tenant shall pay to Landlord a. late charge
equal to ten percent (10%) of the amount due.

17.  Equipment, Roof, Walls and other Repairs. Section 49 of the Lease is
amended so as to delete the last sentence in this section to be replaced with
the following: "Landlord shall have the HVAC repaired and in proper working
order no later than August 1, 2000. Tenant will assume responsibility for HVAC
once satisfactory repair has been completed.

18.  Tenant Improvements. Section 54 of the Lease is amended to add at the end
of this section the following: "For all other alterations and improvements, the
provisions of Section 14 of the Lease, as amended herein, shah apply."

19.  Americans with Disabilities Act. Section 56 of the Lease is amended to
insert in the fourth line of this section after "Premises or the" and before
"use thereof by Tenant" the following: "Tenant's particular". Section 56 d'
further amended to delete the period at the end of the second sentence and to
add the following: "arising out of Tenant's particular use of the Leased
Premises."

20.  Additional Provisions. The Lease is hereby amended by adding the following
sections:

(a)  64. Parking. The Tenant shall have the right to the exclusive use of twelve
(12) parking spaces in the rear of the building, during the term of this Lease.

(b)  65. Signage. The Landlord reserves the right to place reasonable signage on
6/th/ Street, subject to Tenants prior written consent, which shall not be
unreasonably withheld.

(c)  66. Dumpster Charges. The Dumpster charges for the removal of waste
material will be divided equally between the Landlord and the Tenant during the
term of this Lease.

(d)  67. Additional Brokerage Fee. Any additional brokerage fee as a result of
this Amendment or the exercise of Duly option shall be pursuant to a separate
agreement and shall be paid by Landlord.
<PAGE>

(e)  68. Option to Renew. Landlord grants Tenant one (1) option to renew this
lease for a period of two (2) years, provided Tenant provides Landlord with
written notice not less than sixty (60) days prior to the termination of this
Lease. All of the terms and conditions contained in the Lease, as amended, shall
apply during any option period with the exception of rent which shall be as
follows:

Rental Period                           Monthly Rent
October 9, 2002 - October 8, 2003       $7,124.00
October 9, 2003 - October 8, 2004       $7,398.00

21.  Except as set forth therein, the Lease remains unmodified and in full force
and effect. In the event of any inconsistency between the provisions of the
Lease and this Amendment, the terms of this Amendment shall control.

22.  This Amendment may be executed in two or more counterparts, which when
taken together shall constitute one and the same instrument. The parties also
agree and intend that a signature by facsimile machine shall find the party so
signing with the same effect as though the signature were an original
signature;.

IN WITNESS WHEREOF, Landlord and Tenant have executed and delivered this First
Amendment to Commercial Lease on the date first set forth above.

LANDLORD:                                    TENANT:

Larry Michael Sandusky & Rebecca Anne        Chorum Technologies, Inc.,
Sandusky,

By:  _________________________________       By:    /s/ Bob Trecartin
                                                  ------------------------------

Its: _________________________________       Its: ______________________________

AGENT:

David Nichols Realty, Inc.

By:  _________________________________

Its: _________________________________

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