<PAGE>




                                INTERIM AGREEMENT

         This Interim Agreement is entered into by and among Winstar Wireless,
Inc., Winstar Communications, Inc. and Williams Communications, LLC (f/k/a
Williams Communications, Inc.) as of the Effective Date (as defined below).

         Subject to the approval of the United States Bankruptcy Court for the
District of Delaware (the Bankruptcy Court"), Winstar Wireless, Inc.
("Wireless") and Winstar Communications, Inc. (together with Wireless,
"Winstar") and Williams Communications, LLC (f/k/a Williams Communications,
Inc.) ("Williams") hereby agree as follows:

1.       Definitions:

(a)      "Long-Haul Agreement" shall mean the contract entitled "IRU Agreement
         Between Winstar Wireless, Inc. and Williams Communications, Inc. dated
         December 17, 1998 (Long-Haul)";

(b)      "Clarification Agreement" shall mean the contract entitled
         "Clarification Agreement to IRU Agreement (Long-Haul) Between Winstar
         Wireless, Inc. and Williams Communications, Inc." dated as of December
         17, 1998;

(c)      "Modification Agreement" shall mean the contract entitled "Amendment
         to IRU Agreement (Long-Haul) Between Winstar Wireless, Inc. and
         Williams Communications, Inc." dated April 1, 1999;

(d)      "IRU Agreements" shall mean the Long-Haul Agreement, the Clarification
         Agreement, the Modification Agreement, and any and all amendments to
         any and all of them;

(e)      "New IRU Agreement" shall have the meaning specified in Section 5;

(f)      "Wireless IRU" shall mean the contract entitled "Wireless Fiber IRU
         Agreement By and Between Winstar Wireless, Inc. and Williams
         Communications, Inc." effective as of December 17, 1998;

(g)      "DIP Credit Agreement" shall mean the Second Amended and Restated
         Senior Secured Super-Priority Debtor In Possession Credit Agreement
         dated as of July 9, 2001 among WCI Capital Corporation, a Delaware
         corporation and debtor and debtor-in-possession as the Borrower,
         Winstar Communications, Inc., a Delaware corporation and debtor and
         debtor-in-possession, the Subsidiary Guarantors from time to time
         parties thereto, each of the lenders (collectively, the "Lenders") and
         the letter of credit issuer (the "L/C Issuer") from time to time
         parties thereto, and Citicorp USA, Inc., as administrative agent for
         the Lenders and the L/C Issuer, The Bank of New York, as collateral
         agent for the Lenders and the L/C Issuer, and Salomon Smith Barney
         Inc., BNY Capital Markets, Inc., CIBC World Markets Corp., Credit
         Suisse First Boston and J.P. Morgan, a division of Chase Securities
         Inc., as co-syndication agents and co-documentation agents for the
         Lenders and the L/C Issuer;

(h)      "Effective Date" shall mean June 30, 2001;

(i)      "Closing Date" shall mean the date no later than the second business
         day following the date of the entry of an Order of the Bankruptcy Court
         approving this Interim Agreement, or such other date as the parties
         hereto may mutually agree upon in writing;

(j)      "Interim Period" shall mean the period on and from the Effective Date
         until the earliest to occur of (i) the New IRU Commencement Date, (ii)
         the date of termination of this Interim Agreement or of this Interim
         Period; (iii) the date on which Winstar's bankruptcy case is dismissed
         or converted to a Chapter 7 case; or (iv) if Wireless has not delivered
         to Williams a Notice of Election (as that term




<PAGE>






         is defined in the Option Agreement) in respect of Option 2 (as that
         term is defined in the Option Agreement) one (1) day after the Deadline
         for Exercise (as that term is defined in the Option Agreement);

(k)      "New IRU Commencement Date" shall have the meaning specified in the
         Option Agreement;

(l)      "Standstill Agreement" shall mean the Standstill Agreement between
         Winstar Wireless, Inc., Winstar Communications, Inc. and Williams
         Communications, LLC dated May 8, 2001, as amended by the Amendment of
         Standstill Agreement dated June 6, 2001;

(m)      "Option Agreement" shall have the meaning specified in Section 5.

2.       (a) This Interim Agreement shall be effective as of the Effective Date,
provided, however, that if (a) the Bankruptcy Court enters an Order disallowing
this Interim Agreement, or (b) on or before September 19, 2001 or such other
date as the parties hereto may mutually agree upon in writing, (i) this Interim
Agreement is not approved by Order of the Bankruptcy Court substantially in the
form of Exhibit A hereto, and (ii) the Collateral Agent and the Administrative
Agent (under, and as defined in the DIP Credit Agreement) shall not have
provided their written consent to the provisions of Section 7(c) of this Interim
Agreement in the form of Exhibit B hereto, this Interim Agreement shall be null
and void ab initio. Simultaneously with the execution of this Interim Agreement,
Winstar and Williams shall (x) duly execute an Amendment No. 2 of Standstill
Agreement in the form of Exhibit C hereto, and (y) Winstar shall pay
$1,384,615.00 to Williams by wire transfer of immediately available funds to the
United States account designated by Williams in payment of amounts owed to
Williams under the Standstill Agreement.

         (b) Williams agrees that it will not request, directly or indirectly,
that Winstar's bankruptcy case be converted to a Chapter 7 case.

3.       As and from the Closing Date, Winstar agrees that the IRU Agreements
shall be deemed to have been terminated prior to the date on which Winstar filed
its petition under Chapter 11 of the United States Bankruptcy Code in the
Bankruptcy Court.

4.       On the Closing Date, Williams and Winstar shall each duly execute and
deliver to the other a Mutual Release in the form of Exhibit D hereto, to be
effective as of the Effective Date.

5.       On the Closing Date, Williams and Wireless shall each duly execute and
deliver to the other an Option Agreement (the "Option Agreement") in the form of
Exhibit E hereto, and Williams shall duly execute and deliver to Wireless an IRU
agreement (the "New IRU Agreement") in the form of Exhibit 1 to the Option
Agreement.

6.       (a) On the Closing Date, Williams and Wireless shall each duly execute
and deliver to the other an agreement amending the Wireless IRU in the form of
Exhibit F hereto.

         (b) Winstar agrees that assumption of the Wireless IRU is a condition
precedent to the exercise of the option to enter the New IRU Agreement, as
provided in the Option Agreement, provided that nothing in this Interim
Agreement shall require Winstar to assume the Wireless IRU. In the event that
Winstar rejects the Wireless IRU (i) Williams may terminate this Interim
Agreement (A) on one-hundred twenty (120) days' prior written notice following
the effective date of such rejection or, (B) if Winstar provides written notice
to Williams within 10 days of the rejection of the Wireless IRU that it wishes
to extend the interval between rejection of the Wireless IRU and termination of
this Interim Agreement (the "One Year Notice"), for up to twelve (12) months'
from the date of the rejection of the Wireless IRU, this Interim Agreement shall
remain in effect for the time period requested in Winstar's One-Year Notice not
to exceed twelve (12) months from the rejection of the Wireless IRU, provided
that in the event Winstar provides the One Year Notice pursuant to this
subparagraph (B), Winstar shall be obligated to make payments to Williams in
accordance with the Interim Agreement without deferral, and (ii) Williams shall
have an equivalent number of days following the effective date of such rejection
to transfer its customers off the Wireless IRU as Winstar's interval between
rejection of the Wireless IRU and termination of this


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<PAGE>









Interim Agreement.. (c) Winstar and Williams each agree that the execution and
delivery of the Option Agreement is consideration for the other party to execute
the amendment to the Wireless IRU, and the execution of the amendment to the
Wireless IRU is consideration for the other party to execute the Option
Agreement. Winstar and Williams further agree that, if the option under the
Option Agreement is exercised, the Wireless IRU, as amended, and the New IRU
Agreement are intended to be, and shall be treated for all purposes as, a single
integrated agreement. Accordingly, in the event that Williams becomes the
subject of a case under the United States Bankruptcy Code, Williams agrees that
the Wireless IRU, as amended, and the New IRU Agreement shall be treated as a
single integrated agreement for purposes of 11 U.S.C. 365.

7.       During the Interim Period, Williams will provide services, capacity and
fiber to Winstar equivalent to those proposed to be provided under the New IRU
Agreement on the terms and conditions set forth in the New IRU Agreement, except
as specifically provided below in this Section 7:

         (a)      Winstar's purchase price for (i) international voice minutes
                  for which Sprint is Williams's underlying carrier, (ii)
                  Ancillary Services (as that term is defined in the New IRU
                  Agreement, and (iii) domestic voice minutes for which Sprint
                  is Williams's underlying carrier shall be the same price that
                  Williams pays Sprint for those minutes or Ancillary Services
                  (the "Pass-Through Price"). Winstar shall have one hundred
                  twenty (120) days from the Effective Date of this Agreement to
                  move this traffic to Sprint or any other carrier chosen by
                  Winstar. Winstar shall be liable for any termination charges,
                  if any, that Williams is required to pay to Sprint as a result
                  of Winstar moving this traffic directly to Sprint. Williams
                  will reasonably cooperate (without additional charge from
                  Williams) in effectuating such movement, and at Winstar's
                  request shall assign this traffic back to Winstar. In
                  addition, Winstar will pay Williams for the Off-Net data
                  circuits (from various identified vendors) set forth on
                  Exhibit G hereto at the rates set forth on that Exhibit.
                  Williams shall issue an invoice monthly for all amounts owing
                  under this Section 7(a).

         (b)      All amounts stated on each monthly invoice issued pursuant to
                  Section 7(a) of this Interim Agreement are due and payable
                  thirty (30) days after Winstar's receipt of the invoice by
                  wire transfer of immediately available funds to the United
                  States account designated by Williams, provided, however, that
                  amounts owing for the month of July 2001 shall be due and
                  payable two (2) business days after the later to occur of (i)
                  Winstar having received funding pursuant to the DIP Credit
                  Agreement, and (ii) the date of entry of an Order of the
                  Bankruptcy Court approving this Interim Agreement, and
                  provided, further that Winstar may withhold payment of any
                  particular charges that Winstar disputes in good faith and for
                  which it promptly gives written notice to Williams, stating
                  the details of such dispute. Upon reasonable prior written
                  notice, Williams will cooperate with Winstar in obtaining,
                  auditing and challenging, as appropriate, in a timely manner,
                  all statements for services provided by third-party vendors to
                  Williams for which payments are required under Section 7(a) of
                  this Interim Agreement.

         (c)      Commencing after the Effective Date, Winstar will pay Williams
                  $2,669,508.00 per month for all other services, capacity and
                  fiber provided under this Interim Agreement (including On-Net
                  services (as that term is defined in the New IRU Agreement)),
                  provided, however, that this monthly payment does not include
                  any charges for any circuits other than those circuits
                  identified in Exhibit H hereto, and provided, further,
                  however, that, until the Commitment Termination Date under the
                  DIP Credit Agreement (which date shall not be extended with
                  respect to Williams without the prior written consent of
                  Williams), all such amounts owed (including this monthly
                  payment) will be accrued and payment deferred until the
                  Commitment Termination Date under the DIP Credit Agreement
                  (the "Deferred Payments"), and provided, further, that the
                  Deferred Payments shall be reduced prospectively to the extent
                  that services, capacity and/or fiber provided by Williams are
                  reduced at Winstar's request. The Deferred Payments will, as
                  adequate protection pursuant to Bankruptcy Code section
                  363(e), be secured by the collateral under the DIP Credit
                  Agreement (as defined therein, the "Collateral"). Williams
                  will be entitled to liens in the Collateral that are pari
                  passu with the liens granted in favor of the Collateral Agent
                  (as defined in the DIP Credit Agreement), Williams shall be
                  deemed to have the status of a Secured Party (under, and as
                  defined in, the DIP Credit Agreement), and the obligations
                  owing to Winstar in respect of



                                       3
<PAGE>






                  the Deferred Payments shall be deemed to be Secured
                  Obligations (under, and as defined in, the DIP Credit
                  Agreement). As a consequence thereof, Williams is entitled to
                  the benefit of the Collateral Agent's liens on the Collateral
                  to secure the obligations owing to Williams in respect of the
                  Deferred Payments (including interest thereon, which will
                  accrue at the same rate at which interest accrues under the
                  DIP Credit Agreement) on the same basis as the Lenders (or any
                  other parties granted liens on a pari passu basis with the
                  Lenders) are entitled to the benefit of such liens to secure
                  their Secured Obligations. Williams shall not be entitled to
                  the benefit of the Collateral Agent's liens on the Collateral
                  for obligations other than the Deferred Payments as described
                  in this Section 7(c). Williams hereby irrevocably appoints the
                  Collateral Agent under the DIP Credit Agreement as its
                  collateral agent on terms and conditions similar to the terms
                  and conditions under which the Collateral Agent was appointed
                  by the other Secured Parties pursuant to and in accordance
                  with the DIP Credit Agreement, provided, however, that
                  Williams shall not take any action, initiate any suit or
                  proceeding, join with any creditor or party in interest in
                  commencing, directly or indirectly, any proceeding to enforce
                  any rights in respect of the Collateral, or demand or seek to
                  compel the Collateral Agent take any action whatsoever in
                  respect of the Collateral, except that Williams shall be
                  entitled to receive its pro rata share of any payments
                  (including, without limitation, any prepayments) made to the
                  DIP Lenders in respect of principal or interest under the DIP
                  Credit Agreement (including, without limitation, through the
                  realization of the Collateral) and Williams shall, subject to
                  the terms and conditions hereof, be able to take appropriate
                  action to enforce or terminate its contractual rights against
                  Winstar without it being deemed to be an action with respect
                  to Collateral. Notwithstanding that Williams shall be deemed
                  to have the status of a Secured Party for the limited purposes
                  described herein, Williams shall not be deemed to be a
                  "Lender" under the DIP Credit Agreement, and shall not have
                  any rights of a Lender, other than those expressly set forth
                  herein. All Deferred Payments shall be payable to Williams by
                  wire transfer on the Commitment Termination Date under the DIP
                  Credit Agreement.

         (d)      Williams shall not be obligated to provide to Winstar during
                  the Interim Period any additional services unless negotiated
                  in advance and additional payment arrangements are agreed to
                  in a writing executed by the parties.

8.       The parties will work together to migrate off of Williams's network all
long-distance services currently used by Winstar, including WorldCom, AT&T, and
Williams. Williams will assist Winstar at no expense to Winstar with these
migrations, provided, however, that any termination charges that Williams is
required to pay to WorldCom or AT&T in connection with these migrations shall be
paid by Winstar and are due and payable thirty (30) days after Winstar's receipt
of the invoice by wire transfer of immediately available funds to the United
States account designated by Williams.

9.       The parties will work together to transfer the WorldCom Off-Net data
circuits back to WorldCom and the payments set forth in Section 7(a) of this
Interim Agreement shall be reduced by the costs that the parties allocate to
WorldCom's circuits. If Winstar migrates off or otherwise terminates any other
Off-Net data circuit set forth on Exhibit G, the rates set forth on Exhibit G
shall be reduced by the costs that the parties allocate to such circuits,
effective upon the date that Winstar migrates off or otherwise terminates such
Off-Net data circuit. Winstar agrees that if Williams is required to pay any
termination charges in connection with such transfers, then these termination
charges shall be paid by Winstar and are due and payable thirty (30) days after
Winstar's receipt of the invoice by wire transfer of immediately available funds
to the United States account designated by Williams.

10.      Immediately upon the entry of an Order of the Bankruptcy Court
approving this Interim Agreement, Winstar's right to collocate its facilities in
Williams' facilities in the cities listed below shall terminate. Williams will
not charge Winstar any termination liability, and Winstar shall not be
responsible for any costs in connection with these facilities as of the
Effective Date. Winstar represents and warrants that it does not have equipment
collocated in Williams facilities in the cities listed below.

Albany
Austin
Boston


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Buffalo
Chattanooga
Columbia, MO
El Paso
Hartford
Herndon
Louisville
Madison
Nashville
Oakland
Pittsburgh
Rochester
San Antonio
San Francisco
Springfield, IL
Springfield, MA
Syracuse
Tucson
Tulsa Warehouse
Worcester, MA

Winstar may terminate its right to collocate its facilities in Williams
facilities in other cities on five (5) business days' written notice to
Williams. Williams will not charge Winstar any termination liability in
connection with such terminations, and Winstar shall not be responsible for any
costs in connection with such facilities as of the date of such termination(s).
Winstar will remove any equipment from such sites and entirely vacate such sites
within sixty (60) days of the date of such termination(s).

11.      If Winstar fails to make any payment due and payable under this Interim
Agreement or materially defaults under this Interim Agreement, Williams may, on
five (5) business days' written notice, terminate this Interim Agreement and
stop providing services to Winstar under this Interim Agreement, provided,
however, that Williams may not terminate this Interim Agreement or stop
providing any services if Winstar cures such payment default or takes good faith
action to cure such material non-payment default during such five (5) business
day cure period.

12.      The parties hereto agree that irreparable damage would occur in the
event Sections 4, 5 or 6(a), (b) or (c) of this Interim Agreement were not
performed in accordance with the terms hereof and that the parties shall be
entitled to specific performance of the terms hereof, in addition to any other
remedy at law or in equity.

13.      This Interim Agreement, and all matters arising out of or relating to
this Agreement and all transactions and events contemplated thereby, shall be
governed by, and construed, performed, and enforced in accordance with, the laws
of the State of New York, without giving effect to its conflict of law rules.

14.      No provision of this Interim Agreement can be changed, waived,
discharged, or terminated except by an instrument in writing signed by the party
to be charged and expressly referring to the provision of this Interim Agreement
to which such instrument relates; and no such waiver shall extend to, affect or
impair any right with respect to any obligation which is not expressly dealt
with therein. No course of dealing or delay or omissions on the part of the
parties in exercising any right shall operate as a waiver thereof or otherwise
be prejudicial thereto.

15.      If any term or other provision of this Interim Agreement is invalid,
illegal or incapable of being enforced by any law or public policy, subject to
Section 2 of this Interim Agreement, all other terms and provisions of this
Interim Agreement shall nevertheless remain in full force and effect for so long
as the economic or legal substance of the transactions contemplated by this
Interim Agreement is not affected in any manner materially adverse to any party.
Upon such determination that any term or other provision is




                                       5
<PAGE>



invalid, illegal or incapable of being enforced, the parties hereto shall
negotiate in good faith to modify this Interim Agreement so as to effect the
original intent of the parties as closely as possible in an acceptable manner in
order that the actions contemplated by this Interim Agreement are consummated
as originally contemplated to the greatest extent possible.

16.      All notices and other communications under this Interim Agreement shall
be in writing and shall be sent in accordance with Section 19 of the New IRU
Agreement, which shall apply to this Interim Agreement.

17.      Winstar agrees to file a motion with the Bankruptcy Court to seek
approval of this Interim Agreement no later than August 10, 2001, including
seeking approval of Winstar's execution and delivery of the Mutual Release and
Wireless's execution and delivery of the Option Agreement and option to enter
into the New IRU Agreement on the terms and conditions set forth therein.

18.      Winstar shall have the right to terminate the Interim Period or this
Interim Agreement on thirty (30) days written notice to Williams, provided,
however, that termination of the Interim Period or this Interim Agreement
pursuant to this Section 18 or Sections 11 or 6(b) of this Interim Agreement or
expiration of the Interim Period will not affect Williams' rights to collect all
money that is due and owing to Williams by Winstar prior to such termination and
will not affect Williams' rights under Section 7(c) of this Interim Agreement.
It shall be Winstar's obligation to satisfy any regulatory notice requirements
to its end users that arise from any such termination.

19.      This Interim Agreement constitutes the entire agreement between the
parties with respect to the subject matter of this Interim Agreement, and
supersedes all prior agreements, whether written or oral, with respect to that
subject matter.




Winstar Wireless, Inc.


By:  /s/ C.Z. CZERNER
   --------------------------------

Title:  Senior VP-Corporate Dev
      -----------------------------

Date:   Aug. 15, 2001
     ------------------------------

Williams Communications, LLC

By:  /s/ C.Z. CZERNER
   --------------------------------

Title:  Senior VP-Corporate Dev
      -----------------------------

Date:   Aug. 15, 2001
     ------------------------------


Williams Communications, LLC.

By:  /s/ FRANK SEMPLE
   --------------------------------

Title:
      -----------------------------

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




                                       6

<PAGE>




                                 August 15, 2001




Williams Communication, LLC
One Williams Center
Suite 4100
Tulsa, Oklahoma 74172-0172
Attention:   Bryan J. Dancer


                     Amendment No. 2 of Standstill Agreement

Dear Sirs:

         This will confirm that Winstar Wireless, Inc. and Winstar
Communications, Inc. (collectively, "Winstar") and Williams Communications, LLC
(f/k/a Williams Communications, Inc.) ("Williams") hereby agree as follows:

1. The Standstill Agreement, dated as of May 8, 2001, between Winstar and
Williams, as amended by letter agreement dated June 6, 2001 (the "Standstill
Agreement"), shall be deemed to have been terminated at 11:59 p.m. on June 29,
2001; provided, however, that if either (a) the United States Bankruptcy Court
for the District of Delaware (the "Bankruptcy Court") enters an Order
disallowing the Interim Agreement between Winstar and Williams (the "Interim
Agreement"), or (b) on or before September 19, 2001 or such other date as the
parties hereto may mutually agree upon in writing. (i) the Interim Agreement is
not approved by Order of the Bankruptcy Court substantially in the form of
Exhibit A to the Interim Agreement, and (ii) the Collateral Agent and the
Administrative Agent (under, and as defined in the DIP Credit Agreement) shall
not have provided their written consent to the provisions of Section 7(c) of the
Interim Agreement in the form of Exhibit B to the Interim Agreement (the earlier
of the date on which either of the events specified in sub-paragraphs (a) and
(b) occurs being the "Drop Dead Date"), the parties agree that the Standstill
Agreement shall not be deemed to have been so terminated and, notwithstanding
Section 1(f) of the Standstill Agreement, the Standstill Agreement shall be
deemed to have continued to remain in full force and effect through 11:59 p.m.
on June 29, 2001 to the Drop Dead Date, and therefrom shall continue to remain
in full force and effect.

2. This Agreement, and all matters arising out of or relating to this Agreement
and all transactions and events contemplated thereby, shall be governed by, and
construed, performed and enforced in accordance with, the laws of the State of
New York, without giving effect to its conflict of law rules.



Very truly yours,




WINSTAR COMMUNICATIONS, INC. AND WINSTAR WIRELESS, INC.

By: /s/ C. Z. CZERNER
   ----------------------------------
     C.Z. Czerner
     Senior Vice President -- Corporate Development




<PAGE>



AGREED AND ACCEPTED
this 15 day of August, 2001:



WILLIAMS COMMUNICATIONS, LLC


By: /s/ BRYAN J. DANCER
   ----------------------------------
     Bryan J. Dancer
     Vice President Business Development



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