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                                                                    EXHIBIT 10.1



                                Amendment No. 3
                                       to
                             Procurement Agreement


This Amendment ("Amendment") is made and entered into effective this 9th day of
January, 2001, by and between WILLIAMS COMMUNICATIONS, LLC ("Williams") and
CORVIS CORPORATION ("Corvis").

                                  -WITNESSETH-

WHEREAS, Williams and Corvis are parties to that certain Procurement Agreement
which is dated April 6, 2000, and which has been subsequently amended by
amendments dated May 3, 2000, and June 23, 2000, (the "Agreement"); and

WHEREAS, Williams and Corvis desire to further amend the Agreement.

NOW, THEREFORE in consideration of the foregoing premises and mutual promises
and covenants of the parties hereto, the receipt and sufficiency of which is
hereby acknowledged, Williams and Corvis agree to amend the Agreement as
follows:

1.   Sections 3.1 and 3.2 shall be deleted in their entirety and replaced with
the following:

          "3.1 Purchase Commitments.  Following Customer's notice of a
          successful completion of the Field Trial, Customer will purchase for
          its own use or for resale to others, subject to the terms and
          conditions of this Agreement, from Corvis, during the Initial Term,
          Corvis Equipment, Software and Services in quantities and in
          configurations priced at Three Hundred Million dollars ($300,000,000)
          ("Minimum Purchase Commitment"), based on the prices and license fees
          set forth in Attachment 6. It is acknowledged that Customer may elect
          to purchase Corvis Equipment, Software and/or Services in quantities
          in excess of the foregoing commitment.  Amounts paid by Customer under
          the Field Trial Agreement, if any, shall be deemed purchases that
          apply to the Minimum Purchase Commitment.

          3.2 (a) Initial Purchase Commitments.  Customer hereby commits to
          purchase from Corvis, and Corvis commits to sell to Customer, the
          Corvis Equipment, Software and Services described in clauses (i) and
          (ii) of this Section 3.2(a) at the times and on the terms indicated
          below and such commitment shall be deemed to be, and have the same
          force and effect of, a Purchase Order for such Equipment, Software and
          Services:

               (i) Customer will purchase Equipment and Software in the amount
          of $60,045,570 with $18,134,100 of such amount being comprised of the
          purchase price for the Field Trial Equipment and Software (including
          license fees therefore) and the remaining $41,911,470 being the
          purchase price for the Equipment, Software and Services (including
          license fees therefore) set forth in Attachment 3.2(i) and being for
          the route from [*]. Upon Customer's issuance of notice of a successful
          completion of the Field Trial, the Field Trial Equipment and Software
          will deemed to have been delivered to the Customer and Customer shall
          pay the $18,134,100 for such items within thirty days of such notice
          and pursuant to an invoice therefore to be submitted by Corvis. It is
          acknowledged that the purchase described in this clause 3.2 (a)(i)
          with respect to the Field Trial Equipment and Software shall satisfy
          the Customer's obligations to purchase the Field Trial Equipment and
          Software pursuant to Paragraph 2 of the Field Trial Agreement. All of
          the
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          Equipment, Software and Services (including license fees therefore)
          set forth in Attachment 3.2(a)(i) and being for the route from [*]
          shall be delivered to Customer no later than June 1, 2001, with
          delivery of such Equipment, Software and Services to be on the dates
          specified, and at the destinations designated, by Customer and
          otherwise in accordance with the terms of this Agreement. Delivery of
          such Equipment, Software and Services may not be delayed beyond June
          1, 2001. Invoicing and payment for such Equipment and Software shall
          be in accordance with the terms of this Agreement as modified by
          Attachment 3.2.

               (ii) Customer will purchase Equipment, Software and Services in
          the amount of at least $25 million which shall be comprised, at least
          in part, of that certain Equipment and Software identified in
          Attachment 3.2(a)(ii) as being for deployment on the [*].  The
          purchase prices for the Equipment, Software and Services to be
          purchased under this clause 3.2(a)(ii) shall be as set forth in
          Attachment 3.2(a)(ii).  All the Equipment, Software and Services
          purchased under this clause 3.2(a)(ii) shall be delivered to the
          Customer no later than December 1, 2001, with the delivery of such
          Equipment, Software and Services to be on the dates specified, and at
          the destinations designated, by the Customer and otherwise in
          accordance with the terms of this Agreement. Delivery of the Equipment
          and Software identified in Attachment 3.2(a)(ii) may not be delayed
          beyond December 1, 2001. Invoicing and payment for such Equipment and
          Software shall be in accordance with the terms of this Agreement as
          modified by Attachment 3.2.

     (b) Because of the rapid pace of change in technology in the area of
     telecommunications equipment and the uncertainty as to the exact nature of
     Customer's future system needs, it is agreed that, notwithstanding any
     other provision of this Agreement, including, among others, Section 3.1,
     Customer shall have no binding obligation to purchase Corvis Equipment,
     Software and Services beyond those amounts specified in paragraph 3.2 (a)
     above, and Customer shall have no liability to Corvis with respect to, or
     arising from, Customer's failure, for any reason, to make any purchases
     under this Agreement beyond those set forth in paragraph 3.2 (a) above,
     provided, however, that failure to fulfill binding forecasts issued by
     Customer pursuant to Section 3.3 shall have the results specified in
     Sections 3.3 and 3.4 and that Purchase Orders shall constitute binding
     commitments.

     (c) All purchases made pursuant to this Section 3.2 (including those
     related to the purchase of the Field Trial Equipment and Software) shall
     constitute purchases which apply to the Customer's Minimum Purchase
     Commitment.

     (d) Customer shall not be required to include in any of the forecasts
     required under this Agreement any of those items to be purchased under this
     Section 3.2.

     (e) Corvis' warrants that it has completed and has in inventory substantial
     portions of the  items to be purchased by the Customer under this Section
     3.2 and such items are currently available for immediate shipment to
     Customer and agrees that any late delivery of any of the items covered by
     this Section 3.2 shall be subject to the provisions of Section 3.6.

2.   The following language shall be deleted from Section 3.3(b): "but at a
minimum the mutually agreed forecast will consist of amounts that will enable
Customer to meet its Initial Minimum Purchase Commitment".  In addition, the
phrase "Initial Minimum Purchase Commitment Period" in the final sentence of
Section 3.3 (b) shall be deleted and replaced with the phrase "Initial Term".  A
new clause (c) shall be added to Section 3.3 and shall provide that: "(c) It is
understood that Customer may forecast an amount of "zero" for any or all of the
months covered by any Forecast called for under this Agreement."

3.   Section 3.6 shall be deleted and amended to read in its entirety as
follows:

               (a) If Corvis does not deliver a Product within sixty (60) days
          after the delivery date for such Product as specified in a Purchase
          Order issued and accepted in accordance with Section

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          3.9 of this Agreement or as specified by Customer under Section 3.2,
          Customer may at any time thereafter cancel that portion of the
          Purchase Order that relates to any such Product not delivered within
          such sixty (60) day period and have the price and/or license fee
          applicable to such undelivered portion of such Purchase Order count
          toward the Minimum Purchase Commitment. In addition, Customer shall be
          entitled to a reduction in the purchase price for any late delivered
          Product that Customer is obligated to purchase pursuant to Section
          3.2, such reduction to be a percentage of the purchase price of the
          late delivered Product based upon the number of days such delivery is
          late as calculated in accordance with the following schedule:

<TABLE>
<CAPTION>
               Week #   Days Late  Price Reduction
               <S>      <C>        <C>
                1           0-7          [*]%
                2           8-14         [*]%
                3          15-21         [*]%
                4          22-28         [*]%
                5          29-35         [*]%
                6          36-42         [*]%
                7          43-49         [*]%
                8          50-56         [*]%
                9          57-63         [*]%
                10         64-70         [*]%
                11         71-77         [*]%
                12        Over 77        [*]%
</TABLE>

          This Section 3.6(a) will not apply to any failure by Corvis to meet
     its delivery obligations due to fault of Customer or due to events of Force
     Majeure, as provided in Article 10.

          (b) Except as otherwise agreed pursuant to an RFQ process or
     otherwise, for Purchase Orders issued (other than for Products Customer is
     obligated to purchase pursuant to Section 3.2) for calendar months
     occurring after the three calendar month period immediately following the
     calendar month in which the Initial Rolling Forecast was mutually agreed
     upon, if Corvis does not deliver a Product within sixty (60) days after the
     delivery date for such Product as set forth in a Purchase Order issued in
     accordance with this Agreement, Customer shall receive a Product purchase
     credit equal to 1% of the price and/or license fee for any such undelivered
     Product, for each additional 30-day period beyond the initial sixty (60)-
     day delay that Corvis continues to not meet its delivery obligations with
     respect to such Product.  For Purchase Orders issued for calendar months
     occurring after the six calendar month period immediately following the
     calendar month in which the Initial Rolling Forecast was mutually agreed
     upon, if Corvis does not deliver any Product within sixty (60) days after
     the delivery date for such Product, as specified in a Purchase Order issued
     and accepted in accordance with Section 3.9 of this Agreement, the Product
     purchase credit for late delivery shall be increased to 2% of the price of
     the undelivered Product for each additional thirty (30)-day period beyond
     the initial sixty (60)-day delay that Corvis continues to not meet its
     delivery obligations with respect to such Product.  In no event will
     product credits earned under this Section 3.6(b) with respect to any
     specific Product that is delivered late exceed twelve percent (12%) of the
     price and/or license fees for

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     such Products. Credits accrued pursuant to this Section 3.6(b) will
     automatically expire if not used within six (6) calendar months after the
     date of accrual. Product credits shall no longer accrue with respect to
     Purchase Orders that have been cancelled by Customer under this Section
     3.6(b). This Section 3.6(b) will not apply to any failure to meet Corvis
     delivery obligations due to fault of Customer or due to events of Force
     Majeure, as provided in Article 10.

4.   Section 3.11 of the Agreement shall be modified by changing the date in the
second sentence from "[*]" [sic] to "[*]".

5.   There shall be added at the end of Attachment 5 the following new
paragraph:

          "C. Joint Marketing Arrangement

          In addition to the foregoing provisions of this Attachment 5, Corvis
          and Customer shall establish a joint marketing/training fund to which
          Corvis will contribute an amount equal to three percent (3%) of the
          amounts paid by Customer to Corvis, from time to time, under this
          Agreement for the purchase of Corvis Equipment, Software and Services.
          This joint marketing/training fund may be used by Customer, at any
          time and at Customer's sole discretion, to (a) purchase training from
          Corvis  or cover the cost of training provided by Customer or third
          parties with respect to the Equipment and/or Software (not to exceed
          [*]% of the then unused amount of joint marketing/training fund);
          and/or (b) engage in joint marketing activities which Customer
          determines after consultation with Corvis will benefit both Customer
          and Corvis.  The amounts represented  by this three percent (3%) will
          be consumed by Customer either having Corvis (i) apply a portion of
          the joint marketing/training fund to any invoice for Corvis' training;
          (ii) reimburse Customer for expenses incurred by Customer in
          conducting, or having a third party conduct, training with respect to
          the Equipment and/or Software; and/or (ii) pay directly, or reimburse
          Customer for payment, to any third party vendor selected by Customer
          to perform services in conjunction with marketing activities which
          Customer determines will benefit both Customer and Corvis.

6.   Attachment 6 shall be amended by adding between the schedule headed "Volume
Deployment Pricing Schedule" and the portion which follows the heading
"Preferred Customer Pricing", the following:

     Current RFQ Price
     -----------------

     Commencing with the "2001 Transport Request For Quote" released on November
     14, 2000, Customer shall, on a regular basis thereafter, issue to Corvis
     (and other of Customer's vendors) a request for quote ("RFQ").  As a result
     of each RFQ, Corvis will be expected to provide, among other things, price
     quotations for the Equipment, Software and Services.  Except for items
     Customer is obligated to purchase pursuant to Section 3.2, the price agreed
     to pursuant to any such RFQ shall apply in lieu of the price in the the
     "Volume Deployment Pricing Schedule" contained in Attachment 6.

7.   That portion of Attachment 6 which follows the heading "Preferred Customer
Pricing" is hereby deleted and replaced with the following:

In consideration of Customer's commitment to purchase from Corvis during the
Initial Term a total dollar value of Products equal to the Minimum Purchase
Commitment, Corvis agrees as follows:

(a)  If during the Initial Term Corvis sells and ships to any Third-party
     Corvis Customer Products at pricing lower than the Extended Pricing, then,
     for so long as Corvis continues to offer such lower pricing to such Third-
     party Corvis Customer, Corvis will establish a pool of credits ("Product
     Credits") based upon  the difference between the Extended Pricing for
     Products and the pricing offered to such Third-party Corvis Customer, The
     parties shall agree upon a method for determining whether pricing extended
     to Third-party

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     Corvis Customers is lower than that extended to Customer by developing two
     reference configurations models (one based upon a fully-loaded point-to-
     point configuration and the other based upon a fully-loaded optical network
     configuration utilizing one or more optical routers). The foregoing method
     shall provide that the adjusted Extended Pricing shall be the pricing that
     assures that for a purchase of Products comprising the applicable reference
     configuration model, the aggregate pricing of such Products to Customer and
     the Third-party Corvis Customer would be the same. Product Credits may be
     applied only toward the purchase of Products and maintenance or training,
     subject to the terms and conditions set forth herein. Product Credits will
     not be counted toward meeting the Minimum Purchase Commitment. Such Product
     Credits will be applied to Products shipped to Customer after the date on
     which Corvis first shipped to such Third-party Corvis Customer such
     Products at pricing lower than the Extended Pricing.

(b)  With respect to Products, Customer may apply the Product Credits it
     accumulates against orders placed before the termination or expiration of
     this Agreement up to twenty percent (20%) of the purchase price of Products
     ordered by Customer prior to the termination or expiration of this
     Agreement.

(c)  Definitions.
     -----------

          (i)  "Extended Pricing" means the prices and license fees for the
               Products set forth in this Attachment 6, as such prices and
               license fees may, from time to time, be adjusted in accordance
               with subsection (a) above.

          (ii) Third-party Corvis Customer" means any third party customer of
               Corvis (other than any wholly or partially owned subsidiary or
               affiliate of Corvis) but shall not include customers who are
               government entities or customers who are primarily acting as
               resellers of Corvis Products.  A party shall be deemed a Third-
               party Corvis Customer irrespective of the volume of purchases
               made by such entity.

8.   The first sentence of clause (a) of Section 6.3 shall be deleted in its
entirety and replaced with the following:

     (a) Except as otherwise provided in this Agreement or explicitly agreed in
     writing between the parties, Customer will remit payment to Corvis for
     invoiced amounts within thirty (30) days after Customer's receipt of the
     invoice, which will be issued upon shipment of the Product or completion of
     Services, as applicable.

9.   In the first sentence of the second paragraph of Section 7.1, the phrase
"24 month period" shall be deleted and replaced with the phrase "60-month
period".

10.  The final sentence of Section 7.1 shall be deleted and replaced with the
following:

"If Customer has available unused credits under Section 3.4 at the end of the
Initial Term and Corvis has given notice to terminate this Agreement, then
Customer shall have the right to extend the Term of this Agreement by an
additional twelve (12) months."

11.  Section 23.4 shall be modified by deleting the following language:

          "Customer's obligation to meet the Total Minimum Purchase Commitment
     will survive the expiration of this Agreement or the termination of this
     Agreement, by Corvis for cause pursuant to Section 23.1 or pursuant to
     Clause (iii) of Section 2.2.  Notwithstanding anything in this Agreement
     to the contrary, Customer shall in no event have any obligation for the
     Initial Minimum Purchase Commitment or the Total Minimum Purchase
     Commitment or any portion thereof in the event of termination by either
     party pursuant to Clause (i) of Section 2.2 or by Customer pursuant to
     Clause (ii) of Section 2.2 or Sections 10.4, 23.1, 23.2 or 23.3 or in the
     event this Agreement becomes null and void pursuant to Section 7.1."

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and replacing it with the following: "Customer's obligations with respect to the
Minimum Purchase Commitment shall not survive the expiration of this Agreement
or its termination for any reason."

12.  The definition "Initial Minimum Purchase Commitment", "Initial Minimum
Purchase Commitment Period", "Initial Minimum Purchase Commitment Shortfall",
"Total Minimum Purchase Commitment", "Total Minimum Purchase Commitment Period"
and "Total Minimum Purchase Commitment Shortfall" as set forth in Article 28
shall be deleted in their entirety.

13.  The System Specifications in Attachment 28 is hereby deemed modified (as of
the time and in the manner indicated) to include any modification to the System
Specification contained in the list of Critical Items agreed to between the
parties dated January 8, 2000 and initialed by the parties.

14.  Unless specifically indicated otherwise, all capitalized terms used herein
shall have the same meaning given to them in the Agreement

15.  Except as specifically amended herein, all terms, conditions and provisions
contained in the Agreement shall remain unchanged and in full force and effect.

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IN WITNESS WHEREOF, the parties have executed this Amendment on the day and year
first above set forth.

WILLIAMS COMMUNICATIONS, LLC           CORVIS CORPORATION

    /s/ Greg S. Floerke                      /s/ Rick Bakosh
----------------------------           -----------------------------
       (SIGNATURE)                             (SIGNATURE)

     Greg S. Floerke                           Rick Bakosh
----------------------------           -----------------------------
         (PRINT)                                 (PRINT)

   Senior Vice President                   Senior Vice President
----------------------------           -----------------------------
         (TITLE)                                 (TITLE)

[*] Confidential treatment requested.

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                                                                  Attachment 3.2



     For Corvis Equipment purchased pursuant Sections 3(a)(i) and 3(a)(ii) of
this Agreement (excluding any Field Trial Equipment), the normal payment terms
of the Agreement shall be modified as follows:

     Corvis shall invoice Customer upon shipment for only 50% of the purchase
price for Corvis optical network gateway common equipment, optical amplifiers,
and optical add/drop multiplexers ("Corvis Common Equipment"). Corvis Common
Equipment shall not include transmitters or receivers.  The remaining purchase
price will be due and payable (net 30 days) as follows:

          .    50% of the unpaid portion of the purchase price of the Corvis
               Common Equipment upon the earlier to occur of (i) utilization of
               50% of the transmission capacity on (or at either end of) any
               span on which the Corvis Common Equipment is deployed, or (ii) 9
               months after shipment turn up of the Corvis Common Equipment.

          .    The remaining unpaid balance of the purchase price of the Corvis
               Common Equipment upon the earlier to occur of (i) utilization of
               75% of the transmission capacity on (or at either end of) any
               span on which the Corvis Common Equipment is deployed, or (ii) 11
               months after shipment turn up of the Corvis Common Equipment.

     Utilization will be determined at true-up meetings and additional payments
will be payable immediately based on utilization thresholds mentioned above.  If
additional payments are due based upon elapse of time as opposed to utilization,
such payments are to be made immediately upon the lapse of the relevant time.
Corvis reserves the right to audit utilization.

     Initial order and "Standard Term Tx/Rx Cards" ordered are subject to normal
invoicing and payment terms as provided in this Agreement.  For each "Standard
Term Tx/Rx Card" order, Williams may order an additional quantity of up to 10%
of "Build Ahead Tx/Rx Cards" to be shipped and installed in the network span.
At 75% utilization on a given span, the build ahead card quantity will drop to
5%.  The "Build Ahead Tx/Rx Cards" will be separately invoiced at shipment on
net 180 Day payment terms and and must be either paid for or returned by such
date.  If any "Build Ahead Tx/Rx Card" pair is utilized, payment for all build-
ahead pairs in a span will be immediately due.

     All orders are subject to the agreed upon volume forecasting process.

[*] Confidential treatment requested.

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