Exhibit 4.10


                CONSENT AND AGREEMENT TO SBCW REGISTRATION RIGHTS
                                       AND
               AMENDMENT TO EXISTING REGISTRATION RIGHTS AGREEMENT


         Reference  is  made  to  that  certain   Second  Amended  and  Restated
Registration   Rights  Agreement  dated  April  20,  1999,  as  amended,   among
SpectraSite  Holdings,  Inc. (the "Company"),  the WCAS Purchasers,  the Whitney
Purchasers,  the CIBC Purchasers and the Additional  Purchasers,  including TPC,
each as  defined  therein  (such  agreement  being  referred  to  herein  as the
"Existing  Registration  Rights  Agreement" and the Purchasers  thereunder being
referred to as the "Existing  Holders").  Capitalized  terms used herein and not
otherwise  defined  shall have the  meanings  assigned  to them in the  Existing
Registration Rights Agreement.

         SBC Transaction

         The Existing Holders understand that the Company currently  anticipates
entering  into a  joinder  agreement  with SBC  Tower  Holdings,  LLC  ("SBCW"),
pursuant to which SBCW would become a party to the Existing  Registration Rights
Agreement  and  entitled  to the  benefits  of a holder  of  "Restricted  Stock"
thereunder.  Pursuant  to  Section  13(e) of the  Existing  Registration  Rights
Agreement,  the Existing  Holders named below (who  collectively  represent more
than 60% of the  voting  power of the  Restricted  Stock  and  Management  Stock
currently  outstanding)  consent to the granting of the  foregoing  registration
rights by the Company.  The Existing  Holders  named below also agree that their
execution of this consent shall be effective to modify the Existing Registration
Rights  Agreement  pursuant  to  Section  13(e)  thereof  as if their  signature
appeared on the SBCW  joinder  agreement  itself,  and that if  requested by the
Company they will  execute the joinder  agreement  itself,  so long as the terms
thereof are consistent in all material respects with the terms described in this
letter.

         Trimaran Investment

         Pursuant  to  Section  13(e)  of  the  Existing   Registration   Rights
Agreement,  the Existing  Holders named below (who  collectively  represent more
than 60% of the  voting  power of the  Restricted  Stock  and  Management  Stock
currently outstanding) agree that:

         (A) the  first  clause  of the last  sentence  of  Section  4(c) of the
         Existing  Registration  Rights Agreement be amended in its entirety and
         replaced by the following:

         "Except  as  provided  in  this   paragraph  (c)  or  pursuant  to  any
         registration  rights set forth in the  Registration  Rights  Agreement,
         dated as of November  20,  2000,  by and among the Company and Trimaran
         Fund II, L.L.C.,  Trimaran Capital,  L.L.C., Trimaran Parallel Fund II,
         L.P., CIBC Employee Private Equity Fund (Trimaran)

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         Partners and CIBC World  Markets  Ireland  Limited  (the  "Trimaran
         Registration  Rights Agreement"),";

         (B) clause  (i) of the first  paragraph  of  Section 6 of the  Existing
         Registration Rights Agreement concerning an "underwriter's  cutback" be
         amended in its entirety and replaced by the following:

         "(i)  first,  the  securities  the  Company  proposes  to  sell  or the
         securities  proposed  to be sold  pursuant  to  Sections  4 or 5 of the
         Trimaran Registration Rights Agreement,";

         (C) clause  (ii) of the first  paragraph  of Section 6 of the  Existing
         Registration  Rights Agreement be amended to include therein the shares
         of Common Stock that are  requested  to be included in any  "piggyback"
         registration pursuant to the Registration Rights Agreement, dated as of
         November  20,  2000,  by and among the  Company and  Trimaran  Fund II,
         L.L.C., Trimaran Capital, L.L.C., Trimaran Parallel Fund II, L.P., CIBC
         Employee Private Equity Fund (Trimaran) Partners and CIBC World Markets
         Ireland Limited.

The Existing Holders named below also agree that their execution of this consent
shall be effective to modify the Existing Registration Rights Agreement pursuant
to Section 13(e) thereof.

                                       2

<PAGE>



                CONSENT AND AGREEMENT TO SBCW REGISTRATION RIGHTS
                                       AND
               AMENDMENT TO EXISTING REGISTRATION RIGHTS AGREEMENT


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

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


By:  /s/ Lawrence B. Sorrel
     ------------------------------
         Name: Lawrence B. Sorrel
         Title: Chairman of the Board

TOWER PARENT CORP. (Nextel)


By:   /s/ Steven M. Shindler
     ------------------------------
         Name: Steven M. Shindler
         Title: Director

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


By:   /s/ Steven A. Flyer
     -----------------------------
         Name: Steven A. FLyer
         Title: Attorney-in-Fact


J.H. WHITNEY III, L.P.

By: J.H. Whitney Equity Partners III, L.L.C.,
Its General Partner


By:   /s/ Daniel J. O'Brien
     ----------------------------
         Name: Daniel J. O'Brien
         Title: Managing Member