EXHIBIT 10.7
                                                                    ------------



                              CINGULAR WIRELESS LLC
                                SBC WIRELESS LLC
                            5565 GLENRIDGE CONNECTOR
                                   SUITE 2000
                             ATLANTA, GEORGIA 30342

                                                                    May 15, 2002

Southern Towers, Inc.
SpectraSite Holdings, Inc.
and SpectraSite Communications, Inc.
c/o SpectraSite Communications, Inc.
100 Regency Forest Drive, Suite 400
Cary, North Carolina 27511

SBC Tower Holdings LLC
c/o SBC Communications Inc.
175 E. Houston
San Antonio, Texas 78205

                       Re: Transaction Documents Amendment


Ladies and Gentlemen:

         Reference is made to those certain agreements and amendments thereto
identified and defined on SCHEDULE A hereto (the "Transaction Documents").
Capitalized terms used and not defined herein shall have the respective meanings
ascribed thereto in the Agreement to Sublease (as amended and modified from time
to time).

         This letter agreement will confirm the understanding and agreement
between the parties hereto as follows:

         1. TRANSACTION DOCUMENTS. Subject to the provisions of this letter
agreement and notwithstanding anything to the contrary contained in the
Transaction Documents, the parties agree to and acknowledge the following
modifications to the Transaction Documents. Except as expressly amended hereby
or by other documents executed on or about the date hereof and described on
SCHEDULE C, the Transaction Documents shall remain in full force and effect.

             (a) The parties hereto agree that in accordance with Section 16.19
      of the Agreement to Sublease and for good and valuable consideration
      including all provisions set forth herein, on the Effective Date (as
      defined herein) the Agreement to Sublease is hereby amended and modified
      as follows:


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                 (i)  The definition of "Site" is hereby amended to delete from
             said definition and from Annex A to the Agreement to Sublease 187
             sites located in California and Nevada identified on the attached
             SCHEDULE B (the "California and Nevada Unclosed Sites").
             Without limiting the foregoing, the California and Nevada Unclosed
             Sites shall not be deemed to constitute Existing Sites, Excluded
             Sites or Included Sites thereunder or under any Transaction
             Document, and in no event shall more than 3,413 Sites become
             Included Sites under the Agreement to Sublease.

                  (ii) Article XV of the Agreement to Sublease is hereby deleted
             therefrom and shall have no further force or effect.

                  (iii) On the Effective Date, TowerCo Parent shall issue
             12,144,381 shares of Parent Stock (which number of shares is
             subject to appropriate adjustment in the event of any stock
             dividends, splits, reverse splits, combinations or subdivisions
             occurring prior to the Effective Date) to SBC Tower Holdings LLC
             ("SBC TowerCo") in full satisfaction of its obligation to pay (x)
             the Stock Portion of the prepaid Rent pursuant to Sections 3.2(a)
             and (b) of the Agreement to Sublease for any and all of the
             remaining 707 Transfer Sites and (y) any adjustments with respect
             to the Parent Stock required under Sections 3.2(c)-(i) of the
             Agreement to Sublease. The parties agree and acknowledge that with
             respect to each Transfer Closing, Tower Co and TowerCo Parent shall
             only be obligated to pay the Cash Portion of the prepaid Rent with
             respect to each Transfer Site that becomes an Included Site at a
             Transfer Closing and that TowerCo and TowerCo Parent shall have no
             further obligations to issue any Parent Stock in connection with
             the transactions contemplated by the Agreement to Sublease.

             (b) From and after the Effective Date, all obligations and rights
      of the parties to the Site Marketing Agreement shall be terminated with
      respect to the California and Nevada Sites (as defined below), including,
      without limitation, the obligation and right of Marketer (as defined in
      the Site Marketing Agreement) to provide marketing services for the
      California and Nevada Sites and the right of the Marketer to receive fees


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      and other compensation thereunder with respect to the California and
      Nevada Sites (whether or not Marketer has provided marketing services with
      respect thereto prior to the effective date of this letter agreement);
      PROVIDED, HOWEVER, that the foregoing shall not constitute a release of,
      and the parties to the Site Marketing Agreement shall each retain, any
      other liability or obligation of such party to the extent arising out of
      events occurring or actions taken prior to the effective date of this
      letter agreement (including, without limitation, the parties' rights to
      indemnification as provided in Section 19 of the Site Marketing
      Agreement). For purposes hereof, the "California and Nevada Sites" are
      collectively all Sites located in California or Nevada.

             (c) The Lease and Sublease shall be amended to the extent and as
      provided in that certain Consent and Modification Agreement dated as of
      May __, 2002.

         2. SPECIAL PAYMENT.

         For and in consideration of the amendment to the Transaction Documents
outlined above, the various other agreements and undertakings of the parties
contained herein and the various agreements and undertakings of the parties
contained in the Joint Side Letter (as such term is defined in the Purchase
Agreement), on the Effective Date, TowerCo shall be obligated to pay to SBC
TowerCo Ten Million Dollars ($10,000,000) (the "Special Payment"). The parties
acknowledge and agree (i) that said obligation will be assigned to and assumed
by CA/NV Tower Holdings, LLC ("Newco") pursuant to the Assignment and Assumption
Agreement (as such term is defined in the Purchase Agreement) and (ii) that such
assignment and assumption is hereby consented to and shall in no manner affect
the Joint Side Letter by, between and among the parties hereto executed
contemporaneously herewith. The parties agree and acknowledge that upon the
consummation of the transactions contemplated by the Purchase Agreement, none of
the SCI Releasees (as such term is defined in the Joint Side Letter) shall have
any obligation or liability with respect to the fulfillment of Newco's
obligation to pay the Special Payment, and that immediately after the closing of
the transactions contemplated by the Purchase Agreement, Newco shall pay the
Special Payment to SBC TowerCo.

         3. BINDING EFFECT. This letter agreement shall be binding upon and
shall inure to the benefit of the parties hereto and their
respective legal representatives, successors and assigns and may not be modified
or amended except by a written agreement executed by all parties hereto.

         4. COUNTERPARTS. This letter agreement may be executed in several
counterparts, each of which shall be deemed an original, and all of such
counterparts together shall constitute one and the same instrument.

         5. GOVERNING LAW. The parties agree that this letter agreement shall be
governed by and construed in all respects in accordance with the laws of the
State of New York, without regard to its conflicts of law or choice of law
principles.


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         6. SEVERABILITY. Any term or provision of this letter agreement which
is invalid or unenforceable in any jurisdiction shall, as to that jurisdiction,
be ineffective to the extent of such invalidity or unenforceability without
rendering invalid or unenforceable the remaining terms and provisions of this
letter agreement in any other jurisdiction. If any provision of this letter
agreement is so broad as to be unenforceable, the provision shall be interpreted
to be only so broad as is enforceable.

         7. EFFECTIVENESS. Except as set forth in the next sentence, this
Agreement shall become effective upon the Closing (as defined in the Purchase
Agreement) of the transactions contemplated by the Purchase Agreement (the
"Effective Date"); provided that if the Purchase Agreement is terminated in
accordance with its terms prior to the Closing thereunder, this letter agreement
shall terminate and be null and void. Notwithstanding the preceding sentence,
Sections 1(a)(i) and 2 of this letter agreement shall not become effective on
the Effective Date if all of the consents with respect to the acquisition of the
California and Nevada Unclosed Sites by Cingular Wireless LLC from SBC TowerCo,
if any (the "Consents"), required by the GSM Facilities, LLC Limited Liability
Company Agreement shall have not been obtained in the manner and to the extent
required by such agreement prior to the Effective Date. For purposes of clarity,
if the Consents are not obtained prior the Effective Date, Sections 1(a)(i) and
2 of this letter agreement shall be null and void.

         8. RECEIPT OF THIRD PARTY CONSENTS. Cingular Wireless LLC shall use
commercially reasonably efforts to cause the receipt of the consents referred to
in Section 7 as promptly as practicable following the date hereof.

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         Please confirm your acceptance of and agreement to the foregoing by
signing and returning the accompanying copy of this letter agreement, whereupon
this letter agreement shall become binding on the parties hereto.

                                    CINGULAR WIRELESS LLC


                                    By: /s/ Stephen A. McGaw
                                       ---------------------------------
                                       Name:  Stephen A. McGaw
                                       Title: Executive Vice President-
                                              Corporate Development

                                    SBC WIRELESS LLC


                                    By: /s/ Stephen A. McGaw
                                       ---------------------------------
                                       Name:  Stephen A. McGaw
                                       Title: Executive Vice President-
                                              Corporate Development

The undersigned accept and agree to the
Foregoing, as of the date first written
above:

SBC TOWER HOLDINGS, LLC


By: /s/ James S. Kahan
   ------------------------------------
   Name:  James S. Kahan
   Title: President


SPECTRASITE HOLDINGS, INC.


By: /s/ Stephen H. Clark
   ------------------------------------
   Name:  Stephen H. Clark
   Title: President and CEO


SOUTHERN TOWERS, INC.


By: /s/ Stephen H. Clark
   ------------------------------------
   Name:  Stephen H. Clark
   Title: President and CEO


SPECTRASITE COMMUNICATIONS, INC.


By: /s/ Stephen H. Clark
   ------------------------------------
   Name:  Stephen H. Clark
   Title: President and CEO