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                                                                    EXHIBIT 10.6

                                        October 3, 2002

SpectraSite Holdings, Inc.
100 Regency Forest
Suite 400
Cary, NC 27511

Gentlemen:

         Each of the parties set forth on Annex A hereto (collectively with
their successors, the "WCAS SHAREHOLDERS") hereby irrevocably agrees with
SpectraSite Holdings, Inc. (the "COMPANY") with respect to any vote submitted to
the common stockholders of the Company to vote all shares of common stock of the
Company beneficially owned in aggregate by the WCAS Shareholders in excess of
9.9% of the outstanding shares of common stock of the Company in proportion to
all votes cast by the other holders of common stock of the Company (as
determined by the Company in its sole discretion and excluding for these
purposes all shares of common stock beneficially owned by the WCAS
Shareholders).

         The WCAS Shareholders further irrevocably agree that they will not, and
will not permit any of their respective affiliates to, sell or otherwise
transfer, or agree to sell or otherwise transfer, directly or indirectly, any
shares of common stock of the Company beneficially owned by the WCAS
Shareholders, except: (1) to any person who agrees in writing to be bound by the
terms of this Agreement; (2) to any person or group who, after giving effect to
such sale or transfer, would beneficially own shares of common stock
representing in the aggregate 9.9% or less of the outstanding shares of common
stock of the Company, calculated on a fully-diluted basis; (3) pursuant to a
firm commitment, underwritten distribution to the public, registered under the
Securities Act of 1933, as amended, in which the WCAS Shareholders use their
reasonable best efforts to effect as wide a distribution of such shares of
common stock as is reasonably practicable; (4) pursuant to Rule 144 of the
General Rules and Regulations of the Securities Act of 1933; and (5) pursuant to
a

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tender or exchange offer or merger made by the Company or recommended by the
Company's board of directors to the Company's stockholders.

                                    Sincerely,

                                    WELSH, CARSON, ANDERSON & STOWE
                                         VIII, L.P.
                                         By WCAS VIII Associates, L.L.C.,
                                         its General Partner

                                    By:     /s/ JONATHAN RATHER
                                            ------------------------------------
                                            Name:     Jonathan Rather
                                            Title:    Managing Member

                                    WCAS CAPITAL PARTNERS III, L.P.
                                         By WCAS CP III Associates, L.L.C.,
                                         its General Partner

                                    By:     /s/ JONATHAN RATHER
                                            ------------------------------------
                                            Name:     Jonathan Rather
                                            Title:    Managing Member

                                    WCAS INFORMATION PARTNERS, L.P.

                                    By:     /s/ JONATHAN RATHER
                                            ------------------------------------
                                            Name:     Jonathan Rather
                                            Title:    General Partner
                                                      Attorney-in-Fact

                                   ---------------------------------------------
                                   KENNETH MELKUS

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                                   PATRICK J. WELSH
                                   RUSSELL L. CARSON
                                   BRUCE K ANDERSON
                                   THOMAS E. MCINERNEY
                                   ROBERT A. MINICUCCI
                                   LAWRENCE B. SORREL
                                   ANTHONY J. DE NICOLA
                                   PAUL B. QUEALLY
                                   ANDREW M. PAUL
                                   LAURA VANBUREN
                                   PRISCILLA A. NEWMAN

                                   By:      /s/ JONATHAN RATHER
                                            ------------------------------------
                                            Name:       Jonathan Rather
                                            Individual and
                                            Attorney-in-Fact

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                                     TRUST U/A DATED 11/26/84
                                          FBO ERIC WELSH

                                     By:
                                             -----------------------------------
                                             Name:     Carol Ann Welsh
                                             Title:    Trustee

                                     TRUST U/A DATED 11/26/84
                                          FBO RANDALL WELSH

                                     By:
                                             -----------------------------------
                                             Name:     Carol Ann Welsh
                                             Title:    Trustee

                                     TRUST U/A DATED 11/26/84
                                          FBO JENNIFER WELSH

                                     By:
                                             -----------------------------------
                                             Name:     Carol Ann Welsh
                                             Title:    Trustee

Accepted as of the date
 first above mentioned

SPECTRASITE HOLDINGS, INC.

By: /s/ STEPHEN H. CLARK
    -------------------------------------
    Stephen H. Clark
    President and Chief Executive Officer

                                       4<PAGE>
                                                                    EXHIBIT 10.7

                              TERMINATION AGREEMENT
                              TO THE THIRD AMENDED
                      AND RESTATED STOCKHOLDERS' AGREEMENT

         Agreement dated as of October 4, 2002, by and among SpectraSite
Holdings, Inc., a Delaware corporation (the "COMPANY"), and the parties set
forth on the signature pages hereto terminating the Third Amended and Restated
Stockholders' Agreement, dated as of April 20, 1999, as amended by Amendment No.
1, dated as of November 20, 2000, Amendment No. 2, dated as of December 14,
2000, and Amendment No. 3, dated as of March 31, 2001 (as so amended, the
"STOCKHOLDERS' AGREEMENT"). Unless otherwise defined herein, capitalized terms
shall have such meanings ascribed to them in the Stockholders' Agreement.

         WHEREAS, the parties hereto desire to terminate the Stockholders'
Agreement; and

         WHEREAS, Section 18 of the Stockholders' Agreement provides that the
Stockholders' Agreement may be amended or modified by an instrument in writing
signed by the Company and holders of at least 60% of the voting power of the
Capital Stock held by Stockholders; and

         WHEREAS, Section 18 of the Stockholders' Agreement requires the consent
of any adversely affected party in order to amend the Stockholders' Agreement in
a manner that limits the right of any party to designate members of the
Company's Board of Directors (the "BOARD"); and

         WHEREAS, the parties to this Agreement constitute at least 60% of the
voting power of the Capital Stock held by Stockholders and include all parties
having a right to designate members of the Board.

         NOW, THEREFORE, in consideration of the premises and the mutual
covenants and agreements contained herein, the parties hereby agree as follows:

         1. Termination of the Stockholders' Agreement. The Stockholders'
Agreement is hereby terminated in its entirety. From and after the date hereof,
all rights and obligations of each party to the Stockholders' Agreement shall be
terminated without further action by any party and the Stockholders' Agreement
shall have no further force or effect.

         2. Counterparts. This Agreement may be executed by one or more of the
parties hereto on any number of separate counterparts and all such counterparts
shall be deemed to be one and the same instrument. Each party hereto confirms
that any facsimile copy of such party's executed counterpart of this Agreement
(or its signature page thereof) shall be deemed to be an executed original
thereof.

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         3. Governing Law. This Agreement shall be governed by, and enforceable
under, and construed in accordance with the laws of the State of Delaware,
without regard to principles of conflicts of law of such state.

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         IN WITNESS WHEREOF, each of the parties hereto has executed this
Agreement, as of the day and year first above written.

                                    SPECTRASITE HOLDINGS, INC.

                                    By: /s/ STEPHEN H. CLARK
                                       -----------------------------------------
                                       Stephen H. Clark
                                       President and Chief Executive Officer

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                                    WELSH, CARSON, ANDERSON & STOWE VIII, L.P.

                                    By:   WCAS VIII Associates, L.L.C.,
                                          its General Partner

                                    By: /s/ JONATHAN RATHER
                                       -----------------------------------------
                                        Name:    Jonathan Rather
                                        Title:   Managing Member

                                    WCAS CAPITAL PARTNERS III, L.P.

                                    By:   WCAS CP III Associates, L.L.C.,
                                          its General Partner

                                    By: /s/ JONATHAN RATHER
                                       -----------------------------------------
                                        Name:    Jonathan Rather
                                        Title:   Managing Member

                                    WCAS INFORMATION PARTNERS, L.P.

                                    By: /s/ JONATHAN RATHER
                                       -----------------------------------------
                                        Name:    Jonathan Rather
                                        Title:   General Partner
                                                 Attorney-in-Fact

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                                    --------------------------------------------
                                                   KENNETH MELKUS

                                    PATRICK J. WELSH
                                    RUSSELL L. CARSON
                                    BRUCE K. ANDERSON
                                    THOMAS E. MCINERNEY
                                    ROBERT A. MINICUCCI
                                    LAWRENCE B. SORREL
                                    ANTHONY J. DE NICOLA
                                    PAUL B. QUEALLY
                                    ANDREW M. PAUL
                                    LAURA VANBUREN
                                    PRISCILLA A. NEWMAN

                                    By: /s/ JONATHAN RATHER
                                       -----------------------------------------
                                        Name:    Jonathan Rather
                                        Title:   Individually and
                                                 Attorney-in-Fact

                                    TRUST U/A DATED 11/26/84 FBO ERIC WELSH

                                    By:
                                       -----------------------------------------
                                        Name:    Carol Ann Welsh
                                        Title:   Trustee

                                    TRUST U/A DATED 11/26/84 FBO RANDALL WELSH

                                    By:
                                       -----------------------------------------
                                        Name:    Carol Ann Welsh
                                        Title:   Trustee

                                    TRUST U/A DATED 11/26/84 FBO JENNIFER WELSH

                                    By:
                                       -----------------------------------------
                                        Name:    Carol Ann Welsh
                                        Title:   Trustee

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                                    SBC TOWER HOLDINGS LLC

                                    By: /s/ GREGORY L. GIBSON
                                       -----------------------------------------
                                        Name:    Gregory L. Gibson
                                        Title:   Vice President and Manager

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                                    TOWER PARENT CORP.

                                    By: /s/ TIMOTHY M. DONAHUE
                                       -----------------------------------------
                                        Name:    Timothy M. Donahue
                                        Title:   President

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                                    CIBC WG ARGOSY MERCHANT FUND 2, L.L.C.

                                    By: /s/ ANDREW R. HEYER
                                       -----------------------------------------
                                        Name:    Andrew R. Heyer
                                        Title:   Managing Member

                                    CO-INVESTMENT MERCHANT FUND 3, LLC

                                    By: /s/ ANDREW R. HEYER
                                       -----------------------------------------
                                        Name:    Andrew R. Heyer
                                        Title:   Managing Member

                                    CARAVELLE INVESTMENT FUND, L.L.C.

                                    By:  Caravelle Advisors, L.L.C.,
                                    its Investment Manager and Attorney-in-Fact

                                    By: /s/ ANDREW R. HEYER
                                       -----------------------------------------
                                        Name:    Andrew R. Heyer
                                        Title:   Managing Member

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                                    WHITNEY EQUITY PARTNERS, L.P.

                                    By:   Whitney Equity Partners, LLC,
                                          its General Partner

                                    By:
                                       -----------------------------------------
                                        Name:    Michael R. Stone
                                        Title:   Managing Member

                                    J.H. WHITNEY III, L.P.

                                    By:   J.H. Whitney Equity Partners III, LLC,
                                          its General Partner

                                    By:
                                       -----------------------------------------
                                        Name:    Michael R. Stone
                                        Title:   Managing Member

                                    WHITNEY STRATEGIC PARTNERS III, L.P.

                                    By:   J.H. Whitney Equity Partners III LLC,
                                          its General Partner

                                    By:
                                       -----------------------------------------
                                        Name:    Michael R. Stone
                                        Title:   Managing Member

                                    WHITNEY MEZZANINE FUND, L.P.

                                    By: Whitney Group, LLC,
                                        its General Partner

                                    By:
                                       -----------------------------------------
                                        Name:    Michael R. Stone
                                        Title:   Managing Member

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                                    /s/ STEPHEN H. CLARK
                                    --------------------------------------------
                                    STEPHEN H. CLARK

                                    /s/ DAVID P. TOMICK
                                    --------------------------------------------
                                    DAVID P. TOMICK

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