<PAGE>

                                                                   EXHIBIT 10.50

          FIRST AMENDMENT TO REAL PROPERTY PURCHASE AND SALE AGREEMENT

         THIS FIRST AMENDMENT dated as of October 15, 2002 (this "Amendment") to
Real Property Purchase and Sale Agreement dated as of July 26, 2002 (the
"Agreement"), is entered into by and among Williams Headquarters Building
Company, a Delaware corporation ("Seller"), Williams Technology Center, LLC, a
Delaware limited liability company ("Purchaser"), Williams Communications, LLC,
a Delaware limited liability company ("WCL"), Williams Communications Group,
Inc., a Delaware corporation ("Communications"), Williams Aircraft Leasing, LLC,
a Delaware limited liability company ("WAL"), WilTel Communications Group, Inc.,
a Nevada corporation ("New WCG"), Williams Aircraft, Inc., a Delaware
corporation ("WAI") and CG Austria, Inc., a Delaware corporation ("CG Austria").
All capitalized terms not otherwise defined herein shall have the meanings given
to such terms in the Agreement (as amended by the Amendment).

         WHEREAS, the parties have agreed to modify the provisions relating to
the payment of the Purchase Price and certain other provisions of the Agreement
pursuant to the terms of this Amendment;

         WHEREAS, Communications and its subsidiary, CG Austria, Inc., a
Delaware corporation, filed voluntary petitions on April 22, 2002 for relief
pursuant to chapter 11 of title 11 of the United States Code, 11 U.S.C. Sections
101-1330 (as amended, the "Bankruptcy Code"), which cases are pending in the
United States Bankruptcy Court for the Southern District of New York (the
"Bankruptcy Court") and procedurally consolidated under Case No. 02-11957; and

         WHEREAS, pursuant to and in connection with the Second Amended Joint
Chapter 11 Plan of Reorganization of Communications and CG Austria, Inc., a
Delaware corporation ("CG Austria") dated August 12, 2002, filed with the U.S.
Bankruptcy Court for the Southern District of the State of New York (the "Plan")
and the Escrow Agreement (hereinafter defined), the parties hereto have
determined to amend the Agreement to consummate the Plan and the transactions
contemplated thereby and in connection therewith allow New WCG, the successor
entity to Communications created pursuant to and in accordance with the Plan,
and WAI to become parties to the Agreement.

         NOW, THEREFORE, in consideration of the foregoing premises and the
mutual promises and obligations contained herein, the receipt and sufficiency of
which are hereby acknowledged, the Parties hereto hereby agree as follows:

         1. Section 1.01 of the Agreement is hereby amended by deleting the
defined term "Purchase Money Note" set forth therein and substituting in lieu
thereof the defined term "Purchase Money Notes" as follows:



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<PAGE>

                  "Purchase Money Notes" shall mean the collective reference to
                  the Long Term Note and the Short Term Note, each of which
                  shall be secured by the Purchase Money Mortgage and the Pledge
                  Agreement.

         2. Section 1.01 of the Agreement is hereby amended by adding the
following defined terms thereto:

                  "Administrative Services Agreement" shall mean the Amended and
                  Restated Administrative Services Agreement dated as of April
                  23, 2001, between TWC and Communications, as amended,
                  restated, supplemented or otherwise modified from time to
                  time.

                  "Agreement for Resolution of Continuing Contract Disputes"
                  shall mean the Agreement for the Resolution of Continuing
                  Contract Disputes dated as of July 26, 2002, among TWC,
                  Communications and WCL, as amended, restated, supplemented or
                  otherwise modified from time to time.

                  "Aircraft Refinancing Net Cash Proceeds" shall have the
                  meaning specified in Section 2.08(b).

                  "Australian Legal Opinion" shall mean an opinion of
                  Atanaskovic Hartnell addressed to Seller and its successors
                  and assigns dated as of the Closing Date, opining as to the
                  enforceability of the Equitable Mortgage, the perfection of
                  the security interest granted thereby and such other matters
                  incident to the Transactions contemplated by the Equitable
                  Mortgage and the Pledge Agreement, which shall be in form and
                  substance reasonably satisfactory to Seller.

                  "Building Purchase Escrowee" means Lawyers Title Insurance
                  Corporation, acting in the capacity of title insurance company
                  pursuant to the Title Instruction Letter.

                  "Building Purchase Closing Documents" means the collective
                  reference to the Company Building Purchase Closing Documents
                  and the TWC Building Purchase Closing Documents.

                  "CG Austria" shall mean CG Austria, Inc., a Delaware
                  corporation.

                  "Company Building Purchase Closing Documents" shall have the
                  meaning specified in the Escrow Agreement.

                  "Equitable Mortgage" means that certain Second Equitable
                  Mortgage of Shares dated as of October 15, 2002, executed by
                  CG Austria in favor of Seller, as amended, restated,
                  supplemented or otherwise modified from time to time.

                  "Escrow Agent" shall mean The Bank of New York, a New York
                  banking corporation.



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                  "Escrow Agreement" shall mean the Escrow Agreement dated as of
                  October 15, 2002, among New WCG, TWC, Leucadia and the Escrow
                  Agent, as amended, restated, supplemented or otherwise
                  modified from time to time.

                  "Escrow Period" shall mean the period between (a) October 15,
                  2002 and (b) the earlier of (i) the Escrow Period Termination
                  Date or (ii) the Escrow Period Breakage Date.

                  "Escrow Period Breakage Date" shall mean any date on which the
                  Escrow Period terminates other than as a result of the
                  occurrence of an Escrow Period Termination Date.

                  "Escrow Period Purchase Agreement Default" shall mean the
                  occurrence and continuance of one or more of the following
                  during the Escrow Period (in each case taking into account any
                  grace period or grace periods specified in Section 7.07 (b) of
                  this Agreement (which shall be applicable in all respects
                  during the Escrow Period): (a) the breach or violation of any
                  representation or warranty under Article III of this
                  Agreement; (b) the breach of or violation of any covenant
                  under Article IV of this Agreement; or (c) the breach of any
                  term or provision specified in Section 5.03 of this Agreement.

                  "Escrow Period Differential" shall have the meaning specified
                  in Section 2.08 of this Agreement.

                  "Escrow Period Termination Date" shall mean the date on which
                  the Building Purchase Closing Documents are released by the
                  Escrow Agent pursuant to and in accordance with Section 4 of
                  the Escrow Agreement.

                  "Intercreditor Agreement (Mortgage)" shall mean that certain
                  Intercreditor and Subordination Agreement (Mortgaged Property)
                  dated as of October 15, 2002, by and between Seller and the
                  Bank Agent, as amended, restated, supplemented or otherwise
                  modified from time to time, relating to the Purchase Money
                  Mortgage.

                  "Intercreditor Agreement (Pledge Agreement)" shall mean that
                  certain Intercreditor and Subordination Agreement (PowerTel
                  Collateral) dated as of October 15, 2002, by and between
                  Seller and the Bank Agent, as amended, restated, supplemented
                  or otherwise modified from time to time, relating to the
                  Pledge Agreement, in the form attached hereto as Exhibit 8.

                  "Intercreditor Agreements" shall mean the collective reference
                  to the Intercreditor Agreement (Pledge Agreement) and the
                  Intercreditor Agreement (Mortgage).

                  "Jones Day Legal Opinion" shall mean an opinion of Jones, Day,
                  Reavis & Pogue reasonably satisfactory to Seller addressed to
                  Seller dated as of the Closing Date, opining as to the
                  organization and good standing of Purchaser, WCL and CG
                  Austria in the State of Delaware, authorization of the
                  execution, delivery and performance by Purchaser and WCL of
                  the Purchase Money Notes, authorization of the execution and
                  delivery by Purchaser of the Purchase Money Mortgage and
                  authorization



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                  of the execution and delivery by CG Austria of the Pledge
                  Agreement, and the execution and delivery of the Pledge
                  Agreement by, and the enforceability of the Pledge Agreement
                  against, CG Austria and such other matters incident to the
                  Transactions contemplated herein, which shall be in form and
                  substance reasonably satisfactory to Seller.

                  "Leucadia" shall mean Leucadia National Corporation, a New
                  York corporation.

                  "Loan Documents" shall have the meaning specified in the WCG
                  Bank Facility.

                  "Long Term Note" shall have the meaning provided in Section
                  2.02(b) of this Agreement.

                  "New WCG" shall mean WilTel Communications Group, Inc., a
                  Nevada corporation, the successor entity to Communications
                  created pursuant to the Plan.

                  "New WCG Legal Opinion" shall mean an opinion of Jones Vargas
                  addressed to Seller dated as of the Closing Date, opining as
                  to the incorporation, existence and good standing of New WCG
                  under the laws of the State of Nevada, authorization of the
                  execution and delivery by New WCG of the Purchase Money Notes,
                  and such other matters incident to the Transactions
                  contemplated herein, which shall be in form and substance
                  reasonably satisfactory to Seller.

                  "Plan" shall mean the Second Amended Joint Chapter 11 Plan of
                  Reorganization of Communications and CG Austria dated August
                  12, 2002, filed with the U.S. Bankruptcy Court for the
                  Southern District of the State of New York, as may be amended,
                  supplemented or otherwise modified from time to time.

                  "Pledge Agreement" shall mean that certain Pledge Agreement
                  dated as of October 15, 2002, made by CG Austria in favor of
                  Seller at Closing (as amended, restated, supplemented or
                  otherwise modified from time to time), including the
                  Acknowledgment, Consent and Agreement attached thereto, in
                  form attached hereto as Exhibit 9 pursuant to which (a) CG
                  Austria shall pledge and grant a security interest in all of
                  its right, title and interest in and to the Pledged Shares and
                  certain related collateral to Seller, in form and substance
                  mutually satisfactory to Purchaser and Seller, provided that
                  any such liens and security interest shall be expressly junior
                  and subordinate to the liens and security interests granted by
                  CG Austria to the Bank Agent pursuant to the terms thereof and
                  shall be subject to the Intercreditor Agreement (Pledge
                  Agreement); and (b) CG Austria shall agree to cause WCP to
                  amend its organizational documents or to enter into other
                  agreements and documents to make WCP a "special purpose
                  entity", the purpose and activities of which shall be limited
                  to owning the stock of PowerTel and to conduct activities
                  necessary or appropriate in connection with such ownership.

                  "Pledged Shares" shall mean 66% of the beneficial interests of
                  WCP.



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<PAGE>

                  "PowerTel" shall mean PowerTel Limited (f/k/a Spectrum Network
                  Systems Limited) (ACN 001 760 103), a corporation organized
                  and existing under the laws of Australia.

                  "Purchase Agreement" shall mean the Agreement of Purchase and
                  Sale dated as of September 13, 2001 among Williams Technology
                  Center, LLC, a Delaware limited liability company, as
                  "Seller", Williams Headquarters Building Company, a Delaware
                  corporation, as "Purchaser", and Williams Communications, LLC,
                  a Delaware limited liability company, as "Guarantor", as
                  amended, restated, supplemented or otherwise modified from
                  time to time.

                  "Sale Leaseback Default" shall mean the occurrence and
                  continuance of any "Event of Default" specified in the defined
                  term "Event of Default" (as such term is defined in the Master
                  Lease or in any Sale Leaseback Transaction Document or any
                  default or event of default under, or any breach or violation
                  of any term or provision of, any Sale Leaseback Transaction
                  Document (in each case after taking into account any
                  applicable grace period or grace periods).

                  "Sale Leaseback Transaction Documents" shall mean the Master
                  Lease and the Aircraft Dry Leases, as any of the foregoing may
                  have been amended, restated, supplemented or otherwise
                  modified through and including the Closing Date and as any of
                  the foregoing may be amended, restated, supplemented or
                  otherwise modified from time to time following the Closing
                  Date.

                  "Second Mortgage" shall mean that certain Second Mortgage,
                  Assignment of Leases and Rents, Security Agreement, Financing
                  Statement and Fixture Filing dated as of October 15, 2002,
                  made by Purchaser in favor of the Bank Agent for the benefit
                  of the Lenders, as amended, restated, supplemented or
                  otherwise modified from time to time, pursuant to which
                  Purchaser shall grant mortgage liens and security interests in
                  all of its right, title and interest in certain of the
                  Acquired Assets and related collateral to the Bank Agent for
                  the benefit of the Lenders, provided that any such liens and
                  security interest shall be expressly junior and subordinate to
                  the liens and security interests granted by Purchaser to the
                  Seller in the Mortgaged Property (as such term is defined in
                  the Purchase Money Mortgage) and related collateral pursuant
                  to the terms thereof and shall be subject to the Intercreditor
                  Agreement (Mortgage).

                  "Side Letter" means that certain Letter Agreement dated as of
                  October 15, 2002, among Seller, Purchaser, WCL and New WCG,
                  with respect to the Purchase Money Mortgage, in the form
                  attached hereto as Exhibit E.

                  "Termination Statements" shall mean UCC financing statement
                  amendments prepared for filing under the Uniform Commercial
                  Code of each jurisdiction as may be necessary to terminate the
                  security interests and liens in favor of Seller created
                  pursuant to and in accordance with the Master Lease.



                                      -5-
<PAGE>

                  "Title Instruction Letter" shall mean that Title Instruction
                  Letter dated as of October 15, 2002, issued to the Building
                  Purchase Escrowee, among Purchaser, Seller, Building Purchase
                  Escrowee and the Bank Agent, as amended, supplemented or
                  otherwise modified from time to time.

                  "Title Policies" shall have the meaning specified in the Title
                  Instruction Letter.

                  "TWC Building Purchase Closing Documents" shall have the
                  meaning specified in the Escrow Agreement.

                  "TWC Party" shall mean TWC, Seller, WAL, WAI and any of their
                  respective subsidiaries and Affiliates.

                  "WCG Party" shall mean New WCG, Communications, WCL, Purchaser
                  and any of their respective subsidiaries and Affiliates.

                  "Williams Aircraft Leasing Transfer Agreement" shall mean the
                  Membership Interest Purchase Agreement, between WAI, as
                  "Seller", and WCL, as "Purchaser", in the form attached hereto
                  as Exhibit F.

                  "Williams Aircraft Leasing Transfer Documents" shall mean the
                  Williams Aircraft Leasing Transfer Agreement and all other
                  agreements, instruments, documents, and certificates required
                  or reasonably requested by Purchaser or WCL in connection
                  therewith.

                  "WAI" shall mean Williams Aircraft, Inc., a Delaware
                  corporation, and the sole member of Williams Aircraft Leasing,
                  LLC, a Delaware limited liability company.

                  "WAL" shall mean Williams Aircraft Leasing, LLC, a Delaware
                  limited liability company.

                  "WCP" shall mean WilTel Communications Pty Limited (ACN 081
                  547 042), a corporation organized and existing under the laws
                  of Australia.

         3. Section 1.01 of the Agreement is hereby amended by deleting the
defined term "Cash Portion of the Purchase Price" therein in its entirety.

         4. Section 1.01 of the Agreement is hereby amended by amending and
restating the defined term "Financing Statements" in full to read as follows:

                  "Financing Statements" shall mean UCC-1 financing statements
                  for filing under the Uniform Commercial Code of each
                  jurisdiction as may be necessary or, in the reasonable opinion
                  of Seller, desirable to perfect the security interest created
                  by the Purchase Money Mortgage and the Pledge Agreement.



                                      -6-
<PAGE>
         5. Section 1.01 of the Agreement is hereby amended by amending and
restating the defined term "Purchase Money Mortgage" in full to read as follows:

                  "Purchase Money Mortgage" shall mean the Mortgage With Power
                  of Sale, Security Agreement, Assignment of Leases, Rents and
                  Profits, Financing Statement and Fixture Filing, to be granted
                  at Closing by Purchaser in favor of Seller in a form
                  reasonably acceptable to each of Purchaser and Seller.

         6. Section 1.01 of the Agreement is hereby amended by amending and
restating the defined term "WCG Bank Facility" in full to read as follows:

                  "WCG Bank Facility" shall mean the Second Amended and Restated
                  Credit and Guaranty Agreement dated as of September 8, 1999,
                  as amended and restated as of April 25, 2001, and as further
                  amended and restated as of October 15, 2002, among WCL, as
                  "Borrower", New WCG and the other Guarantors referred to
                  therein, the Lenders referred to therein, the Bank Agent, JP
                  Morgan Chase Bank as Syndication Agent, and Salomon Smith
                  Barney Inc. and Merrill Lynch & Co., as Co-Documentation
                  Agents (as further amended, restated, replaced, renewed,
                  extended, consolidated, modified, supplemented, refinanced or
                  refunded (in whole or in part), from time to time.

         7. Section 1.01 of the Agreement is hereby amended by amending the
defined term "Settlement Agreement" by adding thereto the phrase ", as amended,
restated, supplemented or otherwise modified from time to time" immediately
after the phrase "and the Transactions" set forth on the last line thereof.

         8. Section 1.01 of the Agreement is hereby amended by amending the
defined term "Master Lease" by adding thereto the phrase ", as amended,
restated, supplemented or otherwise modified from time to time" immediately
after the phrase "Real Property and Improvements" set forth on the last line
thereof.

         9. Section 2.02(a) and Section 2.02(b) of the Agreement are each hereby
amended and restated in full to read as follows:

                 "(a) Forty Four Million Eight Hundred Thousand Dollars
                      ($44,800,000) (which sum reflects the original $50,000,000
                      portion of the Purchase Price reduced by $5,200,000
                      relating to the net credits agreed to by the Parties
                      pursuant to the Construction Agreement), in the form of a
                      promissory note made by Purchaser and WCL, as co-issuers,
                      and guaranteed by New WCG (the "Short Term Note"). The
                      original principal amount of the Short-Term Note shall be
                      $44,800,000 (the "Loan"). The Short Term Note shall have
                      the stated face amount of $74,360,295.30 (the "Stated
                      Amount"), and reference to such amount shall include the
                      original principal amount of $44,800,000 and all accrued
                      but unpaid interest thereon. The calculation of the Stated
                      Amount shall assume that all interest payable under the
                      Short-Term Note shall accrue and be capitalized pursuant
                      to the terms set forth below and that the original



                                      -7-

<PAGE>

                      principal amount and all such accrued and capitalized
                      interest will be paid to Seller on December 29, 2006 (the
                      "Maturity Date"). All interest on the outstanding
                      principal balance of the Short Term Note shall accrue at
                      the following rates of interest during the following
                      periods and shall be capitalized to the outstanding
                      principal amount of the Loan at the end of such periods:
                      (i) first, at the initial rate of ten percent (10%) per
                      annum, commencing on the Closing Date and continuing
                      thereafter until December 31, 2003, and all such interest
                      that accrues and remains unpaid during such period shall
                      be capitalized as principal of the Short-Term Note on
                      December 31, 2003; (ii) second, at the rate of twelve
                      percent (12%) per annum, commencing on January 1, 2004 and
                      continuing thereafter until December 31, 2004, and all
                      such interest that accrues and remains unpaid during such
                      period shall be capitalized as principal of the Short-Term
                      Note on December 31, 2004; (iii) third, at the rate of
                      fourteen percent (14%) per annum, commencing on January 1,
                      2005 and continuing thereafter until December 31, 2005,
                      and all such interest that accrues and remains unpaid
                      during such period shall be capitalized as principal of
                      the Short-Term Note on December 31, 2005; and (iv) sixteen
                      percent (16%) per annum, commencing on January 1, 2006 and
                      continuing thereafter until the Maturity Date, and all
                      such interest that accrues and remains unpaid during such
                      period shall be payable on the Maturity Date.

                 (b)  One Hundred Million Dollars ($100,000,000) in the form of
                      a promissory note made by Purchaser and WCL, as
                      co-issuers, and guaranteed by New WCG (the "Long Term
                      Note") which amount may be reduced in accordance with
                      Section 2.08 and Section 7.21 hereof. The Long Term Note
                      shall bear interest at the rate of seven percent (7%) per
                      annum, amortized over 30 years, with the entire
                      outstanding principal balance and accrued but unpaid
                      interest thereon due and payable in full on the date which
                      is seven and one half (7 1/2) years from the Closing
                      Date."

         10. Section 2.03 of the Agreement is hereby amended by deleting the
phrase "simultaneously with the satisfaction or waiver of all of the conditions
set forth in Article V hereof, or at such other time and date as Seller and
Purchaser shall agree" set forth therein and substituting in lieu thereof the
phrase "on and as of October 15, 2002, provided that all conditions set forth in
Article V hereof are satisfied or waived".

         11. Section 2.04(f) of the Agreement is hereby amended by adding
thereto the phrase "and the Termination Statements" immediately after the phrase
"Initialed Title Commitment" set forth therein.

         12. Section 2.04(h) of the Agreement is hereby deleted in its entirety.

         13. Section 2.04(k) of the Agreement is hereby amended by deleting the
word "and" at the end of the second line thereof.



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<PAGE>

         14. Section 2.04(l) of the Agreement is hereby amended and restated in
full to read as follows:

                  "(l) the Side Letter, duly executed by Seller; and"

         15. Section 2.04 of the Agreement is hereby amended by adding thereto a
new subsection (m) to read as follows:

                  "(m) all other previously undelivered documents required by
                  this Agreement to be delivered by Seller to Purchaser at or
                  prior to the Closing in connection with the Transactions."

         16. Section 2.05(a) of the Agreement is hereby deleted in its entirety.

         17. Section 2.05(b) of the Agreement is hereby amended by adding
thereto the phrase "Pledge Agreement," immediately before the phrase "Purchase
Money Notes".

         18. Section 2.05(e) of the Agreement is hereby amended by (a) adding
thereto the phrase ", the Jones Day Legal Opinion and the New WCG Legal Opinion"
immediately after the phrase "Legal Opinion" and by deleting (b) the word "and"
set forth therein.

         19. Section 2.05(f) of the Agreement is hereby amended and restated in
full to read as follows:

                  "(f) the Side Letter, duly executed by Purchaser, WCL and New
                  WCG; and"

         20. Section 2.05 of the Agreement is hereby amended by adding thereto a
new subsection (g) to read as follows:

                  "(g) all other previously undelivered documents required by
                  this Agreement to be delivered by Purchaser to Seller at or
                  prior to the Closing in connection with the Transactions."

         21. Article II of the Agreement is hereby amended by adding thereto a
new Section 2.07 to read as follows:

                  "2.07 Delivery of Closing Documents. The parties hereto hereby
                  agree that all of the Building Purchase Closing Documents and
                  the Title Instruction Letter shall be executed (as applicable)
                  and, together with the Title Instruction Letter, shall be
                  delivered into escrow pursuant to the terms of the Escrow
                  Agreement; provided, however, that the Pledge Agreement,
                  Equitable Mortgage, the Australian Legal Opinion, the
                  Intercreditor Agreement (Pledge Agreement) and the related
                  UCC-1 shall be executed and delivered into Escrow on or before
                  October 23, 2002, in accordance with the terms and provisions
                  of the Escrow Agreement. The Escrow Agreement shall direct the
                  Escrow Agent to deliver certain of the Closing Documents and
                  the Title Instruction Letter to the Building Purchase Escrowee
                  to consummate the transactions contemplated by the Closing
                  Documents if the



                                      -9-
<PAGE>

                  conditions specified in the Escrow Agreement are met or waived
                  in accordance with the terms thereof."

         22. Article II of the Agreement is hereby amended by adding thereto a
new Section 2.08 to read as follows:

                  "2.08 True-Up.

                           (a) The parties hereto hereby agree that all
                  regularly scheduled payments due and owing by Purchaser to
                  Seller under the Master Lease and the Aircraft Dry Leases
                  during the Escrow Period shall be paid by Purchaser to Seller
                  in accordance with the terms of the Master Lease and the
                  Aircraft Dry Leases, respectively, during the Escrow Period
                  until the Escrow Period Termination Date. Upon the occurrence
                  of the Escrow Period Termination Date, Purchaser and Seller
                  shall calculate the difference and associated timing (if any)
                  of (a) the aggregate amount paid by Purchaser to Seller
                  pursuant to and in accordance with the Master Lease and the
                  Aircraft Dry Leases during the Escrow Period and (b) the
                  aggregate amount that would have been paid by the Co-Makers to
                  Seller under the Purchase Money Notes during the Escrow Period
                  (the "Escrow Period Differential") in the same manner set
                  forth on Schedule 2.08(a) attached hereto, and TWC, Seller,
                  WAI or any of their respective Affiliates receiving such
                  Escrow Period Differential shall thereafter immediately apply
                  or cause to be applied the Escrow Period Differential first to
                  accrued but unpaid interest of and then to outstanding
                  principal of the Long-Term Note as specifically set forth in
                  Schedule 2.08(a).

                           (b) If the Aircraft Dry Leases are refinanced at any
                  time during the Escrow Period (the "Aircraft Refinancing"),
                  (i) TWC and Seller shall on the date of any such Aircraft
                  Refinancing cause WAI to execute and deliver, and WCL shall
                  execute and deliver, the Williams Aircraft Leasing Purchase
                  Agreement and the other Williams Aircraft Leasing Transfer
                  Documents, (ii) Purchaser and Seller shall calculate in good
                  faith the net cash proceeds of such Aircraft Refinancing (the
                  "Aircraft Refinancing Net Cash Proceeds"), and (iii) TWC,
                  Seller, WAI or any of their respective Affiliates receiving
                  such Aircraft Refinancing Net Cash Proceeds shall immediately
                  thereafter apply or cause to be applied such Aircraft
                  Refinancing Net Cash Proceeds pro rata to the then outstanding
                  principal balances under the Master Lease specified on each of
                  the three amortization schedules attached hereto as Schedule
                  2.08(b)-1, Schedule 2.08(b)-2 and Schedule 2.08(b)-3,
                  respectively.

                           (c) If the Aircraft Refinancing occurs during the
                  Escrow Period and an Escrow Period Termination Date occurs
                  thereafter, TWC and Seller shall calculate in good faith the
                  Aircraft Refinancing Net Cash Proceeds and TWC, Seller, WAI or
                  any of their respective Affiliates receiving such Aircraft
                  Refinancing Net Cash Proceeds shall immediately thereafter
                  apply or cause to be



                                      -10-
<PAGE>

                  applied such Aircraft Refinancing Net Cash Proceeds first to
                  accrued but unpaid interest (if any) of and then to
                  outstanding principal of the Long-Term Note.

                           (d) If the Aircraft Refinancing does not occur during
                  the Escrow Period and an Escrow Period Breakage Date occurs,
                  the Master Lease, the Aircraft Dry Leases and the other
                  existing Sale Leaseback Transaction Documents shall continue
                  in full force and effect."

         23. Section 3.01 of the Agreement is hereby amended by (a) deleting the
word "and" set forth at the end of the last line of subsection (j) thereof; and
(b) deleting the period in the last line of subsection (k) thereof and
substituting in lieu thereof a semi-colon.

         24. Section 3.02 of the Agreement is hereby amended by (a) deleting the
word "and" set forth in the last line of subsection (f) thereof; and (b)
deleting the period in the last line of subsection (g) thereof and substituting
in lieu thereof a semi-colon.

         25. Article III of the Agreement is hereby amended by amending and
restating Section 3.05 set forth therein in full to read as follows:

                  "3.05 Survival and Continuation of Representations and
                  Warranties During Escrow Period. The parties hereto hereby
                  agree that all representations and warranties set forth in
                  this Article III shall survive the Closing Date and shall in
                  any event be true and correct on and as of the Escrow Period
                  Termination Date."

         26. Article IV of the Agreement is hereby amended by adding a new
Section 4.13 thereto to read as follows:

                  "4.13 Survival and Continuation of Covenants During Escrow
                  Period. The parties hereto hereby agree that the covenants
                  specified in Section 4.01, Section 4.02, Section 4.09, Section
                  4.10, Section 4.11 and Section 4.12 shall survive the Closing
                  Date and shall continue in full force and effect during the
                  Escrow Period until the occurrence of the Escrow Period
                  Termination Date."

         27. The caption immediately below the caption "ARTICLE V" of the
Agreement is hereby amended in full to read "CONDITIONS PRECEDENT; ESCROW PERIOD
DEFAULTS".

         28. Article V of the Agreement is hereby amended by adding thereto a
new Section 5.03 to read as follows:

                  "5.03 Escrow Period Purchase Agreement Defaults. The parties
                  hereto hereby agree that upon the occurrence and during the
                  continuance of an Escrow Period Purchase Agreement Default (a)
                  the defaulting party or parties shall upon obtaining notice of
                  such Escrow Period Purchase Agreement Default promptly
                  thereafter provide written notice of such Escrow Period
                  Default to each other non-defaulting party hereto, and
                  describe in reasonable detail therein the nature of such
                  Escrow Period Purchase Agreement Default and the actions
                  proposed to be



                                      -11-
<PAGE>

                  undertaken by such defaulting party or parties for the prompt
                  resolution and cure thereof; and (b) the non-defaulting party
                  or parties' remedy or remedies for any such Escrow Period
                  Purchase Agreement Default shall be limited solely to seeking
                  recovery of the actual damages incurred by such non-defaulting
                  party or parties arising in respect of such Escrow Period
                  Purchase Agreement Default (i) first, by seeking such recovery
                  under and pursuant to the Title Policies (if applicable) and
                  (ii) second, by seeking such recovery thereof from the
                  defaulting party or parties."

         29. Article V of the Agreement is hereby amended by adding thereto a
new Section 5.04 to read as follows:

                  "5.04 Escrow Period Sale Leaseback Defaults. The parties
                  hereto hereby agree that upon the occurrence and during the
                  continuance of a Sale Leaseback Default (a) the defaulting
                  party or parties shall upon the occurrence and during the
                  continuance of such Sale Leaseback Default promptly thereafter
                  provide written notice of such Sale Leaseback Default to each
                  other non-defaulting party hereto, and describe in reasonable
                  detail therein the nature of such Sale Leaseback Default and
                  the actions proposed to be undertaken by such defaulting party
                  or parties for the prompt resolution and cure thereof within
                  the applicable grace period provided under the Sale Leaseback
                  Transaction Documents, if any; and (b) the non-defaulting
                  party or parties shall, only for such Sale Leaseback Defaults
                  as are non-material and/or non-monetary, forbear from
                  exercising any rights or remedies available to it or them
                  under any Sale Leaseback Transaction Document until the
                  occurrence of the earlier of the Escrow Period Termination
                  Date or the Escrow Period Breakage Date, provided that there
                  shall be no termination or acceleration of the Master Lease
                  except for a payment default or cancellation of the insurance
                  required thereunder that in each case continues beyond one
                  Business Day after taking into account any applicable grace
                  period.

         30. Section 7.21 of the Agreement is hereby amended by deleting the
first, second, third and fourth sentences therefrom and substituting in lieu
thereof the following:

                  "The parties hereto hereby agree that (A) TWC, Seller, WAI and
                  WAL shall have the exclusive right to dispose of or refinance
                  the Aircraft Dry Leases on commercially reasonable terms and
                  at market rates prior to the Closing Date and (B) if TWC,
                  Seller, WAI and WAL shall not have disposed of or refinanced
                  the Aircraft Dry Leases by the Closing Date, then TWC, Seller,
                  WAI, WAL, WCL and WTC, shall each continue to be bound by the
                  terms and provisions of each Aircraft Dry Lease (as
                  applicable), provided that upon the occurrence of the Aircraft
                  Refinancing, TWC and Seller shall on the date of any such
                  Aircraft Refinancing cause WAI to execute and deliver, and WCL
                  shall execute and deliver, the Williams Aircraft Leasing
                  Purchase Agreement and the other Williams Aircraft Leasing
                  Transfer Documents, and TWC and Seller shall apply the
                  Aircraft Refinancing Net Cash Proceeds to accrued but unpaid
                  interest on and



                                      -12-
<PAGE>

                  outstanding principal of the Long-Term Note, all pursuant to
                  and in accordance with Section 2.08 hereof."

         31. Section 7.21 of the Agreement is further amended by (a) deleting
the term "Disposition" as set forth in the second sentence thereof (after giving
effect to the amendments to Section 7.21 of the Agreement as specified in
Section 28 of this Amendment) and substituting in lieu thereof the phrase
"Aircraft Refinancing or other disposition of the Aircraft"; and (b) deleting
therefrom the last sentence thereof.

         32. Article VII of the Agreement is hereby amended by adding a new
Section 7.26 thereto to read as follows:

                  "7.26. Side Letter. The parties hereto hereby agree to execute
                  and deliver the Side Letter on the Closing Date."

         33. The Agreement is hereby amended by adding thereto (a) a new
Schedule 2.08(a) in the form of Schedule 1 attached hereto; (b) a new Schedule
2.08(b)-1 in the form of Schedule 2 attached hereto; (c) a new Schedule
2.08(b)-2 in the form of Schedule 3 attached hereto; and (d) a new Schedule
2.08(b)-3 in the form of Schedule 4 attached hereto.

         34. Exhibit D (Permitted Exceptions) to the Agreement is hereby amended
and restated in its entirety in the form of Exhibit 1 attached hereto.

         35. The Agreement is hereby amended by adding thereto (a) a new Exhibit
E (Side Letter) in substantially the form of Exhibit 2 attached hereto; and (b)
a new Exhibit F (Williams Aircraft Leasing Transfer Agreement) in substantially
the form of Exhibit 3 attached hereto.

         36. The Agreement is hereby amended by (a) except as provided in
subsection (b) of this Paragraph 34, deleting the phrase "Purchase Money Note"
in each instance where it appears therein and substituting in lieu thereof in
each such instance the phrase "Purchase Money Notes" and (b) deleting the phrase
"Purchase Money Note" in each instance referenced in Section 7.21 of the
Agreement and substituting in lieu thereof in each such instance the phrase
"Long Term Note."

         37. The Agreement is hereby amended by deleting the phrase "Cash
Portion of the Purchase Price" in each instance where it appears therein.

         38. Purchaser, WCL, Communications and New WCG shall each use their
best efforts to ensure that any lien or security interest in the Acquired Assets
granted by any of them to the Bank Agent for the benefit of the Lenders under
Loan Documents shall be subject and fully subordinate to the first priority
mortgage liens and security interests granted by Purchaser to Seller in certain
of the Acquired Assets (except for the Excluded Property (as such term is
defined in the Purchase Money Mortgage)) pursuant to the Purchase Money Mortgage
(as the same may be amended, restated, supplemented or otherwise modified from
time to time) and the other rights and remedies of Seller pursuant thereto. Each
of New WCG, Purchaser, WCL, Communications and Seller hereby acknowledge and
agree that Purchaser may execute and deliver the Second Mortgage.



                                      -13-
<PAGE>

         39. The parties hereto agree to execute and deliver (or to cause the
execution and delivery of), on or prior to the Closing Date, each of (a) the POP
Easement Agreement dated as of October 15, 2002 between Seller and Williams
Field Services Company, a Delaware corporation, as "Grantors" and Purchaser, as
"Grantee", in the form of Exhibit 4 attached hereto; (b) the Satellite Easement
Agreement dated as of October 15, 2002 between Seller and Williams Field
Services Company, as "Grantors" and Purchaser, as "Grantee", in the form of
Exhibit 5 attached hereto; and (c) the First Amendment to Agreement for the
Resolution of Continuing Contract Disputes dated as of October 15, 2002, among
TWC, Communications and WCL, in the form of Exhibit 6 attached hereto.

         40. The parties hereto hereby agree that Exhibit 7 attached hereto
shall constitute, and shall be submitted by the parties hereto on or prior to
the Closing Date as, the Company Building Purchase Closing Documents and the TWC
Building Purchase Closing Documents set forth on Exhibit B to the Escrow
Agreement.

         41. Seller has requested that the other parties hereto agree to waive,
and the parties hereto hereby agree to waive, the requirement specified in
Section 2.04(i) of the Agreement that Seller deliver the consents specified in
Schedule 3.01(e) to the Agreement (each a "Consent" and collectively the
"Consents") at Closing (such waiver being hereinafter referred to as the
"Waiver"), provided that Seller shall promptly endeavor to obtain and deliver
each Consent to Purchaser. The Waiver shall be specifically limited as set forth
herein and shall not otherwise affect Seller's obligation to obtain and deliver
each Consent to Purchaser under this Agreement. As consideration for granting
the Waiver, Seller hereby agrees to indemnify, reimburse and hold harmless each
of Purchaser, WCL, New WCG and Communications and each of their respective
successors and assigns (hereinafter, an "Indemnitee" and collectively the
"Indemnitees"), to the fullest extent permitted by applicable law, from any and
all liabilities, obligations, damages, penalties, claims, demands, actions,
suits, judgments and any and all costs, expenses or disbursements (including
attorneys' fees and expenses reasonably incurred) (collectively, the
"Indemnified Liabilities") of whatsoever kind and nature imposed on or
reasonably incurred by any of the Indemnitees as a result of, relating to or
arising out of any actual or prospective claim, litigation or other proceeding
relating to or arising out of the Waiver or Seller's failure to obtain and
deliver any Consent to Purchaser, provided that no Indemnitee shall be
indemnified pursuant to this Section 41 for Indemnified Liabilities to the
extent caused by the gross negligence or willful misconduct of any Indemnitee
(as determined by a court of competent jurisdiction in a final non-appealable
decision) on or after the date hereof. The obligations of Seller under this
Section 41 shall survive and remain in full force and effect until Seller has
delivered each Consent specified on Schedule 3.01(e) to the Agreement to
Purchaser. Seller acknowledges and agrees that upon written notice by any
Indemnitee of the assertion of an Indemnified Liability, Seller shall assume
full responsibility for the defense thereof. Any amount due under this Section
41 shall be payable by Seller promptly upon and in any event within thirty (30)
days after receipt of written demand by any Indemnitee therefor. Each Indemnitee
agrees to use its best efforts to promptly notify Seller of any actual or
potential Indemnified Liability of which such Indemnitee has knowledge and to
specify in reasonable detail the nature and period of existence of any such
Indemnified Liability. Nothing contained in this Section 41 shall in any way
affect, modify, restrict or diminish any other rights or obligations of Seller,
Purchaser,



                                      -14-
<PAGE>

WCL, New WCG or Communications contained in the Agreement, the Purchase Money
Notes or the Purchase Money Mortgage.

         42. Each of WAI and New WCG (each a "New Transaction Party" and
collectively the "New Transaction Parties") by executing and delivering this
Amendment hereby expressly confirm that it has assumed, and agrees to perform
and observe, each and every one of the covenants, rights, promises, agreements,
terms, conditions, obligations, duties and liabilities applicable to it under
the Agreement (as amended by this Amendment) (each reference in this Section 42
to the "Agreement" shall mean the Agreement (as amended by this Amendment)).
Each New Transaction Party hereby represents and warrants that (a) such New
Transaction Party has the corporate power and authority to enter into the
Agreement by executing and delivering this Amendment; (b) the execution,
delivery and performance by such New Transaction Party of this Amendment and
such New Transaction Party's entering into the Agreement have been duly
authorized by its respective Board of Directors and no other corporate
proceedings on its part are necessary to authorize the execution, delivery and
performance of this Amendment and entering into the Agreement; and (c) this
Amendment has been duly executed and delivered by such New Transaction Party and
the Agreement constitutes such New Transaction Party's legal, valid and
enforceable obligation, enforceable against such New Transaction Party in
accordance with its terms, except as may be limited by applicable bankruptcy,
insolvency, reorganization or similar laws affecting creditors' rights generally
and by general principles of equity, whether such enforceability is considered
in a proceeding at law or in equity.

         43. This Amendment (and for each New Transaction Party, the Agreement
(as amended by the Amendment)) shall be binding upon each party hereto and shall
inure to the benefit of each party hereto and their respective successors and
permitted assigns.

         44. This Amendment may be executed in one or more counterparts, each of
which shall be deemed an original, but all of which shall constitute one and the
same instrument. The delivery of an executed counterpart to this Amendment by
facsimile shall be effective as delivery of a manually executed copy of this
Amendment.

         45. Except as specifically amended hereby, the Agreement is in all
respects confirmed, ratified and approved. All references in the Agreement to
"this Agreement" shall mean and refer to the Agreement as amended hereby.




                                      -15-
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Agreement on
and as of the date and year first above written.


                                    WILLIAMS HEADQUARTERS BUILDING COMPANY


                                    By: /s/ Jack D. McCarthy
                                        ----------------------------------------
                                        Title: Vice President


                                    WILLIAMS TECHNOLOGY CENTER, LLC

                                    By: WILLIAMS COMMUNICATIONS, LLC,
                                        its sole Member


                                    By: /s/ Howard S. Kalika
                                        ----------------------------------------
                                        Title: Vice President and Group
                                               Executive, Corporate Development
                                               and Finance and Assistant
                                               Secretary


                                    WILLIAMS COMMUNICATIONS, LLC


                                    By: /s/ Howard S. Kalika
                                        ----------------------------------------
                                        Title: Vice President and Group
                                               Executive, Corporate Development
                                               and Finance and Assistant
                                               Secretary


                                    WILLIAMS COMMUNICATIONS GROUP, INC.


                                    By: /s/ Howard S. Kalika
                                        ----------------------------------------
                                        Title: Vice President and Group
                                               Executive, Corporate Development
                                               and Finance and Assistant
                                               Secretary


                                    WILTEL COMMUNICATIONS GROUP, INC.


                                    By: /s/ Howard S. Kalika
                                        ----------------------------------------
                                        Title: Vice President and Group
                                               Executive, Corporate Development
                                               and Finance and Assistant
                                               Secretary




                                      -16-
<PAGE>

                                    WILLIAMS AIRCRAFT LEASING, LLC

                                    By: WILLIAMS AIRCRAFT, INC., its sole member

                                        By: /s/ Jack D. McCarthy
                                            ------------------------------------
                                            Title: Vice President


                                    WILLIAMS AIRCRAFT, INC.


                                    By: /s/ Jack D. McCarthy
                                        ----------------------------------------
                                        Title: Vice President



                                      -17-