<PAGE>   1
                                                                    EXHIBIT 10.2

                                    LEASE AND
                                    SUBLEASE




                                  by and among


          SBC      TOWER HOLDINGS LLC, a Delaware limited liability company, for
                   itself and as Agent for the SBC GROUP,


                                       and


            SBC WIRELESS, LLC, a Delaware limited liability company,
                                  as Guarantor,


                                       and


                             SOUTHERN TOWERS, INC.,


                                       and


                           SPECTRASITE HOLDINGS, INC.,
                                  as Guarantor



                             Dated December 14, 2000



<PAGE>   2

<TABLE>
<S>                                                                                                            <C>
                                TABLE OF CONTENTS

                                                                                                               Page

SECTION 1. Definitions............................................................................................1
SECTION 2. Sublease Documents....................................................................................13
SECTION 3. Subleased Property....................................................................................14
SECTION 4. Existing Subleases and Colocation Agreements..........................................................19
SECTION 5. Reserved Space........................................................................................20
SECTION 6. Permitted Use.........................................................................................22
SECTION 7. Access................................................................................................22
SECTION 8. Term.  23
SECTION 9. Withdrawal............................................................................................23
SECTION 10. Rent and SBC Leaseback Charge........................................................................24
SECTION 11. Condition of the Sites and Obligations of TowerCo....................................................25
SECTION 12. Requirements for Alterations; Title to Alterations; Addition of Equipment; Work
            on the Site..........................................................................................28
SECTION 13. Damage to the Site, Tower or the Improvements........................................................30
SECTION 14. Space Subtenants; Interference.......................................................................32
SECTION 15. Taxes and Assessments................................................................................33
SECTION 16. Utilities............................................................................................35
SECTION 17. Governmental Permits.................................................................................35
SECTION 18. No Liens.............................................................................................36
SECTION 19. Condemnation.........................................................................................38
SECTION 20. Waiver of Subrogation; Indemnity.....................................................................39
SECTION 21. Subordination and Attornment.........................................................................40
SECTION 22. Environmental Covenants..............................................................................41
SECTION 23. Insurance............................................................................................44
SECTION 24. Right of Substitution; Right of First Refusal........................................................46
SECTION 25. Assignment and Subletting............................................................................49
SECTION 26. Estoppel Certificate.................................................................................51
SECTION 27. Holding Over.........................................................................................51
SECTION 28. Rights of Entry and Inspection.......................................................................52
SECTION 29. A Party's Right to Act for the Other Party; SBC Set-Off Right........................................52
SECTION 30. Defaults and Remedies................................................................................53
SECTION 31. Quiet Enjoyment......................................................................................58
SECTION 32. No Merger............................................................................................58
SECTION 33. Broker and Commission................................................................................58
SECTION 34. Recording of Memorandum of Ground Lease..............................................................59
SECTION 35. Purchase Options.....................................................................................59
SECTION 36. Net Lease............................................................................................62
SECTION 37. Compliance with Specific FCC Regulations.............................................................62
SECTION 38. Guaranty.............................................................................................63
SECTION 39. Tax Indemnities......................................................................................66
SECTION 40. General Provisions...................................................................................74
</TABLE>

<PAGE>   3


                               LEASE AND SUBLEASE


         THIS  LEASE  AND  SUBLEASE  is made and  entered  into this 14th day of
December,  2000 (this  "Sublease"),  by and among SBC WIRELESS,  LLC, a Delaware
limited  liability  company  ("Wireless  Guarantor"),  SBC TOWER HOLDINGS LLC, a
Delaware  limited  liability  company (for itself and as Agent for the SBC Group
Members whose names are set forth on Exhibit D hereof or which become parties to
this  Sublease  after the date hereof,  "SBC"),  SPECTRASITE  HOLDINGS,  INC., a
Delaware corporation ("TowerCo Parent"),  and SOUTHERN TOWERS, INC., an indirect
wholly-owned  subsidiary  of TowerCo  Parent and a Delaware  corporation  (doing
business in Oklahoma as Southern Towers of Delaware, Inc.) ("TowerCo").

         In   consideration   of  the  premises  and  other  good  and  valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
Parties to this Sublease agree as follows:

SECTION 1. Definitions.

         For purposes of this Sublease, the following capitalized terms have the
following respective meanings:

                  "Additional  Rent" has the meaning  set forth in Section  3(i)
hereof.

                  "Affiliate"  of a  Person  means  any  Person  which,  whether
         directly or indirectly,  Controls, is Controlled by, or is under common
         Control with the subject Party.

                  "After-Tax  Basis"  has  the  meaning  set  forth  in  Section
         39(a)(3)(i) hereof.

                  "Agreement  to  Sublease"  means  the  Agreement  to Lease and
         Sublease,  by and among TowerCo Parent,  TowerCo, and the SBC Group, as
         amended.

                  "Alterations"   means  the  construction  or  installation  of
         Improvements   on  any  Site  or  any  part  thereof   after  the  Site
         Commencement  Date  for  such  Site,  or the  alteration,  replacement,
         modification  or addition to all or any  component  of a Site after the
         Site   Commencement   Date  for  such  Site,   whether   Severable   or
         Non-Severable.

                  "Assumed   Rate"  has  the   meaning   set  forth  in  Section
         39(a)(1)(v) hereof.

                  "Available  Space" means, as to any Site, a Tower location,  a
         portion  of the  Land,  a  portion  of the  Improvements  or any  other
         portion,  space or area of such Site that is available  for sublease by
         TowerCo to any Space Subtenant  (including SBC and SBC  Affiliates,  in
         such  capacity) and all rights  appurtenant  to such portion,  space or
         area.

                  "Award" means any amounts paid,  recovered or  recoverable  as
         damages, compensation or proceeds by reason of any taking on account of
         a Taking,  including all amounts paid  pursuant to any  agreement  with
         such entity  which has been made in  settlement  or under threat of any
         such  action or  proceeding,  less the  reasonable  costs and  expenses
         incurred in collecting such amounts.

<PAGE>   4
                                                                               2

                  "Build to Suit Agreement" means the Agreement to Build to Suit
         dated as of the date hereof by and among SBC Wireless, LLC, SpectraSite
         Communications, Inc. and SpectraSite Holdings, Inc.

                  "Capital  Stock"  means:  (i) in the  case  of a  corporation,
         corporate stock; (ii) in the case of an association or business entity,
         any  and  all  shares,  interests,  participations,   rights  or  other
         equivalents  (however designated) of corporate stock; (iii) in the case
         of  a  partnership  or  limited  liability   company,   partnership  or
         membership  interests (whether general or limited);  and (iv) any other
         interest or participation that confers on a Person the right to receive
         a share of the  profits and losses of, or  distributions  of assets of,
         the issuing Person.

                  "Cash Flow"  means,  as to any  Person,  the  earnings  before
         interest expense,  depreciation,  amortization and taxes of such Person
         and its Subsidiaries on a consolidated basis,  determined in accordance
         with GAAP.

                  "Claims"   means  any   claims,   demands,   actions,   suits,
         proceedings,   disbursements,  judgments,  damages,  penalties,  fines,
         losses,   liabilities,   costs  and  expenses,   including   reasonable
         attorneys' fees and amounts paid in settlements.

                  "Code"  means the Internal  Revenue  Code of 1986,  as amended
         from time to time.

                  "Colocation Agreements" means any existing agreements pursuant
         to  which  any  SBC  Affiliate   shares  as  of  the  applicable   Site
         Commencement   Date  any  Site  with  other   providers   of   wireless
         telecommunications   services,   local  public  safety   organizations,
         governmental   entities  such  as  post  offices  and  law  enforcement
         organizations,   and  operators  of  remote   monitoring   systems  for
         commercial  purposes,  and to  which  such  SBC  Affiliate  is a party.
         Colocation    Agreements    with   other    providers    of    wireless
         telecommunications  services  have  been  (in the  case of the  Initial
         Sites) or will be prior to the applicable  Site  Commencement  Date (in
         the  case of other  Sites),  disclosed  to  TowerCo  in the  disclosure
         schedules delivered pursuant to the Agreement to Sublease.

                  "Commonly Assessed Taxes" has the meaning set forth in Section
         15(c).

                  "Communications Equipment" means, as to any Site, transmitting
         and/or  receiving  equipment  and  other  equipment  installed  at  the
         Reserved Space (as to SBC or any SBC Affiliate) or any Available  Space
         (as to a Space  Subtenant),  which is or will be necessary in providing
         current and future wireless communication  services,  including without
         limitation,  switches,  antennas,  microwave dishes, panels,  conduits,
         flexible  transmission lines, cables,  radio,  amplifiers,  filters and
         other transmission or communications  equipment (including interconnect
         transmission  equipment,  transmitter(s),  receiver(s) and accessories)
         and such other equipment and associated software as may be necessary in
         order  to  provide  such  wireless  communication  services,  including
         without  limitation,  voice or  data.  Communications  Equipment  shall
         include any existing, replaced and upgraded Communications Equipment.

<PAGE>   5
                                                                               3

                  "Communications  Facility" means, as to any Site, the Reserved
         Space (as to SBC or an SBC  Affiliate) or any Available  Space (as to a
         Space Subtenant),  together with the applicable SBC Affiliate's or such
         Space Subtenant's Improvements.

                  "Control"  means the  ownership,  directly or  indirectly,  of
         sufficient  voting shares of an entity,  or otherwise  the  possession,
         directly or  indirectly,  of the power to direct or cause the direction
         of the  management  and  policies  of an entity,  whether  through  the
         ownership of voting securities, by contract or otherwise.

                  "CPI" means the Consumer Price Index for all Consumers,  U.S.,
         City Average  (1982-84 = 100) All Items Index,  published by the Bureau
         of Labor  Statistics,  United States  Department  of Labor.  If the CPI
         shall cease to be compiled and published at any time during the term of
         this  Sublease,  but a  comparable  successor  index  is  compiled  and
         published by the Bureau of Labor  Statistics,  United States Department
         of Labor,  the adjustments to the SBC Leaseback  Charge provided for in
         Section  10, if any,  and any other  adjustments  provided  for in this
         Sublease which are based on the CPI Change shall be computed  according
         to such successor index,  with appropriate  adjustments in the index to
         reflect any differences in the method of computation  from the CPI. If,
         at any time  during the term of this  Sublease,  neither  the CPI nor a
         comparable  successor  index is compiled and published by the Bureau of
         Labor  Statistics,  the index for "all items" compiled and published by
         any other branch or department of the federal  government shall be used
         as a basis for  calculation of the  CPI-related  adjustments to the SBC
         Leaseback Charge provided for in this Sublease, and if no such index is
         compiled  and  published  by any branch or  department  of the  federal
         government,  the  statistics  reflecting  cost of living  increases  or
         decreases,   as   applicable,   as  compiled  by  any   institution  or
         organization  or  individual  generally  recognized  as an authority by
         financial and insurance institutions shall be used.

                  "CPI Change" means an increase or decrease, if any, (expressed
         as a positive or negative  percentage)  in the most recently  published
         CPI as of  January 1  immediately  preceding  the  commencement  of the
         applicable Site Term Year (the "Index Date"), from the CPI published as
         of January 1 immediately preceding the Index Date.

                  "Date of  Taking"  means the  earlier  of the date upon  which
         title to applicable Site, or any portion  thereof,  subject to a Taking
         is  vested  in  the  condemning  authority,  or  the  date  upon  which
         possession of such Site or portion  thereof is taken by the  condemning
         authority.

                  "Default Notice" has the meaning given to such term in Section
         3(h) hereof.

                  "Effective Date" means the date of this Sublease, as set forth
         in the caption of the Sublease.

                  "Emergency"  has the  meaning  given to such  term in  Section
         29(b) hereof.

                  "Estimated Cost" has the meaning given to such term in Section
         17(f) hereof.
<PAGE>   6
                                                                               4

                  "Existing  Sublease"  means,  with  respect  to any Site,  any
         sublease, license, lease or other agreement for use of a Tower location
         and other  space on such Site  between  a SBC  Affiliate  and any other
         Person that is in effect as of the applicable  Site  Commencement  Date
         excluding that certain Master Site Agreement  dated  September 30, 2000
         between  SBC and the  "User(s)",  which  shall  be  considered  to be a
         sublease  of the  Reserved  Space by the  applicable  Sublessor  to the
         "User(s)" and shall be subject to the restrictions contained in Section
         25 of this Sublease.

                  "Fair  Market  Value"  as to any Site,  means the fair  market
         sales  value of such Site that  would be  obtained  in an  arm's-length
         transaction  between an informed and willing  buyer and an informed and
         willing seller, under no compulsion,  respectively,  to buy or sell the
         Site in question.

                  "FAA" means the United States Federal Aviation Administration.

                  "FCC" means the United States Federal Communications
Commission.

                  "Federal Depreciation Deductions" has the meaning set forth in
         Section 39(a)(1)(ii) hereof.

                  "Federal Income Tax Benefits"  means the Federal  Depreciation
         Deductions and the federal  income tax deductions  described in Section
         39(a)(1)(iii) hereof.

                  "Ground  Lease" means,  as to a Leased Site, the ground lease,
         easement,  license or other  agreement,  pursuant  to which a Sublessor
         holds a leasehold  interest,  leasehold  estate,  easement,  license or
         other real property interest.

                  "Ground  Lessor"  means,  as to a Leased Site,  the  "lessor",
         "landlord",  "licensor",  or similar  Person  under the related  Ground
         Lease.

                  "Ground  Rents"  means,  as to any Site,  all rents,  fees and
         other  charges  payable by a Sublessor  to the Ground  Lessor under the
         Ground Lease for such Site.

                  "Improvements"  means,  as to  each  Site,  (i)  one  or  more
         concrete  equipment pads or raised  platforms  capable of accommodating
         exterior cabinets,  electrical service and access for the placement and
         servicing of SBC's or a SBC Affiliate's and, if applicable,  each Space
         Subtenant's  Improvements;  (ii) buildings,  huts, shelters or exterior
         cabinets;  (iii)  generators and associated fuel tanks;  (iv) grounding
         rings  (other  than  those  for  SBC's or a SBC  Affiliate's  equipment
         shelters);  (v) fencing;  (vi) signage;  (vii)  connections for utility
         service up to the meter; (viii) hardware  constituting a tower platform
         to hold  SBC's or a SBC  Affiliate's  and,  if  applicable,  each Space
         Subtenant's  Communications  Equipment;  (ix) access road improvements;
         (x)  common  shelters,  if any;  (xi) all  lighting  systems  and light
         monitoring  devices;  and  (xii)  such  other  equipment,  alterations,
         replacements,  modifications,  additions,  and  improvements  as may be
         installed on or made to all or any component of a Site  (including  the
         Land  and  the  Tower).  Improvements  do  not  include  Communications
         Equipment.
<PAGE>   7
                                                                               5

                  "Inclusion" means the inclusion in the income of any SBC Group
         Member of any  amount  realized  in  connection  with the  transactions
         effected by this Sublease or related  documents  other than the amounts
         described in Section 39(a)(1)(iv) hereof.

                  "Initial  Site" has the meaning set forth in the definition of
"Site."

                  "Investment  Grade" means  outstanding  senior  unsecured debt
         securities rated BBB or higher by Standard & Poor's or Baa or higher by
         Moody's.

                  "Land" means, as to each Site, the land constituting a portion
         of such Site,  together with all easements and other rights appurtenant
         thereto.

                  "Laws" means all federal,  state, county,  municipal and other
         governmental constitutions,  statutes,  ordinances, codes, regulations,
         resolutions,  rules,  requirements  and  directives  and all decisions,
         judgments,  writs,  injunctions,  orders, decrees or demands of courts,
         administrative  bodies  and  other  authorities   (including,   without
         limitation, the FAA and FCC) construing any of the foregoing.

                  "Leased  Site"  means a Site as to which a  Sublessor  holds a
         leasehold  interest,  leasehold  estate,  easement,  license  or  other
         possessory  interest in the Land which is part of such Site pursuant to
         a Ground Lease.

                  "Liens"  means,  as to each Site,  an interest or a claim by a
         Person other than SBC or any of its  Affiliates,  whether such interest
         or claim is based on the common law,  statute or  contract,  including,
         without  limitations,   liens,  charges,   Claims,  leases,   licenses,
         Mortgages,   conditional   agreements,   title  retention   agreements,
         preference,  priority  or other  security  agreements  or  preferential
         arrangements  of any  kind,  reservations,  exceptions,  encroachments,
         covenants,  conditions,  restrictions  and other title  exceptions  and
         encumbrances  affecting  all or any  part of the  Land,  the  Tower  or
         Improvements thereof.

                  "Market  Capitalization"  means,  as to any Person,  as of any
         date of determination,  either (i) the number of issued and outstanding
         shares of such  Person's  Capital  Stock (as set forth in such Person's
         most recent filings with the U.S.  Securities and Exchange  Commission)
         multiplied  by the closing price of the Capital Stock of such Person on
         any  exchange  on which such stock is listed or (ii) in the case of any
         Person  as to which the  information  specified  in  clause  (i) is not
         available,  the  total  market  value  of the  equity  of such  Person,
         determined by a commercially reasonable appraisal process.

                  "Mortgage" means, as to any Site, any mortgage, deed to secure
         debt, deed of trust,  trust deed or other conveyance of, or encumbrance
         against,  the Land or  Improvements  on such Site as  security  for any
         debt, whether now existing or hereafter arising or created.

                  "Mortgagee" means, as to any Site, the holder of any Mortgage,
         together with the heirs, legal representatives, successors, transferees
         and assigns of the holder.
<PAGE>   8
                                                                               6

                  "NDA" means a  non-disturbance,  subordination  and attornment
         agreement executed between a Mortgagee and TowerCo.

                  "Net Worth" means, with respect to a Person,  the total assets
         minus the total  liabilities of such Person and its  Subsidiaries  on a
         consolidated basis, as determined in accordance with GAAP.

                  "Non-Conforming  Alterations"  has the  meaning  given to such
         term in Section 3(i) hereof.

                  "Nonseverable" shall mean, with respect to any Alteration, any
         Alteration that is not a Severable Alteration.

                  "Non-TowerCo  Taxes"  has the  meaning  set  forth in  Section
15(c).

                  "Option  Purchase  Price Amount"  means,  with respect to each
         Site,  the fixed  purchase  price  for such  Site in the event  TowerCo
         exercises  its purchase  option with respect  thereto  under Section 35
         hereof as specified in Exhibit A.

                  "Option  Trigger  Window" has the meaning set forth in Section
35(a).

                  "Owned  Site"  means a Site with  respect to which a Sublessor
         owns fee simple title in the Land which is part of the Site.

                  "Party"  means  each  of  the  SBC  Group  Members,   Wireless
         Guarantor, TowerCo and TowerCo Parent, as appropriate.  "Parties" means
         the SBC Group Members,  Wireless Guarantor,  TowerCo and TowerCo Parent
         together.

                  "Permitted  Liens"  has the  meaning  given  to  such  term in
Section 18(a).

                  "Permitted  Subleasehold  Mortgage" means a mortgage,  deed of
         trust,  trust  deed,  deed  to  secure  debt  or  other  like  security
         instrument  for the  benefit  of a  Permitted  Subleasehold  Collateral
         Assignee.

                  "Permitted  Subleasehold  Pledge" means a pledge or collateral
         assignment  as  security  for any  indebtedness  for the  benefit  of a
         Permitted Subleasehold Collateral Assignee.

                  "Permitted Subleasehold Collateral Assignee" means a holder of
         (i) a collateral assignment of this Sublease, the Agreement to Sublease
         or the Build to Suit Agreement,  and/or (ii) a mortgage, deed of trust,
         trust deed, deed to secure debt or other like security  instrument with
         respect to TowerCo's leasehold and subleasehold interests in all or any
         portion of the Sites, pursuant to that certain Credit Agreement,  dated
         as of April 20, 1999,  as amended,  among  SpectraSite  Communications,
         Inc., as borrower,  SpectraSite  Holdings,  Inc.,  as  guarantor,  CIBC
         Oppenheimer  Corp.,  Credit  Suisse First Boston and the other  parties
         thereto, as the same may be amended, supplemented,  extended, restated,
         refinanced or refunded (collectively, the "Credit Agreement"), or that
<PAGE>   9
                                                                               7

         will be a recipient or beneficiary of a pledge or collateral assignment
         by  TowerCo  of  TowerCo's  interests  hereunder  or  the  holder  of a
         mortgage,  deed of trust, trust deed, deed to secure debt or other like
         security   instrument   with   respect  to  TowerCo's   leasehold   and
         subleasehold  interests  in all or any  portion  of the Sites  that has
         assets  at the  time of the  execution  of the  Permitted  Subleasehold
         Pledge or Permitted Subleasehold  Mortgage, as applicable,  of not less
         than $2  billion,  and is:  (i) a  national  bank;  (ii) a  commercial,
         national or state savings bank or trust company; (iii) an investment or
         merchant  bank;  (iv) a foreign  bank  authorized  to make loans in the
         United  States;  (v)  a  charitable  foundation;  (vi)  a  real  estate
         investment fund; (vii) an insurance  company;  (viii) a credit company;
         (ix) a pension or retirement  fund or a fund which,  in turn, is funded
         substantially  by a  pension  or  retirement  fund;  (x) a real  estate
         investment trust; (xi) a venture capital firm; (xii) a mortgage banking
         house; (xiii) an international bank or investment company; or (xiv) any
         other institutional  lender performing lending functions similar to any
         of the foregoing.  Notwithstanding  the foregoing,  in no event shall a
         Permitted Subleasehold Collateral Assignee be a SBC Competitor.

                  "Permitted Transferee" means: (i) a Person who has outstanding
         debt that is  Investment  Grade;  (ii) with  respect  to a  transaction
         involving  twenty  percent  (20%) or more of all Sites now or hereafter
         subject to this Sublease and less than forty percent (40%) of all Sites
         now or hereafter subject to this Sublease, a Person reasonably believed
         by SBC to have a current Net Worth or Market Capitalization of at least
         $50  million or Cash Flow for the last full  fiscal year of such Person
         of at least $10 million;  (iii) with respect to a transaction involving
         forty  percent  (40%) or more of all Sites now or hereafter  subject to
         this  Sublease and less than eighty  percent (80%) or more of all Sites
         now or hereafter subject to this Sublease, a Person reasonably believed
         by SBC to have a current Net Worth or Market Capitalization of at least
         $250  million or Cash Flow for the last full fiscal year of such Person
         of at  least  $50  million;  or  (iv)  with  respect  to a  transaction
         involving  eighty  percent  (80%) or more of all Sites now or hereafter
         subject to this Sublease, a Person reasonably believed by SBC to have a
         current Net Worth or Market  Capitalization of at least $500 million or
         Cash Flow for the last full fiscal year of such Person of at least $100
         million.

                  "Permitted  TowerCo  Transferee"  means:  (i) a Person who has
         outstanding  debt that is  Investment  Grade;  (ii) with  respect  to a
         Transfer of the Subleased  Property  involving more than twenty percent
         (20%) but less than forty  percent  (40%) of all Sites now or hereafter
         subject to this Sublease,  a Person  reasonably  believed by TowerCo to
         have a  current  Net Worth or Market  Capitalization  of at least  $100
         million or Cash Flow for the last full fiscal year of such Person of at
         least $5 million;  (iii) with  respect to a Transfer  of the  Subleased
         Property  involving  forty  percent  (40%) or more of all  Sites now or
         hereafter  subject to this Sublease and less than eighty  percent (80%)
         or more of all Sites  now or  hereafter  subject  to this  Sublease,  a
         Person  reasonably  believed  by TowerCo to have a current Net Worth or
         Market  Capitalization  of at least  $250  million or Cash Flow for the
         last full fiscal year of such Person of at least $50  million;  or (iv)
         with  respect  to a Transfer  of the  Subleased  Property  or any other
         transaction of the types referred to in Section 25(a), involving eighty
         percent  (80%) or more of all Sites now or  hereafter  subject  to this
         Sublease, a Person reasonably believed by TowerCo to have a current Net
         Worth or Market  Capitalization  of at least $500  million or Cash Flow
         for the last full fiscal year of such Person of at least $100 million.
<PAGE>   10
                                                                               8

                  "Permitted  Use" means use of the  Subleased  Property of each
         Site for the  purposes  of: (i)  constructing,  installing,  operating,
         managing,  maintaining and marketing the Tower and Improvements thereof
         and making further  Improvements  to such Site as permitted  hereunder,
         and (ii) for further use of such Subleased Property by Space Subtenants
         (including SBC and SBC Affiliates  with respect to any Available  Space
         or Reserved Space), and the right to use by Space Subtenants (including
         SBC and SBC Affiliates  with respect to any Available Space or Reserved
         Space) of any portions of the Land, Tower and Improvements of each Site
         as  are  reasonably  necessary  for  operation  of  the  Communications
         Facilities of such Space Subtenants.

                  "Person"  means an  individual,  partnership,  joint  venture,
         limited liability company, association, corporation, trust or any other
         legal entity.

                  "Proceeds" means all insurance moneys recovered or recoverable
         by TowerCo or any Sublessor as compensation  for casualty damage to any
         Site (including the Tower and Improvements thereof).

                  "Reimbursable Cost" has the meaning given such term in Section
17(f) hereof.

                  "Rent" has the meaning set forth in Section 10(b).

                  "Reserved  Space" means,  as to each Site:  (i) the portion of
         the Land and  Improvements of such Site used by SBC or an SBC Affiliate
         as of the date of the applicable Site  Commencement  Date, or as may be
         used by SBC or a SBC  Affiliate  as "Reserved  Space"  pursuant to this
         Sublease, as reserved for the exclusive use and occupancy by SBC or any
         SBC Affiliate,  including without limitation,  MTSOs and other switches
         and SBC's  Improvements  located on the Land, but not including parking
         spaces and associated  loading docks (which  facilities shall be shared
         by SBC, SBC  Affiliates,  TowerCo and Space  Subtenants on an equitable
         basis);  (ii) the  portion  of the Tower of such Site used by SBC or an
         SBC Affiliate for  Communications  Equipment as of the applicable  Site
         Commencement  Date,  or as may be  used by SBC or an SBC  Affiliate  as
         "Reserved  Space"  pursuant  to  this  Sublease,  as  reserved  for the
         exclusive  use and  occupancy by SBC or any SBC  Affiliates,  including
         without limitation,  any antennas,  transmission lines,  amplifiers and
         filters located on the Tower;  and (iii) any and all rights pursuant to
         Section 5(b) and 24 and all appurtenant rights reasonably  inferable to
         permit  SBC's and the SBC  Affiliates'  full use and  enjoyment  of the
         Reserved  Space,   including  without  limitation,   the  appurtenances
         specifically described in Section 5, all in accordance with Section 5.

                  "Restoration"  means, as to a Site that has suffered  casualty
         damage, such restoration,  repairs,  replacements,  rebuilding, changes
         and  alterations,  including  the  cost of  temporary  repairs  for the
         protection of such Site,  or any portion  thereof,  pending  completion
         thereof,  required to restore the applicable  Site (including the Tower
         and  Improvements  thereon) to a condition which is at least as good as
         the condition which existed  immediately prior to such damage, and such
         other changes or alterations as may be reasonably  acceptable to SBC or
         the applicable Sublessor and TowerCo or required by Law.
<PAGE>   11
                                                                               9

                  "Right of First Refusal"  means the right of SBC,  exercisable
         in its sole  discretion,  to sublease for its own use or the use of any
         SBC Affiliate any Available Space from TowerCo pursuant to Section 24.

                  "Right of Substitution" means the right of SBC, exercisable in
         its sole  discretion,  to substitute  for its own use or the use of any
         SBC Affiliate the Reserved Space of any Site for an Available  Space on
         such Site by relocation of its Communications  Facility on such Site to
         such Available Space, all pursuant to Section 24.

                  "SBC" has the meaning given to such term in the preamble.

                  "SBC   Affiliates"   means,   collectively,   any   Sublessor,
         Affiliates of Wireless Guarantor, the SBC Group Members, and any Person
         in which Wireless  Guarantor  owns,  directly or  indirectly,  at least
         fifty  percent  (50%)  of the  Voting  Stock  of such  Person  or which
         Wireless Guarantor otherwise Controls.

                  "SBC Alteration" has the meaning set forth in Section 24(a).

                  "SBC  Competitor"  means any Person whose  revenues,  together
         with any of its Affiliate's revenues, generated from providing wireline
         local    exchange    carrier    or    wireless    telephone    provider
         telecommunications  services,  constitute at least twenty percent (20%)
         of the total consolidated revenues of such Person and its Affiliates.

                  "SBC Group" means  collectively,  SBC, Wireless  Guarantor and
         the SBC  Affiliates  whose names are set forth in the  signature  pages
         hereof and any SBC  Affiliate  which at any time becomes a  "Sublessor"
         hereunder in accordance with the provisions hereof.  Each member of the
         SBC  Group is herein a "SBC  Group  Member".  Solely  for  purposes  of
         Section 39, the term "SBC Group" shall  include each SBC Group  Member,
         the affiliated group of corporations and each member thereof within the
         meaning of Code  section 1504 of which any SBC Group Member is or shall
         become a member if such group shall have filed a  consolidated  return;
         if  applicable,  each member in any entity  classified as a partnership
         for federal  income tax purposes  and such entity  itself if and to the
         extent  such  entity is treated as the tax owner of any of the Sites or
         portions  thereof  or such  entity is a direct or  indirect  partner in
         another  entity  classified  as a  partnership  which is so treated (in
         either case,  an "SBC  Partnership");  and, if  applicable,  any entity
         owned by a SBC Group  Member  or an SBC  Partnership  that for  federal
         income tax  purposes  is  disregarded  as an entity  separate  from its
         owner.

                  "SBC's Improvements" means each of the following, in each case
         located on the Land portion of the Reserved Space,  installed by or for
         the  benefit  of SBC or any SBC  Affiliate  and  used by SBC or any SBC
         Affiliate:  (i) such Person's  Communications  Equipment;  and (ii) (v)
         equipment shelters,  equipment buildings, and other constructions,  (w)
         generators  and  associated  fuel tanks,  (x) grounding  rings for such
         Person's equipment shelters, (y) connections for utilities service from
<PAGE>   12

                                                                              10

         the  meter  to  such  Communications  Equipment,  and  (z)  one or more
         foundations,  concrete  equipment  pads or  raised  platforms  for such
         Communications   Equipment,    equipment   shelters,    buildings   and
         constructions.

                  "SBC Indemnitee" means SBC, SBC Affiliates, and the respective
         directors,  officers,  employees,  and agents of SBC or SBC  Affiliates
         (except TowerCo and any agents of TowerCo).

                  "SBC  Leaseback  Charge" has the meaning given to such term in
Section 10(b).

                  "SBC  Partnership" has the meaning set forth in the definition
of "SBC Group".

                  "Severable"  shall mean, with respect to any  Alteration,  any
         Alteration  that can be readily  removed from a Site or portion thereof
         without damaging it in any material  respect or without  diminishing or
         impairing the value, utility, useful life or condition that the Site or
         portion  thereof  would have had if such  Alteration  had not been made
         (assuming  the Site or portion  thereof  would have been in  compliance
         with this Sublease  without such  Alteration),  and without causing the
         Site or portion  thereof to become  "limited use  property"  within the
         meaning of Rev.  Proc.  76-30,  1976-2 C.B.  647.  Notwithstanding  the
         foregoing,  an  Alteration  shall not be  considered  Severable if such
         Alteration is necessary to render the Site or portion thereof  complete
         for its intended use by TowerCo (other than  Alterations  consisting of
         ancillary items of equipment of a kind customarily furnished by lessees
         of property comparable to the Site or portion thereof).

                  "Site"  means  any  site  now or  hereafter  subject  to  this
         Sublease,  including without limitation:  (i) any initial Site which is
         subject to this  Sublease as of the date hereof as described in Exhibit
         A (the  "Initial  Sites");  and (ii) any  Site  added to this  Sublease
         pursuant  to  a  Site  Designation  Supplement  with  respect  thereto.
         Reference to a Site shall include the Land, the Tower, the Improvements
         (excluding Severable  Alterations) and Non-Severable  Alterations,  but
         shall not include Communications Equipment thereon.

                  "Site  Commencement  Date" means the date on which the Term of
         this  Sublease  commences  as to such Site,  which shall be the date of
         this  Sublease  with  respect to the Initial  Sites and the date as set
         forth in the applicable Site Designation Supplement with respect to all
         other Sites.

                  "Site  Designation  Supplement"  means,  as  to  any  Site,  a
         supplement to this  Sublease,  in  substantially  the form of Exhibit B
         attached  hereto,  pursuant to which such Site is made  subject to this
         Sublease,  and the  subleased  portions  thereof added to the Subleased
         Property.  All  representations and warranties made by SBC with respect
         to a Site shall be deemed made as of the date such Site is made subject
         to this Sublease.

                  "Site  Expiration  Date" means,  (i) as to any Owned Site, the
         Site Expiration Outside Date and (ii) as to any Leased Site, the sooner
         to occur of one day  prior to the  expiration  of the  relevant  Ground
         Lease (as the same may be  extended  or renewed  pursuant  to the terms
         hereof, including Section 3(f) hereof), and the Site Expiration Outside
         Date.
<PAGE>   13
                                                                              11

                  "Site Expiration Outside Date" means, as to any Site, the date
         certain set forth in Exhibit A or the Site  Designation  Supplement  as
         the "Site Expiration Outside Date".

                  "Site Term  Year"  means,  as to each  Site,  the one (1) year
         period commencing on the Site Commencement  Date, and ending on the day
         immediately  preceding the first  anniversary of the Site  Commencement
         Date,  and each  succeeding one (1) year period during the term of this
         Sublease.

                  "Space Subtenant" means, as to any Site, any Person (including
         SBC and any SBC  Affiliate in respect of any Available  Space),  which:
         (i) is a "sublessee" under an Existing Sublease affecting such Site; or
         (ii) subleases,  licenses or otherwise  acquires from TowerCo the right
         to use Available Space on such Site.

                  "Space  Subtenant's  Improvements"  means,  as  to  any  Space
         Subtenant at any Site, such Space Subtenant's Communications Equipment,
         together  with  equipment  buildings,   equipment  shelters  and  other
         constructions  located on the Land of the Available  Space of such Site
         and owned by such Space Subtenant.

                  "Sublease"  means this Lease and  Sublease,  together with any
         and all Exhibits,  Schedules and  attachments  hereto,  as the same may
         hereafter  be modified  and  amended,  including,  without  limitation,
         pursuant to Site Designation  Supplements.  References to this Sublease
         in respect of a  particular  Site shall  include  the Site  Designation
         Supplement therefor;  and references to this Sublease in general and as
         applied to all Sites shall include all Site Designation Supplements.

                  "Sublease   Year"  means  each   succeeding  one  year  period
commencing on the date hereof.

                  "Subleased  Property" means each Site that is now or hereafter
         subject to this Sublease,  including the Land,  Tower and  Improvements
         thereof,   less  and  except  in  each  instance,   Space   Subtenant's
         Improvements,  and SBC's  Improvements  on such Site. The Parties agree
         that the Subleased  Property includes the Reserved Space which is being
         leased  back  to SBC  (for  itself  and  for  the  benefit  of the  SBC
         Affiliates) as hereinafter provided.

                  "Subleasehold Estate" means: (i) the rights, title,  interest,
         powers, privileges, benefits and options of TowerCo under this Sublease
         (whether as lessee of an Owned Site or as sublessee of a Leased  Site);
         and (ii) all of the right,  title and interest of TowerCo in and to the
         Sites  under this  Sublease  (whether  as lessee of an Owned Site or as
         sublessee of a Leased Site).

                  "Sublessor"  means,  as to each Site,  the SBC Affiliate  that
         either:  (i) owns fee simple title  thereto;  or (ii) holds a leasehold
         interest,  leasehold  estate,  easement,  license  or other  possessory
         interest therein pursuant to a Ground Lease.

                  "Sublessor  Alteration"  has the  meaning set forth in Section
24(a) hereof.
<PAGE>   14
                                                                              12

                  "Subsidiary"   means,   with   respect  to  any  Person,   any
         corporation,  partnership,  joint venture or other entity in which such
         Person owns,  either  directly or  indirectly,  more than fifty percent
         (50%) of the  outstanding  Capital  Stock or other  ownership or equity
         interests  therein,  as the case may be,  or has the power to direct or
         cause the direction of the management and policies thereof.

                  "Substantial  Portion of Site" means, as to a Site, so much of
         such Site (including the Land, Tower and Improvements  thereof,  or any
         portion  thereof) as, when subject to a Taking or damage as a result of
         a casualty,  leaves the untaken  portion  unsuitable  for the continued
         feasible and economic operation of such Site for the Permitted Use.

                  "Substitution" means the relocation by SBC or an SBC Affiliate
         on a Site, pursuant to its Right of Substitution.

                  "Taking" means,  as to any Site, any  condemnation or exercise
         of the power of eminent domain by any public authority vested with such
         power,  or any taking in any other  manner for public use,  including a
         private purchase, in lieu of condemnation, by a public authority vested
         with the power of eminent domain.

                  "Tax  Assumptions"  has  the  meaning  set  forth  in  Section
39(a)(1) hereof.

                  "Tax Claim" has the meaning set forth in Section 39(d) hereof.

                  "Tax   Indemnitee"  has  the  meaning  set  forth  in  Section
39(a)(3)(i) hereof.

                  "Tax  Indemnity  Notice"  has the meaning set forth in Section
39(a)(3)(i) hereof.

                  "Tax Loss" has the  meaning  set forth in Section  39(a)(3)(i)
hereof.

                  "Tax"  and  "Taxes"  has the  meaning  set  forth  in  Section
39(b)(1) hereof.

                  "Taxes and Assessments" means, as to each Site, any and all of
         the following levied, assessed or imposed upon, against or with respect
         to the  Site  (including  the  Reserved  Space),  any  part of the Site
         (including  the Reserved  Space),  or the use and occupancy of the Site
         (including  the Reserved  Space) at any time during the Term as to such
         Site:  (i) real  property  and personal  property ad valorem  taxes and
         assessments,  except  as  relates  specifically  to  SBC's  or any  SBC
         Affiliate's  Communications  Equipment  or  SBC's  Improvements;   (ii)
         charges made by any public or quasi-public  authority for  improvements
         or  betterments  related to the Site (other  than SBC's  Improvements);
         (iii) sanitary taxes or charges,  sewer or water taxes or charges; (iv)
         any tax levied,  assessed or imposed upon or against the Rent  reserved
         hereunder or upon SBC's or an SBC  Affiliates'  interest in the Site or
         this Sublease  (other than income or franchise  taxes or any future tax
         which is established in lieu of income or franchise taxes); and (v) any
         other   Governmental   or   quasigovernmental   impositions,   charges,
         encumbrances,   levies,  assessments,  fees  or  taxes  of  any  nature
         whatsoever  related to the Site,  whether  general or special,  whether
         ordinary or  extraordinary,  whether foreseen or unforeseen and whether
         payable in installments  or not,  except as it relates  specifically to
         Communications Equipment owned by SBC or any SBC Affiliate or the SBC's
         Improvements.
<PAGE>   15
                                                                              13

                  "Term" means:  (i) as to this Sublease,  the term set forth in
         Section  8(a) hereof;  and (ii) as to each Site,  the term during which
         this Sublease is applicable to such Site.

                  "Total  Sites"  means  the  aggregate  number  of Sites now or
         hereafter subject to this Sublease.

                  "Tower"  means a wireless  transmissions  tower  structure  or
structures on a Site.

                  "TowerCo" has the meaning set forth in the Preamble.

                  "TowerCo  Indemnitee" means TowerCo,  its Affiliates,  and the
         respective directors, officers, employees, and agents of TowerCo or its
         respective Affiliates.

                  "TowerCo Parent" has the meaning set forth in the Preamble.

                  "TowerCo  Work" has the  meaning  set forth in  Section  12(b)
hereof.

                  "Valuation  Process" has the meaning set forth in Section 3(i)
hereof.

                  "Voting  Stock" of any Person as of any date means the Capital
         Stock  of such  Person  that  is at the  time  entitled  to vote in the
         election of the Board of Directors of such Person.

                  "Wireless   Guarantor"  has  the  meaning  set  forth  in  the
Preamble.

                  "Withdrawal  Date" means the effective date of SBC's or an SBC
         Affiliate's  election to terminate its leaseback of the Reserved  Space
         pursuant to a Withdrawal Notice.

                  "Withdrawal  Notice"  means a  notice  given  by SBC or an SBC
         Affiliate pursuant to Section 9 exercising the Withdrawal Right.

                  "Withdrawal  Right" means the right of SBC or an SBC Affiliate
         to elect to terminate its leaseback of the Reserved  Space with respect
         to a Site as described in Section 9 hereof.

         Any  other  capitalized  terms  used in this  Sublease  shall  have the
respective meanings given to them elsewhere in this Sublease.

SECTION 2. Sublease Documents.

(a)  This Sublease  shall consist of the  following  documents,  as amended from
     time to time as provided herein:

     (i)  this Lease and Sublease;
<PAGE>   16
                                                                              14

     (ii) the  following  Exhibits,   which  are  incorporated  herein  by  this
          reference:

                Exhibit A        List of Sites Subject to Sublease
                Exhibit B        Form of Site Designation Supplement
                Exhibit C        Site Maintenance Obligations with respect to
                                 Subtenants' Communications Equipment
                Exhibit D        SBC Group Members Bound by the Sublease
                Exhibit E        Procedures For SBC to Process Tower Requests
                                  From TowerCo

     (iii)Schedules  to  the  Exhibits,   which  are   incorporated   herein  by
          reference; and

     (iv) such additional documents as are incorporated by reference.

(b) If any of the foregoing are  inconsistent,  this Sublease shall prevail over
the Exhibits, the Schedules and additional incorporated documents.

SECTION 3. Subleased Property.

(a) Subject to the terms and conditions of this Sublease,  each Sublessor hereby
lets,  leases and demises  unto  TowerCo,  and except as  otherwise  provided in
Sections 3(h) and 22(b), TowerCo hereby leases, takes and accepts from Sublessor
the Subleased Property of all of the Sites owned or leased by such Sublessor, in
its "AS IS" condition,  without any  representation,  warranty or covenant of or
from SBC or any SBC  Affiliate  whatsoever  as to the  condition  thereof or the
suitability thereof for any particular use, except as may be expressly set forth
herein or in the  Agreement  to  Sublease.  To SBC's  knowledge,  the Towers are
satisfactory in all material  respects for SBC's and its Affiliates'  continuing
use  consistent  with its  Permitted  Use of such  Towers.  Except  as set forth
herein,  TowerCo hereby acknowledges that neither SBC nor any Affiliate or agent
of SBC has made any representation or warranty, express or implied, with respect
to any of the Subleased Property,  or any portion thereof, or the suitability or
fitness  for  the  conduct  of  TowerCo's  business  or for any  other  purpose,
including the Permitted Use, and TowerCo further acknowledges that it has had or
by its execution and delivery of a Site  Designation  Supplement,  will have had
sufficient  opportunity  to inspect and approve the  condition of the  Subleased
Property of the Sites.

(b) Each Site in  addition to the  Initial  Sites shall be made  subject to this
Sublease by the execution  and delivery of a Site  Designation  Supplement  with
respect thereto between Sublessor and TowerCo.  SBC and TowerCo  acknowledge and
agree that this  Sublease is intended to constitute a single  sublease  covering
the Subleased  Property of all of the Sites and a single agreement  covering all
the Sites, and not a separate sublease and agreement covering individual Sites.

(c) This Sublease is a grant of a leasehold  interest in each Owned Site subject
to all matters affecting  Sublessor's  right,  title and interest in and to each
Owned Site (including without  limitation,  Existing Subleases and the interests
of third  parties  as to any Owned  Sites  that are  subject  to any  Colocation
Agreements); and, as to Leased Sites, this Sublease is a grant of a subleasehold
interest  in  each  Leased  Site  subject  to all  matters  affecting  title  to
Sublessor's  leasehold  interest,  leasehold estate or other possessory interest
<PAGE>   17
                                                                              15

therein (including without  limitation,  Existing Subleases and the interests of
third parties as to any Leased Sites that are subject to Colocation Agreements).

(d) TowerCo  hereby  acknowledges  that,  as to the  Subleased  Property of each
Leased Site,  this Sublease is a sublease by Sublessor  under the provisions of,
and is  subject  and  subordinate  to all of the terms and  conditions  of,  the
applicable  Ground Lease of such Leased Site.  As to any Leased Site,  Sublessor
shall not be deemed,  except as otherwise hereinafter expressly provided in this
clause (d), to have assumed any duty or  obligation  of the Ground  Lessor under
the applicable Ground Lease and shall not be liable or responsible in any manner
whatsoever  for any  failure of such  Ground  Lessor to perform any such duty or
obligation.  TowerCo  agrees that it will  promptly  pay or cause to be paid the
Ground Rent under each of the Ground  Leases of the Leased Sites during the Term
of this  Sublease  when such  payments  become due and payable and, in the event
TowerCo  fails to pay  Ground  Rent under any  Ground  Lease on a timely  basis,
TowerCo shall be responsible for any late charges,  fees or interest  payable to
the Ground  Lessor as a result  thereof.  Except as provided in Section  3(f) or
3(h),  TowerCo shall (and with respect to its activities on the Reserved  Space,
each  Sublessor  shall)  abide by,  comply in all respects  with,  and fully and
completely  perform all other terms,  covenants,  conditions,  and provisions of
each Ground Lease (including, without limitation, terms, covenants,  conditions,
and provisions relating to maintenance, insurance and alterations) as if TowerCo
were  the  "ground  lessee"  thereunder  and,  to the  extent  evidence  of such
performance  must be  provided  to the Ground  Lessor of the  applicable  Ground
Lease,  TowerCo shall provide such  evidence to  Sublessor;  provided,  however,
that, except as otherwise  hereinafter  provided in Section 3(f),  TowerCo shall
have no obligation,  and SBC shall retain the obligation, to provide or cause to
be provided any telephone or other  telecommunications  services  required to be
provided  under  the  Ground  Leases  as  in  effect  on  the  applicable   Site
Commencement Date or as otherwise  expressly agreed to by SBC. TowerCo shall not
engage in or permit  any  conduct  that  would:  (i)  constitute  a breach of or
default  under any  Ground  Lease;  or (ii)  result in the Ground  Lessor  being
entitled to terminate the  applicable  Ground Lease or to terminate  Sublessor's
right as ground lessee under such Ground Lease,  or to exercise any other rights
or remedies to which the Ground  Lessor may be entitled  for a default or breach
under the applicable Ground Lease. During the Term of this Sublease, and subject
to Section  3(f) below,  Sublessor  agrees to exercise  prior to the  expiration
thereof and in accordance  with the provisions of the  applicable  Ground Lease,
any and all renewal options existing as of the applicable Site Commencement Date
and as may be further extended or renewed by Sublessor  pursuant to the terms of
this Sublease, for any Leased Site under the Ground Leases of such Leased Sites;
provided,  however,  that Sublessor shall not be obligated to renew or otherwise
extend the term of any  applicable  Ground  Lease in the event  such  renewal or
extension  would extend the term of the Ground Lease beyond the Site  Expiration
Outside  Date for  such  Leased  Site  unless  TowerCo  requests  otherwise  and
Sublessor  consents to such request  (which  consent  shall not be  unreasonably
withheld).  The applicable  Sublessor shall (i) forward to the applicable Ground
Lessor all requests for consents and other notices relating to the Permitted Use
which  TowerCo  reasonably  wishes to  deliver  to such  Ground  Lessor and (ii)
deliver to TowerCo all material  notices and  communications  received  from the
applicable Ground Lessor.
<PAGE>   18
                                                                              16

(e) TowerCo  shall not be entitled to act as agent for, or  otherwise  on behalf
of,  SBC or any SBC  Affiliate  or to bind SBC or any SBC  Affiliate  in any way
whatsoever in connection with any Ground Lease or otherwise  except as otherwise
provided in this Section 3.

(f) With respect to any  negotiations  with a Ground Lessor for the extension or
terms of renewal of a Ground Lease  (other than a renewal or extension  pursuant
to an option  contained  in such Ground  Lease which  Sublessor  is obligated to
exercise  pursuant  to  Section  3(d)),   TowerCo  shall,  in  cooperation  with
Sublessor,  at  TowerCo's  sole cost and  expense,  be  responsible  for and use
commercially  reasonable efforts to negotiate and obtain an extension or renewal
of the  Ground  Leases of the Leased  Sites on behalf of and for the  benefit of
Sublessor,  and Sublessor shall make commercially  reasonable  efforts to assist
TowerCo in obtaining such extension or renewal,  provided that such extension or
renewal  does not impose any  liability on  Sublessor  for which  TowerCo is not
responsible (or subsequently  agrees to be responsible)  under the terms of this
Sublease  during the Term as to each Site and that neither SBC nor any Sublessor
shall  have any  obligation  to  provide or cause to be  provided  telephone  or
telecommunications  services  pursuant to Section 3(d) of this  Sublease  during
such extension or renewal. With respect to any amendment,  renewal, extension or
other change to the Ground Lease desired by TowerCo  during the term pursuant to
this  Section 3, (i)  Sublessor  shall be entitled to consent to any such change
(such  consent  not  to be  unreasonably  withheld)  and  (ii)  subject  to  the
foregoing,  Sublessor  shall execute any such amendment,  renewal,  extension or
change  within  ten  (10)  days of its  receipt  thereof  from  TowerCo  without
condition and shall bear any and all costs  associated  with its review.  In the
event TowerCo  determines that it is unable or deems it undesirable to negotiate
the terms of renewal or extension of the Ground Lease  directly  with the Ground
Lessor, Sublessor may attempt to negotiate such renewal or extension and TowerCo
shall reimburse Sublessor for its reasonable  out-of-pocket expenses relating to
such negotiation  unless TowerCo exercises its termination right provided in the
following sentence within the applicable time period. If Sublessor completes the
foregoing  negotiations for such extension or renewal,  the Site Expiration Date
shall be  extended  to the Site  Expiration  Outside  Date set forth in the Site
Designation  Supplement  provided,  however,  that if in  connection  with  such
renewal or extension Sublessor,  without the approval of TowerCo,  agrees to any
increase  in Ground  Rent  over the  then-current  Ground  Rent or agrees to any
revenue  sharing in excess of existing  revenue  sharing  arrangements,  TowerCo
shall have the option,  exercisable within thirty (30) days of receipt of notice
of the extension or renewal,  of terminating its subleasehold  interests in such
Site as of the date the  Ground  Lease  would have  expired  had  Sublessor  not
extended or renewed  such Ground  Lease.  If  Sublessor  or TowerCo is not able,
after using commercially reasonable efforts, to extend or renew any Ground Lease
in accordance  with this Section 3(f), then the Parties shall permit such Ground
Lease to expire on the applicable  expiration  date and this Sublease shall have
no further force and effect as to the  Subleased  Property of the Leased Site to
which such Ground Lease applies.  Each of TowerCo and TowerCo Parent agrees that
neither it, nor any of its Affiliates,  may seek to obtain or hold, any interest
in any Ground Lease or its  underlying fee interest that is superior or prior to
Sublessor's  interests in such Ground Lease.  SBC or an SBC Affiliate shall have
the right to acquire the fee simple  interest in the Site from the Ground Lessor
whereupon  such Site shall be deemed an Owned Site, in which event TowerCo shall
have a leasehold interest in such Owned Site. Except as provided in this Section
3(f), or as TowerCo may  otherwise  agree or direct,  during the Term  Sublessor
shall not take any action to amend or supplement any Ground Lease, other than to
<PAGE>   19
                                                                              17

exercise renewals as expressly provided herein which each Sublessor covenants to
do as provided  above.  In addition to the foregoing,  Sublessor  agrees that it
shall use its good faith  efforts to cooperate  with  TowerCo's  exercise of (or
right to exercise  any of) its rights  under this  Sublease  with respect to the
Ground Lease and the Ground Lessor, including,  without limitation,  pursuant to
this Section 3.

(g)  Subject to Section 18 and Section 25,  Sublessor's  right to sell,  convey,
transfer, assign or otherwise dispose of Sublessor's interest in and to any Site
(including  Sublessor's  interest in and to the Subleased Property of such Site)
shall be unrestricted.

(h) Notwithstanding anything to the contrary contained herein, SBC represents to
TowerCo that, as of the applicable Site Commencement Date, each Ground Lease for
a Leased  Site is or will be in full force and effect  and  Sublessor  is not or
will not be in default under any such Ground Lease in any material  respect as a
result of  Sublessor's  (or any  present  or  former  SBC  Affiliate's)  acts or
omissions.  Each Sublessor shall perform any  obligations  under and comply with
the  terms  of each of the  Ground  Leases,  but  only if such  obligations  are
expressly  reserved to  Sublessor  for its  performance  under the terms of this
Sublease. Upon receipt by Sublessor of any notice of default or notice of an act
or  omission  which  could with the  passing of time and/or the giving of notice
constitute  an event of default  under a Ground Lease or  non-compliance  with a
term of a Ground  Lease  (the  "Default  Notice"),  SBC shall,  within  five (5)
business  days after  receipt of the Default  Notice or such  shorter time as is
reasonably  necessary  to avoid a  termination  of such  Ground  Lease,  provide
TowerCo with a copy of the Default  Notice.  If such  default or  non-compliance
with a term of a Ground  Lease is caused  by  TowerCo  or any  Space  Subtenant,
TowerCo  shall,  and shall  cause the  applicable  Space  Subtenant  to, cure or
otherwise remedy such default or noncompliance. Notwithstanding anything in this
Sublease to the contrary, unless an obligation under a Ground Lease is expressly
reserved  under this  Sublease  for  performance  by a  Sublessor,  any  default
referred to in the Default  Notice shall  constitute a default by TowerCo  under
this Sublease.

(i) Unless an event of default by TowerCo shall have occurred and be continuing,
TowerCo, at its own cost and expense, may from time to time make, subject to the
requirements of Section 12, such Alterations  that are not required  pursuant to
Section  11(a) as  TowerCo  may deem  desirable  in the  proper  conduct  of its
business,  so long  as (i)  such  Alteration  shall  not  disrupt  or  otherwise
adversely  affect  SBC's  or any SBC  Affiliate's  Permitted  Use of the Site or
portion  thereof and is made in accordance  with the  requirements  set forth in
Section 12 hereof, (ii) such Alteration shall not result in any material respect
in (y) the  value of the Site or  portion  thereof  being  less  than the  value
thereof  immediately  prior to such Alteration,  or (z) the economic life of the
Site or portion thereof being less than the economic life of the Site or portion
thereof  immediately  prior to such Alteration,  (iii) such Alteration shall not
cause the Site or portion  thereof to constitute  "limited use property"  within
the meaning of Rev. Proc. 76-30, 1976-2 C.B. 647, and (iv) no Alterations, taken
together or  separately,  shall fail to comply with the provisions of Rev. Proc.
75-21, 1975-1 C.B. 715 or 79-48, 1979-1 C.B. 529.

         Notwithstanding  anything to the  contrary  contained  in this  Section
3(i),  TowerCo,  at its own  cost  and  expense,  may  from  time  to time  make
Alterations (including,  without limitation,  Nonseverable Improvements that may
be required by Law),  which do not comply with subclause (iv) of the immediately
preceding  sentence   ("Non-Conforming   Alterations")  provided  that  (i)  the
Non-Conforming  Alterations  otherwise  satisfy the terms and provisions of this
<PAGE>   20
                                                                              18

Section 3(i), and (ii) the applicable Sublessor does not make TowerCo's proposed
Non-Conforming  Alterations  in  accordance  with the  remainder of this Section
3(i).  In the event that  TowerCo  desires to make  Non-Conforming  Alterations,
TowerCo shall submit written notice to the applicable  Sublessor describing such
proposed  Non-Conforming  Alterations in reasonable detail. Such Sublessor shall
elect whether to make or cause to be made, at such Sublessor's cost and expense,
the Non-Conforming  Alterations by written notice provided to TowerCo within ten
(10) days after  receipt of  TowerCo's  proposal  regarding  the  Non-Conforming
Alterations. Such Sublessor's failure to respond to TowerCo within such ten (10)
day  period  shall be deemed to be such  Sublessor's  election  not to make such
Non-Conforming  Alterations.  In the  event  such  Sublessor  elects to make the
Non-Conforming  Alterations  and such  Sublessor  and TowerCo agree on terms and
conditions,  including,  but not  limited to, the amount and timing of rent with
respect  to such  Non-Conforming  Alterations  ("Additional  Rent"),  then  such
Sublessor shall make the Non-Conforming Alterations in accordance with plans and
specifications,  and  according  to a time  schedule,  provided  by TowerCo  and
reasonably  acceptable  to such  Sublessor.  In the event  that  such  Sublessor
elects, or is deemed to have elected, not to make the Non-Conforming Alterations
or such  Sublessor  and TowerCo  shall not have agreed on terms and  conditions,
TowerCo may make such Non-Conforming  Alterations and,  notwithstanding anything
to the contrary  contained  in this  Sublease  (other than the other  conditions
contained in this Section 3(i)), title to the  Non-Conforming  Alterations shall
without  further act or instrument act or instrument  vest in TowerCo.  Upon the
expiration  or  earlier  termination  of this  Sublease  as to a Site  at  which
Non-Conforming Alterations have been made, the following provisions shall apply:
(i) if TowerCo has not  exercised  its option to purchase  such Site and TowerCo
has made any Non-Conforming  Alterations,  the applicable Sublessor may purchase
such  Non-Conforming  Alterations from TowerCo at a price equal to the then fair
market value of such Non-Conforming  Alterations,  (ii) if TowerCo has exercised
its option to purchase such Site, TowerCo shall purchase such Site at a purchase
price equal to the Option Purchase Price Amount, plus the then fair market value
of the Non-Conforming Alterations and/or Sublessor Alterations,  if any, made to
such Site,  and (iii) if TowerCo has not  exercised  its option to purchase such
Site, TowerCo has made Non-Conforming Alterations,  and the applicable Sublessor
does not purchase such  Non-Conforming  Alterations from TowerCo,  TowerCo shall
continue  to hold such  Non-Conforming  Alterations,  and all rent and any sales
proceeds  attributed  to such Site  thereafter  shall be  allocated  between the
applicable  Sublessor and TowerCo in accordance with their relative interests in
such  Site (as  determined  below).  In each of  subclauses  (i) and (ii) of the
immediately  preceding  sentence,  the  applicable  party shall pay the purchase
price in cash or immediately  available funds. In each of the subclauses (i) and
(ii),  the then  fair  market  value of the  Non-Conforming  Alterations  and/or
Sublessor  Alterations  shall equal the excess of the then fair market  value of
such Site including such Non-Conforming Alterations and/or Sublessor Alterations
over  the   estimated   then  fair  market  value  of  such  Site  without  such
Non-Conforming   Alterations  and/or  Sublessor   Alterations.   The  applicable
Sublessor and TowerCo shall  attempt,  in good faith,  to agree on the then fair
market value of the Non-Conforming  Alterations and/or Sublessor Alterations (or
the relative interests of the applicable  Sublessor and TowerCo,  if applicable)
or,  alternatively,  shall  attempt,  in good faith,  to agree on an independent
qualified  appraiser  to  determine  such fair market  value and the fair market
values of the Non-Conforming  Alterations  and/or the Sublessor  Alterations (or
the relative interests of the applicable  Sublessor and TowerCo, if applicable).
Absent  agreement on value or on an appraiser  within thirty (30) days,  each of
such  Sublessor and TowerCo shall identify an  independent  qualified  appraiser
<PAGE>   21
                                                                              19

within ten (10) days  thereafter.  If either party fails to appoint an appraiser
within  such ten (10) day period,  the  appraiser  appointed  by the other party
shall alone  determine  such fair market value (or relative  interests).  If two
appraisers  are  appointed  and such  appraisers  cannot  agree on the then fair
market value (or the relative interests of the applicable Sublessor and TowerCo,
if applicable),  such appraisers  shall identify a third  independent  qualified
appraiser who shall  determine the then fair market value of the  Non-Conforming
Alterations and/or Sublessor  Alterations and the relative fair market values of
the Non-Conforming Alterations and/or the Sublessor Alterations (or the relative
interests of Sublessor and TowerCo, if applicable) (collectively, the "Valuation
Process");  provided that if such two appraisers cannot agree on the identity of
such third  appraiser  within ten (10) days after the  appointment of the second
appraiser,  either party may apply to the American  Arbitration  Association for
the appointment of such appraiser.  If TowerCo  exercises its option to purchase
the Site,  the fair market value of the  Non-Conforming  Alterations  and/or the
fair market value of the Sublessor  Alterations shall be paid to the party which
made such Alterations.

SECTION 4.        Existing Subleases and Colocation Agreements.

(a) Without limiting the generality of Section 3, TowerCo expressly acknowledges
that,  as to each Site,  this  Sublease  is subject  to all  Existing  Subleases
affecting such Site, including, without limitation,  Existing Subleases executed
prior to the  applicable  Site  Commencement  Date  pursuant  to any  Colocation
Agreement.  In respect of each Site,  by  execution  of this  Sublease or a Site
Designation Supplement the applicable Sublessor does transfer, assign and convey
over unto TowerCo, for the Term of this Sublease in respect of such Site, all of
its rights,  title and interest as  "sublandlord" or "sublessor" in, to or under
any  Existing  Subleases  affecting  such Sites and does hereby  delegate all of
Lessor's duties,  obligations and responsibilities  under the Existing Subleases
to TowerCo for periods occurring from and after the applicable Site Commencement
Date. TowerCo does hereby assume and agree to pay and perform all of the duties,
obligations,  liabilities and  responsibilities of Sublessor as "sublandlord" or
"sublessor"  under the Existing  Subleases  affecting each Site arising from and
after the date of the Site  Designation  Supplement for such Site and commencing
on the Site Commencement Date for such affected Site,  TowerCo shall receive all
rents  payable  thereunder  for  periods  occurring  from  and  after  the  Site
Commencement Date.

(b) From time to time,  SBC shall give TowerCo  written  notice of the intent of
third  parties to  Colocation  Agreements  to occupy any  Available  Space,  and
promptly following receipt of such notice,  TowerCo shall cooperate with SBC and
the applicable  third party so as to facilitate such third party's  occupancy of
such Available Space on commercially reasonable terms.

(c) TowerCo shall, and does hereby agree to, indemnify,  defend and hold the SBC
Indemnitees  harmless from, against and in respect of any and all Claims,  paid,
suffered,  incurred or sustained by any SBC Indemnitee and in any manner arising
out of,  by  reason  of,  or in  connection  with  any  failure  of the  duties,
obligations, liabilities and responsibilities of a Sublessor as "sublandlord" or
"sublessor" under any of the Existing Subleases  affecting each Site and arising
from and  after  the Site  Commencement  Date for  such  Site,  to be fully  and
completely  performed pursuant to the Existing  Subleases,  except to the extent
caused by an SBC Indemnitee.
<PAGE>   22
                                                                              20

(d) Unless  TowerCo  exercises the purchase  option with respect to a Site under
Section 35 hereof,  the  assignment by each Sublessor to TowerCo of the Existing
Subleases in respect of each Site shall automatically terminate and expire, such
Existing Subleases  (together with any Space Subtenant sublease which has a term
extending  beyond the  expiration  of the Term as permitted  under Section 24(c)
hereof or, in the case of a  termination  due to an event of default by TowerCo,
as to which a  non-disturbance  agreement  has been  entered  into  pursuant  to
Section 21(c)) shall automatically be (or be deemed) reassigned or assigned,  as
the case may be, to each  Sublessor or its designee,  and each  Sublessor or its
designee shall accept such reassignment or assignment,  as the case may be, upon
the  expiration  of the Term of, or earlier  termination  of,  this  Sublease in
respect of such Site.

SECTION 5.        Reserved Space.

(a) TowerCo and each Sublessor  expressly  acknowledges that, the Reserved Space
of each Site shall, at all times during the Term of this Sublease,  be deemed to
be leased or  subleased  to  TowerCo  pursuant  hereto  and  leased  back to the
applicable  Sublessor  pursuant  hereto for the exclusive  possession and use by
such Sublessor (or the SBC Affiliate  which conducts its wireless  activities at
the  Reserved  Space)  whether or not such  Reserved  Space is now or  hereafter
occupied. As an appurtenance to, and a part of, the Reserved Space of each Site,
each Sublessor (for the benefit of SBC or any SBC Affiliate) also reserves:  (i)
the right of  ingress  to and egress  from the  entire  Site,  and access to the
entire Tower and all  Improvements to such Site and Tower (including any and all
easements),  at such  times (on a 24-hour,  seven (7) day per week basis  unless
otherwise limited by the Ground Lease or other  restrictions of record that have
priority over the Sublease),  to such extent,  and in such means and manners (on
foot or by motor vehicle,  including trucks and other heavy  equipment),  as SBC
deems necessary or desirable in connection  with its or an SBC Affiliate's  full
use and enjoyment of the Reserved  Space,  including,  without  limitation,  the
construction,  installation, use, operation, maintenance, repair and replacement
of its Communications Facility thereon; and (ii) the right to use any portion of
the Subleased Property of a Site,  including the Land and Improvements  thereof,
for  purposes of  temporary  location  and storage of any  equipment  (including
Communications Equipment) and any part thereof in connection with performing any
repairs or replacements of such Person's Improvements;  provided,  however, that
such  storage  shall not have a  material  adverse  effect on Space  Subtenants'
Permitted Use.

(b) Subject to the  availability of Available  Space on the applicable  Tower at
the time of the  proposed  expansion,  SBC may at any time  expand the  Reserved
Space on up to three  hundred  (300)  Towers by the addition or  replacement  of
Communications Equipment on such Tower up to an additional fifteen percent (15%)
of the total  tower  loading  on such  Tower;  provided  that as a result of the
exercise of such  expansion  right SBC or the SBC Affiliate  which  occupies the
Reserved  Space shall not be entitled to occupy more than two (2)  platforms  on
any  Tower.  (For the  avoidance  of doubt,  if SBC or the SBC  Affiliate  which
occupies the Reserved  Space occupies one (1) platform at the time of expansion,
SBC or the SBC Affiliate  which occupies the Reserved Space may expand to occupy
only one additional platform, and if SBC or the SBC Affiliate which occupies the
Reserved Space occupies two (2) platforms at the time of such expansion,  SBC or
the SBC Affiliate which occupies the Reserved Space may expand on one or both of
the platforms it then occupies but may not expand to occupy an additional, third
platform.) SBC may exercise the foregoing  expansion right for itself or for the
use and benefit of any SBC Affiliate.
<PAGE>   23
                                                                              21

(c) Without limiting SBC's (and the SBC Affiliates')  rights under Section 24(a)
hereof and subject to the  availability  of  Available  Space on the  applicable
Tower at the time of the proposed expansion, SBC shall have the further right to
expand the amount of  equipment  on the Towers  beyond the first  three  hundred
(300) Towers, provided that SBC shall pay TowerCo as additional Leaseback Charge
$100 per month per panel/antenna or space equivalent of one  panel/antenna,  but
in no event in an amount to exceed  $1600 per  platform,  or if SBC  locates any
such  expanded  equipment on a platform  which is not already  occupied by SBC's
Communication  Equipment,  not to be less  than  $1200  per any such  additional
platform (except with respect to microwave dishes and related  equipment),  such
amount to be in addition to the SBC Leaseback  Charge due and payable to TowerCo
pursuant to Section 10. Such  amounts  shall  increase  each year after the date
hereof five percent (5%) per year, until the tenth anniversary of the applicable
Site  Commencement  Date and  thereafter  pursuant  to  Section  10(f).  SBC may
exercise the foregoing  expansion right for itself or for the use and benefit of
any SBC Affiliate.

(d)  Notwithstanding  anything to the  contrary  contained  herein,  the Parties
acknowledge and agree that the Reserved Space of each Site will include, without
limitation,  all  portions  of such Site  utilized  or occupied by SBC or an SBC
Affiliate as of the applicable Site Commencement Date for such Site for the use,
enjoyment,  operation or maintenance of Communications Facility on such Site for
the  Permitted  Use. If at any time  between the date hereof and the  applicable
Site Commencement Date, SBC or an SBC Affiliate elects to increase the amount of
equipment on a Tower on a Site,  then SBC shall have an option,  exercisable  at
its sole  discretion upon written notice to TowerCo prior to the applicable Site
Commencement  Date, to (i) count such Tower toward three hundred (300) Towers in
accordance  with  Section  5(b)  and  pay the  amount  of SBC  Leaseback  Charge
determined in  accordance  with Section 10(b) with respect to such Site, or (ii)
pay TowerCo,  the amount of SBC Leaseback  Charge  determined in accordance with
Section 5(c).

(e) The parties acknowledge and agree that antenna mounting hardware constitutes
a portion  of the  Improvements  and does not  constitute  part of the  Reserved
Space.  If, as to any Sites,  SBC or any SBC  Affiliate  desires to exercise its
Right  of   Substitution   pursuant  to  Section  24(b),  to  move  any  of  its
Communications Equipment on such Tower to any Available Space, and such exercise
would  require   relocation  of  the  existing  antenna  mounting   hardware  to
accommodate  such move,  TowerCo  shall move such antenna  mounting  hardware as
requested by SBC or such SBC  Affiliate,  unless (i) other Space  Subtenants are
sharing the same antenna mounting hardware, (ii) such relocation would adversely
affect  the  rights  of  other  Space  Subtenants  or  (iii)  TowerCo  otherwise
determines that such  relocation is not feasible or beneficial.  If TowerCo does
relocate SBC or such SBC Affiliate's  antenna  mounting  hardware in response to
the  exercise  of the Right of  Substitution,  SBC or such SBC  Affiliate  shall
reimburse  TowerCo  for  the  reasonable  costs  directly  attributable  to such
relocation.  If as  contemplated  by the  foregoing,  TowerCo does not or cannot
relocate the existing antenna mounting hardware, TowerCo shall, at its sole cost
and expense,  install  suitable  mounting  hardware at the location on the Tower
designated by SBC or the  applicable SBC  Affiliate,  so as to  accommodate  the
requested  relocation;  provided  that SBC or such SBC  Affiliate  shall  remain
responsible for the payment of all costs and expenses associated with moving its
antennas to the antenna mounting hardware supplied by TowerCo.
<PAGE>   24
                                                                              22

(f) If SBC or any SBC  Affiliate  desires to add or relocate any antennas to the
Tower  location of any Site,  the  provisions  of Sections  24(a)(i) and (a)(ii)
shall  apply.  Upon the  request of either  Party,  the Parties  shall  promptly
execute such instruments as may be reasonably  required to further evidence such
addition  or  relocation,  including  without  limitation  an  amendment  to the
applicable  Site  Designation  Supplement,  and shall cause such amendment to be
recorded at SBC's or such SBC Affiliate's  cost and expense,  unless the Parties
otherwise agree.

SECTION 6.        Permitted Use.

(a)      TowerCo shall use, and shall permit the use of, the Subleased  Property
of each Site only for the Permitted Use.

(b) TowerCo shall not use, or permit to be used,  the Subleased  Property of any
Site, or any portion thereof, by TowerCo,  any Person (other than SBC or the SBC
Affiliates)  or the  public in such  manner as might  reasonably  tend to impair
Sublessor's  title to or interest in such Site,  or any portion  thereof,  or in
such manner as might reasonably make possible a Claim or Claims of adverse usage
or adverse  possession by the public,  as such, or any Person (other than SBC or
an SBC Affiliate),  or of implied dedication of such Subleased Property,  or any
portion thereof. Nothing contained in this Sublease and no action or inaction by
SBC or an SBC Affiliate  shall be deemed or construed to mean that Sublessor has
granted to  TowerCo  any right,  power or  permission  to do any act or make any
agreement  that may create,  or give rise to or be the  foundation  for any such
right,  title,  interest,  lien,  charge or other encumbrance upon the estate of
Sublessor in any Site.

(c) SBC shall not use, or permit to be used,  the Reserved Space of any Site, or
any portion  thereof,  by SBC, any SBC  Affiliate,  any other Person (other than
TowerCo and Space  Subtenants) or the public in such manner as might  reasonably
tend to impair  TowerCo's right as a sublessor with respect to such Site, or any
portion thereof,  or in such manner as might reasonably make possible a Claim or
Claims of adverse  usage or adverse  possession  by the public,  as such, or any
Person (other than TowerCo and Space  Subtenants),  or of implied  dedication of
such Reserved Space, or any portion thereof.  Nothing contained in this Sublease
and no action or inaction by TowerCo  shall be deemed or  construed to mean that
TowerCo has  granted to SBC or any SBC  Affiliate  thereof  any right,  power or
permission to do any act or make any agreement that may create,  or give rise to
or be the foundation for any such right, title, interest,  lien, charge or other
encumbrance upon the leasehold estate of TowerCo in any Site.

SECTION 7.        Access.

         The Subleased Property of a Site includes,  as an appurtenance thereto,
a  non-exclusive  right for access to the  Subleased  Property of each Site on a
24-hour,  seven  (7) day per week  basis,  on foot or motor  vehicle,  including
trucks and other heavy  equipment,  for the  installation and maintenance of the
Tower  and  Improvements  thereof  and the  Communications  Facilities  of Space
Subtenants.  The  Parties  acknowledge  and agree  that the right to access  the
<PAGE>   25

                                                                              23

Subleased  Property of each Site, or any portion  thereof,  granted  pursuant to
this  Section 7 shall be  granted  to TowerCo  and its  authorized  contractors,
subcontractors,  engineers, agents, advisors, consultants,  representatives,  or
other persons authorized by TowerCo and, under TowerCo's direct supervision, and
to Space  Subtenants,  subject to any  restrictions  contained in the applicable
Ground Lease.

SECTION 8.        Term.

(a) The term of this  Sublease,  as to each  Site,  shall  commence  on the Site
Commencement  Date set forth in the Site  Designation  Supplement  with  respect
thereto and shall expire on the Site Expiration Date therefor.

(b) No surrender by TowerCo to the  Sublessor of the  Subleased  Property of any
Site or any portion thereof, prior to the expiration of the Term as to such Site
shall be valid or  effective  unless  agreed to and  accepted in writing by such
Sublessor,  and no act by such Sublessor,  other than such a written acceptance,
shall constitute an acceptance of any such surrender.

(c) As to any Site,  upon  expiration or earlier  termination  of this Sublease,
TowerCo  shall,  at its cost and expense  and upon  instructions  from SBC,  (i)
within a reasonable  period of time, but in no event less than thirty (30) days,
stop and cease,  and cause the Space  Subtenants  on such Site  (other  than any
Space  Subtenants  under an  Existing  Lease or under a  sublease  entered  into
pursuant  to  Section  24(c)  hereof  which has a term that  extends  beyond the
termination  or  expiration  of this  Sublease or as to which a  non-disturbance
agreement  has been entered into  pursuant to Section  21(c)) to stop and cease,
the operation of its Communications Facilities on such Site and shall remove all
of  TowerCo's  Severable  Alterations  from  such  Site and  restore  each  Site
substantially  to the condition it was in on the  applicable  Site  Commencement
Date, subject to the addition of any permitted  Non-Severable  Alterations.  Any
Severable  Alterations not removed by TowerCo within said 15-day period shall be
deemed  abandoned  by TowerCo and title  thereto  shall  automatically,  without
further action, vest in the Sublessor of such Site.

SECTION 9.        Withdrawal.

(a) Notwithstanding anything to the contrary contained herein, SBC will have the
Withdrawal Right for the benefit of itself or any SBC Affiliate,  exercisable in
respect of any Site on the tenth anniversary of the applicable Site Commencement
Date and on each five-year anniversary of such date thereafter.  To exercise any
such  Withdrawal  Right,  SBC shall give TowerCo written notice of such exercise
not less than ninety  (90) days,  in the case of the  exercise  of a  Withdrawal
Right in respect of less than twenty percent (20%) of all Sites now or hereafter
under this  Sublease  and one  hundred  eighty  (180)  days,  in the case of the
exercise of a Withdrawal Right in respect of twenty percent (20%) or more of all
Sites now or hereafter under this Sublease,  prior to any such  anniversary (the
"Withdrawal  Notice"). If SBC exercises the Withdrawal Right as to any Site, SBC
shall not be required to pay the SBC Leaseback  Charge with respect to such Site
for the period occurring after the Withdrawal Date and the Withdrawal Date as to
such Site shall be the date specified in the applicable  Withdrawal  Notice. Not
later than the Withdrawal  Date of any Site, SBC or the applicable SBC Affiliate
shall vacate the Reserved  Space of such Site if such Reserved Space is occupied
<PAGE>   26
                                                                              24

whereupon  SBC's or the  applicable  SBC  Affiliate's  sublease of such Reserved
Space  pursuant  hereto and SBC's or the  applicable  SBC  Affiliate's  right to
occupy and use the Reserved Space of such Site as a sublessee hereunder shall be
terminated.  At the request of either SBC or TowerCo,  the  appropriate  parties
shall enter into documentation, in form and substance reasonably satisfactory to
such parties, evidencing any withdrawal effected hereunder.

(b) In addition to and not in limitation of any right of SBC under Section 9(a),
SBC will  have  the  right,  exercisable  at any  time  during  the Term of this
Sublease,  to cease  occupying  the Reserved  Space of any Site,  and retain its
right to such Reserved Space and may permit a SBC Affiliate to occupy such Site,
so long as SBC  continues  to pay the SBC  Leaseback  Charge in  respect of such
Site.

SECTION 10.       Rent and SBC Leaseback Charge.

(a) TowerCo  shall  prepay Rent (other than  Additional  Rent) in respect of the
Subleased  Property of each Site,  for the entire Term on the Site  Commencement
Date for each Site. Such Rent shall be specifically  allocated to rental periods
as set forth on the applicable Site Designation  Supplement  (including Exhibits
thereto).  TowerCo shall pay Additional Rent in such time, manner and amounts as
determined  pursuant to Section  3(i)  hereof.  Each month during the Term as to
each Site,  SBC shall pay, or cause an SBC  Affiliate to pay, the SBC  Leaseback
Charge in respect of the  Reserved  Space for such Site which is subject to this
Sublease,  in advance on or prior to the tenth (10) day of such calendar  month,
beginning on the Site Commencement Date for such Site.

(b)      The following terms shall have the following definitions:

                  "Rent"  means,  as to any Site the  rental  amount  prepaid by
         TowerCo for the leasing of the Sites  pursuant to this  Sublease and as
         specified  in Exhibit A and any  Additional  Rent with  respect to such
         Site.

                  "SBC Leaseback  Charge" means, as to any Reserved  Space,  the
         monthly  rental  amount  payable to TowerCo  for the  leaseback  of the
         Reserved  Space on such Site to SBC pursuant to this Sublease  equal as
         to any Site in any Site Term Year,  an amount equal to $1,400 per month
         subject to an increase of the lesser of (x) the  applicable  CPI Change
         plus four  percent  (4%) or (y) five  percent  (5%) per year (but never
         less than zero percent (0%)) on each anniversary of the Effective Date.

(c)  TowerCo  shall pay upon demand a late  charge of five  percent  (5%) of any
amount  payable by TowerCo under the  provisions  of this Sublease  which is not
paid  within  ten (10) days after the date the same is due;  provided,  however,
that the late charge  shall not be assessed in respect of the first late payment
occurring in any Site Term Year.

(d) If the Site Commencement Date for any Site is a day other than the first day
of a calendar  month,  the applicable  SBC Leaseback  Charge for the period from
such Site  Commencement  Date through the end of the calendar month during which
such Site Commencement Date occurs shall be prorated on a daily basis, and shall
be included in the  calculation  of the SBC Leaseback  Charge for the first full
calendar  month of the  Term,  on the  first  day of the  first  calendar  month
following such Site Commencement Date.
<PAGE>   27
                                                                              25

(e) SBC shall pay upon  demand a late  charge  of five  percent  (5%) of any SBC
Leaseback  Charge  payable by SBC under the provisions of this Sublease which is
not within ten (10) days after the date the same is due; provided, however, that
the late  charge  shall not be  assessed  in respect  of the first late  payment
occurring in any Site Term Year.  Notwithstanding the foregoing, if SBC fails to
pay (or fails to cause to be paid) any portion of a SBC Leaseback Charge because
SBC, acting in good faith, reduced the amount of SBC Leaseback Charge payable to
TowerCo  due  to  a  mistaken  belief  that  it  was  entitled  to  Reimbursable
Maintenance  Expenses  under Section  29(a),  no late charge shall be payable in
respect thereof.

(f)  Notwithstanding  anything to the contrary  contained  herein,  if after the
tenth (10th)  anniversary of the  applicable  Site  Commencement  Date, the then
current SBC  Leaseback  Charge  payable to TowerCo  with  respect to any Site is
below the market rate  agreed upon by the Parties at the time of  determination,
then  such  SBC  Leaseback  Charge  shall  automatically  be  increased  on such
anniversary  and  on  each  anniversary  thereafter,  based  on the  CPI  Change
effective as of date of such  anniversary.  If, however,  the then SBC Leaseback
Charge  payable to TowerCo  with  respect to such Site is above the market rate,
then such SBC Leaseback  Charge shall be  automatically  reset at ninety percent
(90%)  of such  agreed  upon  market  rate  effective  as of such  tenth  (10th)
anniversary of the applicable Site  Commencement Date and shall increase on each
following  anniversary  at the then current  annual  market rate of increase for
comparable  properties.  Notwithstanding  anything  to  the  contrary  contained
herein,  the Parties shall agree as to the market rate not later than sixty (60)
days prior to such tenth anniversary of the applicable Site  Commencement  Date.
If the Parties are unable to agree upon the market rate,  then SBC shall have an
option,  exercisable  by written  notice to TowerCo,  to exercise its Withdrawal
Right in accordance with Section 9(a).

SECTION 11.       Condition of the Sites and Obligations of TowerCo.

(a) TowerCo  acknowledges  that, as between  TowerCo and SBC, in respect of each
Site,  TowerCo  has the  obligation,  right and  responsibility  to  repair  and
maintain  such Site  except as  otherwise  provided  herein,  including  without
limitation,  an  obligation  to monitor  each Tower to maintain  the  structural
integrity  of the Tower and the  ability  of the Tower to hold and  support  all
Communications  Equipment  then  mounted on the Tower,  in  accordance  with all
applicable Laws and standard industry practices. Subject to the other provisions
contained in this  Sublease,  TowerCo,  at its sole cost and expense,  except if
such cost or expense  arises out of a negligent  or wrongful  act or omission of
SBC or any SBC  Affiliates,  shall  monitor,  maintain and repair each Site such
that SBC and the SBC Affiliate and Space Subtenants may utilize such Site to the
extent permitted herein,  including,  without  limitation,  the markings on each
Tower and the structural integrity of each Tower. Installation,  maintenance and
repair of each Site must  comply  with all Laws  applied in a manner  consistent
with standard industry practices.  TowerCo assumes all  responsibilities,  as to
each Site, for any fines, levies,  and/or other penalties imposed as a result of
non-compliance   with  said   requirements  of  said  authorities   unless  such
non-compliance  occurs  on or prior to the Site  Commencement  Date for any such
Site (in which event SBC or the  applicable  SBC Affiliate  shall be responsible
for such  fines,  levies  and/or  other  penalties).  TowerCo  shall cause Space
Subtenants to maintain and repair all Communications  Equipment on each Site, in
accordance with the requirements of this Sublease  including without  limitation
<PAGE>   28

                                                                              26

as set forth in Exhibit C;  provided,  however,  that  nothing in this  Sublease
shall require  TowerCo to maintain SBC's or any SBC  Affiliate's  Communications
Equipment.  Without limiting the foregoing, TowerCo at its own cost and expense,
shall make (or cause to be made) all Alterations to the Sites as may be required
from time to time to meet in all respects the  requirements  of applicable  Laws
(regardless  of the Person  upon whom such  requirements,  by their  terms,  are
nominally imposed) except for the maintenance and repair work to be performed by
SBC in accordance with clause (c) of this Section 11.

(b) For each Site, TowerCo, at its sole cost and expense,  shall provide SBC all
necessary and  appropriate  information  requested by SBC for SBC to obtain (and
SBC will obtain  within a  reasonable  amount of time) all of the  certificates,
permits, and other approvals which may be required in connection with FCC or FAA
regulations.   TowerCo  shall  also  provide  SBC  all  appropriate  information
requested by SBC pertaining to any easements or consents which are required from
any third  parties with respect to the  operation  of such Site,  including  the
lighting  system  serving  such  Site,  SBC  shall  cooperate  with  TowerCo  in
connection  therewith,  as  contemplated by Section 17. Nothing in this Sublease
shall require TowerCo to provide any information necessary for SBC to obtain any
certificate,  permit or other approval  relating  specifically and only to SBC's
Communications  Equipment.  If,  as to any Site,  or any  portion  thereof,  any
certificate, permit, license, easement, or approval relating to the operation of
such Site is canceled,  expires, lapses, or is otherwise withdrawn or terminated
or, if TowerCo has breached its obligation  under this Section  11(b),  then SBC
shall  have the  right,  in  addition  to its other  remedies  pursuant  to this
Sublease,  at law, or in equity,  to take appropriate  action to remedy any such
noncompliance  and demand  reimbursement for any expenses incurred in connection
therewith  from  TowerCo,  and/or to  terminate  this  Sublease  as to such Site
subject to Sections 29 and 30.

(c)      The  following  provisions  shall  apply with  respect to the  lighting
systems  serving the Sites:

     (i)  SBC agrees to monitor the lighting  system  serving such Site and will
          notify (a) the appropriate FAA service office of any lighting  failure
          within  thirty  (30)  minutes of  discovering  such  failure,  and (b)
          TowerCo within sixty (60) minutes of discovering such failure.  In the
          event of any such  failure,  SBC agrees,  as soon as  practicable,  to
          begin a diligent  effort to repair the failed lighting on an Emergency
          basis,  and to notify TowerCo and the  appropriate  FAA service office
          upon  successful  completion  of the repair.  In  addition,  SBC shall
          maintain  and  repair  (within  any  applicable   time  periods  under
          applicable Laws) all lighting systems and light monitoring  devices at
          each Tower  (excluding  any  additional  devices  installed by TowerCo
          pursuant  to this clause (c))  notwithstanding  that such  systems and
          devices are being leased or subleased to TowerCo with each Tower.  SBC
          shall be reimbursed  for actual  reasonable,  out-of-pocket  costs and
          expenses incurred in connection with the maintenance and repair of the
          lighting  systems  and  monitoring  devices at each  Tower.  SBC shall
          periodically  provide  TowerCo  with an invoice for such costs  (which
          shall  include a copy of an  itemized  invoice  from any  third  party
          providing  services  or  materials  in  connection  with  the  work in
          question), which amount shall be paid by TowerCo within thirty (30)
<PAGE>   29
                                                                              27

          days of  TowerCo's  receipt of such  invoice.  TowerCo  shall have the
          right, at its own expense, to perform an audit of such actual costs by
          requesting  reasonable evidence of actual costs and expenses incurred.
          Notwithstanding the foregoing,  TowerCo's  obligation to reimburse SBC
          shall not  exceed  the  estimated  amount  which  TowerCo  would  have
          incurred in maintaining and repairing the lighting system serving such
          Site in accordance with TowerCo's customary procedures with respect to
          such  repair  and  maintenance,  such  estimates  to be  supported  by
          invoices or other  information  reasonably  satisfactory  to SBC.  SBC
          agrees to indemnify, defend and hold TowerCo harmless from and against
          any Claims  arising  out of or by reason of its failure to comply with
          the  monitoring,  notice and  repair  requirements  contained  in this
          Section  11(c)  unless  such  Claims  arise  out  of or by  reason  of
          TowerCo's gross  negligence or willful  misconduct.  At SBC's election
          and upon  reasonable  notice to TowerCo,  SBC may  require  TowerCo to
          assume the monitoring, maintenance and repair obligations with respect
          to the Tower lighting systems and the light monitoring  devices on all
          or a portion  of the  Sites  subject  to this  Sublease  at  TowerCo's
          expense, and TowerCo shall perform such obligations in accordance with
          the  standards  hereinabove  applicable to SBC's  performance  of such
          services.  If SBC makes such  election,  TowerCo  agrees to indemnify,
          defend and hold SBC harmless  from and against any Claims  arising out
          of or by reason of its failure to comply with the  monitoring,  notice
          and repair  requirements  contained in this Section  11(c) unless such
          Claims arise out of or by reason of SBC's gross  negligence or willful
          misconduct. Without in any way affecting SBC's obligations relating to
          lighting during the entire Term,  TowerCo and/or the Space  Subtenants
          shall  have  the  right,  at its  expense,  to  install  and  maintain
          equipment  for the  purpose  of  monitoring  (x) the  lighting  system
          serving  the Tower or the  Improvements  of each Site,  and/or (y) any
          device of SBC's used to  monitor  the  lighting  system  serving  each
          Tower.  At TowerCo's  election,  SBC shall (i) provide  TowerCo a data
          feed at cost and on other terms to be agreed upon (x) from SBC's alarm
          points for the lighting control  device(s) serving the Tower (it being
          understood  that these  devices will be leased or subleased to TowerCo
          with each Tower,  but that SBC will be responsible  for the repair and
          maintenance  of the  devices  and  their  wiring)  and  (y)  from  any
          additional devices which TowerCo wishes to install,  at TowerCo's sole
          cost and expense;  (ii) permit TowerCo access to the contact point box
          at each Tower where  TowerCo may install,  at TowerCo's  sole cost and
          expense,  its own  direct  links  to such  devices;  or  (iii)  permit
          TowerCo,  where available,  access to the contact point for each Tower
          through SBC's  regional  switching (it being  understood  that TowerCo
          shall be responsible  for providing its own dedicated  telephone lines
          to the  Site and that  these  monitoring  devices  will  generally  be
          subleased  to  TowerCo  with  each  Tower,  provided  that SBC will be
          responsible  for the repair and  maintenance  of the devices and their
          wiring up to the point of hand-off to TowerCo's  dedicated  lines). In
          addition,  at TowerCo's reasonable request SBC shall replace or permit
          TowerCo  to  replace  any tower  lighting  system  and tower  lighting
          monitoring  system that  experiences  recurring  maintenance or repair
          problems at  TowerCo's  cost and expense in  accordance  with a budget
          reasonably  approved  by SBC and  TowerCo.  In  addition to and not in
          limitation of Section 30(b), if SBC defaults under this Section 11(c),
          TowerCo,  in addition to its other remedies  pursuant to this Sublease
          (at law or in equity),  may elect to take appropriate action to notify
          the appropriate  FAA service office of any lighting  failure which SBC
          fails to  report,  or to repair or replace  any  lights or  monitoring
          equipment  which SBC fails to repair or replace within the time period
          required  under  applicable  Laws  and  invoice  SBC  for  its  actual
          reasonable, out-of-pocket costs and expenses.
<PAGE>   30
                                                                              28

(c) Without limiting  TowerCo's  obligations under this Section 11 and the other
provisions  of this  Sublease,  the  Parties  acknowledge  that  SBC and the SBC
Affiliates  are licensed by the FCC to provide  telecommunications  services and
that the Sites are used to provide  those  services.  Nothing  in this  Sublease
shall be construed to transfer control of any FCC  authorization  held by SBC or
the  SBC  Affiliates  to  TowerCo  or to  limit  the  right  of SBC  and the SBC
Affiliates to take all necessary  actions to comply with their obligations as an
FCC licensee or with any other legal obligations to which they are or may become
subject.

SECTION 12.    Requirements for Alterations;  Title to Alterations;  Addition of
Equipment; Work on the Site.

(a) All Alterations that are made to a Site (whether required or optional) shall
comply with the  requirements  of clauses (i),  (ii),  (iii) and (iv) of Section
3(i) hereof.  Subject to Section 3(i),  title to each  Alteration  shall without
further act or  instrument  vest in the  Sublessor of such Site and be deemed to
constitute a part of the Site and be subject to this Sublease  provided that any
such  Alteration  is required  pursuant  to Section 11 (a) or is a  Nonseverable
Alteration.  Title to all other  Alterations  shall  vest in  TowerCo.  Any such
Alteration may be removed by TowerCo,  at its own cost and expense,  at any time
prior to the end of the Term for the  applicable  Site if such  removal will not
cause the Site to be in violation of any applicable Law. Any such Alteration may
also be  removed  at the  expiration  of the Term so long as the  Site  restored
substantially  to its  condition  (normal wear and tear  excepted)  prior to the
making of such Alteration;  provided,  however,  that any Severable  Alterations
that  are not  removed  from a Site  within  15-days  after  at the  time of its
surrender by TowerCo  shall become the property of the  Sublessor of the Site as
provided in Section 8(c) hereof.

(b) Whenever  TowerCo is permitted or required to make  Alterations to any Site;
construct,  replace,  maintain or repair the Tower and Improvements of any Site;
maintain  or repair,  or cause  Space  Subtenants  to  maintain  or repair,  any
Communications   Equipment,  or  reconstruct  or  restore,   Subleased  Property
(hereinafter called the "TowerCo Work"), the following provisions shall apply:

     (i)  No TowerCo Work shall be commenced until all  certificates,  licenses,
          permits,  authorizations,  consents and  approvals  necessary  for the
          TowerCo Work, from all governmental  authorities  having  jurisdiction
          with  respect  to any Site or the  TowerCo  Work as set out in Section
          12(c) hereof have been obtained.  SBC shall obtain,  and TowerCo shall
          reimburse  SBC in  accordance  with  Section  17(f)  for  the  cost of
          obtaining,  any FCC or FAA  permits or  approvals  relating to TowerCo
          Work   and   all   other   such   certificates,   licenses,   permits,
          authorizations, consents and approvals shall be obtained by TowerCo at
          TowerCo's cost and expense.

     (ii) TowerCo shall commence and perform the TowerCo Work in accordance with
          standard  operating  procedures  to be  agreed  upon  by  the  parties
          ("Standard Procedures").
<PAGE>   31
                                                                              29

     (iii)TowerCo  shall cause the TowerCo  Work to be done and  completed  with
          industry standard materials and in a good, substantial and workmanlike
          manner, free from faults and defects, and in compliance with all Laws,
          and shall  utilize only  industry  standard  materials  and  supplies.
          TowerCo shall be solely responsible for construction  means,  methods,
          techniques,   sequences  and  procedures,  and  for  coordinating  all
          activities  related to the TowerCo Work, and SBC shall have no duty or
          obligation to inspect the TowerCo Work, but shall have the right to do
          so,  at  reasonable  times,  upon  reasonable  prior  notice  and in a
          reasonable manner.

     (iv) TowerCo shall promptly  commence the TowerCo Work and, once commenced,
          diligently  and  continually  pursue the TowerCo Work and complete the
          TowerCo Work within a reasonable  time.  TowerCo  shall  supervise and
          direct the TowerCo Work utilizing commercially  reasonable efforts and
          reasonable  care,  and shall  assign such  qualified  personnel to the
          TowerCo  Work as may be  necessary  to cause  the  TowerCo  Work to be
          completed in an expeditious fashion.

     (v)  All  TowerCo  Work  shall be  performed  at  TowerCo's  sole  cost and
          expense.  TowerCo  shall  provide  and pay for all  labor,  materials,
          goods, supplies, equipment,  appliances, tools, construction equipment
          and  machinery  and other  facilities  and services  necessary for the
          proper  execution and  completion  of the TowerCo Work.  TowerCo shall
          promptly  pay when due all costs and expenses  incurred in  connection
          with the TowerCo  Work.  TowerCo  shall pay, or cause to be paid,  all
          fees and taxes required by law in connection with the TowerCo Work.

     (vi) TowerCo shall be responsible  for the acts and omissions of all of its
          employees,    contractors,    subcontractors,    engineers,    agents,
          representatives,  advisors and all other persons performing any of the
          TowerCo Work. TowerCo shall be responsible for initiating, maintaining
          and  supervising  all  necessary  safety  precautions  and programs in
          connection  with the  TowerCo  Work,  and  shall  take all  reasonable
          protection to prevent damage, injury or loss to, the TowerCo Work, all
          persons performing TowerCo Work on the Site, all other persons who may
          be involved in or affected by the  TowerCo  Work,  all  materials  and
          equipment  to  be  incorporated   in  the  TowerCo  Work,   Tower  and
          Improvements of such Site.

     (vii)Unless  otherwise  permitted to  self-insure  in accordance  with this
          Sublease, TowerCo shall procure and maintain in full force and effect,
          and shall  cause its  contractors  and  subcontractors  to procure and
          maintain in full force and effect,  with respect to the TowerCo  Work:
          (x) in the case of  TowerCo  only but  subject  to  Section  23,  full
          replacement cost "all-risk",  "builder's risk" insurance, insuring the
          TowerCo  Work;  and (y) the other  types of  insurance  required to be
          maintained  pursuant to Section 23 of this Sublease.  Such  additional
          insurance  policies shall meet the requirements set forth elsewhere in
          this  Sublease  with  respect  to  the  insurance  policies  otherwise
          required to be obtained and maintained by TowerCo under this Sublease.

(c) Before any TowerCo Work is performed or any antennas or other  equipment are
added to a Tower by  TowerCo  or a Space  Subtenant  other  than SBC and the SBC
Affiliates,  TowerCo shall provide SBC with the information described in Exhibit
E ("Procedures For SBC to Process Tower Requests From TowerCo")  attached hereto
<PAGE>   32
                                                                              30

containing  the  following  information  with  respect to any  antennas or other
equipment to be added and the following information, to the extent relevant with
respect  to any  TowerCo  Work to be  performed,  together  with any  additional
information  required  by  Law in  order  for  SBC  to  make  any  necessary  or
appropriate  FAA  or FCC  regulatory  filings  with  respect  thereto:  Proposed
temporary  construction  height (including any temporary  equipment),  Effective
Radiated Power ("ERP") or Equivalent  Isotropically  Radiated Power ("EIRP") (if
microwave);  analysis of Radio Frequency ("RF")  Emissions  pursuant to FCC Rule
1.1307(b); statement of construction method to be used (crane, gin poke, other);
description  of devices  installed  (microwave,  cellular,  other (e.g.  Part 15
device); specification of whether antenna is side mounted or top mounted, and if
top mounted, certification that the antenna tip or other equipment is not taller
than the top of the existing structure).  With respect to any TowerCo Work to be
performed,  TowerCo also shall  provide in such Notice all relevant  information
regarding the nature of such TowerCo Work.  SBC shall  promptly make all FAA and
FCC regulatory  filings as it deems  necessary or appropriate in connection with
such addition of equipment or TowerCo Work.  SBC shall notify  TowerCo  promptly
after the  filing  of any and all such FAA and FCC  regulatory  filings  and the
passage of any  additional  time  required by any  governmental  entity prior to
authorization  to add such  equipment.  After  receipt of such  notice from SBC,
TowerCo or the Space  Subtenant,  as the case may be, may add such  equipment to
the Tower or perform such TowerCo  Work,  provided such addition or TowerCo Work
is consistent  with the  information  set forth in the Notice of TowerCo Work or
Additional Equipment.

(d) During the Term for each Site,  TowerCo  shall have access to the air rights
over SBC's or the applicable SBC Affiliate's  equipment shelters at such Site to
install or construct a stacked equipment shelter or similar structure;  provided
that such stacked shelter or similar  structure shall not have an adverse effect
on, or interfere with,  SBC's or the applicable SBC Affiliate's use of or access
to the Site (including the Reserved Space and SBC's  Improvements at such Site).
TowerCo may submit plans and  specifications  for stacked equipment  shelters or
similar structures designed for use with respect to specific types of SBC or SBC
Affiliate  equipment  shelters.  Provided  SBC shall have  approved a particular
design and the related plans and specifications, TowerCo shall have the right to
install such  structure(s)  at appropriate  Sites to which such design  applies.
TowerCo shall give SBC no less than (3) three business days prior written notice
of the commencement of any such installation.

SECTION 13.       Damage to the Site, Tower or the Improvements.

(a) If there occurs a casualty which damages or destroys of all or a Substantial
Portion of any Site,  then either Party shall have the right to  terminate  this
Sublease as to such Site by written notice to the other Party within thirty (30)
days of the occurrence of such casualty  whereupon the Term shall  automatically
expire as to such Site, on the date of such  casualty,  as if such date were the
Site Expiration Date as to such Site.

(b) If less than a  Substantial  Portion  of any Site  (including  the Tower and
Improvements thereon) is damaged or destroyed by casualty,  TowerCo, at its sole
cost and expense,  shall promptly and diligently  proceed with the adjustment of
TowerCo's  insurance Claims in respect thereof within a period of two (2) months
after the date of the damage and,  thereafter,  if and to the extent required by
this Section 13, promptly commence, and diligently prosecute to completion,  the
Restoration,  repair,  replacement  and rebuilding of the same. The  Restoration
shall  be  carried  on and  completed  in  accordance  with the  provisions  and
conditions of this Section 13.
<PAGE>   33
                                                                              31

(c) All Proceeds of TowerCo's  insurance shall be held by TowerCo for the mutual
benefit of TowerCo and Sublessor on account of such damage,  shall be applied to
the payment of the costs of the  Restoration  and shall be paid out from time to
time as the  Restoration  progresses.  Any portion of the  Proceeds of TowerCo's
insurance applicable to a particular Site remaining after final payment has been
made for work performed on such Site shall be retained by and be the property of
Sublessor.  If the  cost  of  Restoration  exceeds  the  Proceeds  of  TowerCo's
insurance, TowerCo shall pay the excess cost.

(d)  Without  limiting  TowerCo's  obligations  hereunder  in  respect of a Site
subject to a casualty, in the event TowerCo is required to cause the Restoration
of a Site that has suffered a casualty,  TowerCo shall make available to SBC (or
its Affiliate  occupying space on such Site) a portion of the Subleased Property
of such Site for the purpose of such Person locating a temporary  communications
facility,  such as a "cell on wheels",  and shall give such Person priority over
Space Subtenants at such Site as to the use of such portion; provided,  however,
that:  (i) the  placement of such  temporary  communications  facility  does not
interfere in any material respect with TowerCo's  Restoration and repair of such
Improvements or the operations of any Space Subtenant;  (ii) such Person obtains
any permits and approvals,  at such Person's cost,  required for the location of
such  temporary  communications  facility  on such  Site;  and  (iii)  there  is
available space on the Site for placing such temporary communications facility.

(e) The  foregoing  provisions  of this  Section 13 apply only to damage of each
Site by fire,  casualty  or other  cause  occurring  after the  applicable  Site
Commencement Date.

(f) If SBC or its  Affiliate  damages  any  Site as a  result  of  SBC's or such
Affiliate's  negligent or wrongful  act or  omission,  or failure to perform its
obligations under this Sublease, SBC or its Affiliate will, at its sole expense,
promptly  repair  and  restore  the  Subleased  Property  of  such  Site  to its
respective condition prior to such damage.

(g) If TowerCo fails to complete the Restoration of the Subleased  Property,  of
any Site required  under this  Sublease  within two (2) months after the date of
the damage,  SBC may  terminate  this  Sublease as to the  applicable  Site upon
giving TowerCo  written notice of its election to terminate  within fifteen (15)
days following the expiration of such time period,  provided,  however,  that if
TowerCo's failure to complete such Restoration  within such two (2)-month period
is caused by: (i) failure to obtain a new permit, or (ii) TowerCo's inability to
have  access  to the  affected  Site,  such  2-month  period  shall be  extended
accordingly in order to allow TowerCo to complete the Restoration.

(h) This Section 13(h) shall be deemed an express agreement governing any damage
or  destruction  of any Site by fire or other  casualty,  and Section 227 of the
Real Property Law of the State of New York  providing for such a contingency  in
the  absence of an  express  agreement  and any other law of like  import now or
hereafter in force, shall have no application.
<PAGE>   34
                                                                              32

SECTION 14.       Space Subtenants; Interference.

(a) TowerCo acknowledges and agrees that TowerCo will not permit the addition of
any Space  Subtenants  (other than SBC or the SBC  Affiliates  in respect of any
Available Space) at the Subleased Property of any Site to adversely affect SBC's
Reserved Space and its operation, use or enjoyment of any Reserved Space on such
Site,  taking into account customary and commercially  reasonable  practices for
multi-tenant wireless communication sites and towers thereon.

(b) TowerCo shall not and shall not permit any Space Subtenants  (other than SBC
or the SBC  Affiliates in respect of any Available  Space or Reserved  Space) on
the  Subleased  Property of any Site to (i) install or change,  alter or improve
the frequency,  power, or type of the  Communications  Equipment that interferes
with the operation of the Reserved  Space of such Site or is not  authorized by,
or violates,  any applicable Laws or is not made or installed in accordance with
good  engineering  practices (and TowerCo shall require any Space  Subtenant who
subleases  or licenses  Available  Space on any Tower to covenant to comply with
the  foregoing);  or (ii) implement a  configuration  which  interferes with the
operation of SBC's or the SBC Affiliate's  Communications Equipment on such Site
or the Reserved Space thereof.

(c) In the event any Space  Subtenant  installs or operates  any  Communications
Equipment  which is not  authorized  by, or in violation  of, any Laws,  TowerCo
shall  cause  such  Space  Subtenant  to remove  such  Communications  Equipment
promptly, failing which TowerCo shall remove such Communications Equipment.

(d) In the event of any interference occurring as a result of actions of TowerCo
or Space  Subtenants  described  in  Sections  14(b)  above as to the  Subleased
Property  of any  Site,  TowerCo  shall  be  responsible  for  coordinating  and
resolving any such  interference  problems caused by TowerCo or Space Subtenants
(other  than  SBC or any SBC  Affiliate  in  respect  of any  Available  Space),
including,  without limitation,  using its best efforts to correct and eliminate
the interference  within  forty-eight (48) hours of receipt of notification from
SBC and  perform an  interference  study in  accordance  with  industry-standard
procedures.  If the interference  cannot be corrected or eliminated  within such
48-hour period,  TowerCo shall cause, at TowerCo's  option,  any of TowerCo's or
Space  Subtenants'  (other  than  SBC or any SBC  Affiliate  in  respect  of any
Available  Space)  Communications  Equipment  or  Communications  Facility  that
interferes  with the  operation of SBC's or any SBC  Affiliate's  Communications
Facility's  authorized frequency spectrum or signal strength,  to be immediately
powered down or turned off, with the right to turn such interfering equipment or
facility back up or on only during  off-peak hours  specified by SBC in order to
determine whether such interference continues or has been eliminated;  provided,
however, that if any interference  continues at the time the power output of the
interfering  equipment  is  powered  down,  the  Communications  Equipment  that
interferes  with the  operation  of SBC's or any SBC  Affiliate's  Communication
Facility  or  Reserved  Space  shall be  turned  off.  If  TowerCo  or any Space
Subtenant  (other than SBC or its Affiliates in respect of any Available  Space)
cannot  correct or eliminate,  to the  satisfaction  of SBC,  such  interference
within twenty (20) days of receipt of written notice from SBC,  TowerCo shall or
shall cause such Space Subtenant (other than SBC or any SBC Affiliate in respect
of  the  Available   Space)  to  cease  the  operations  of  the   objectionable
Communications  Equipment and to stop  providing  services  from the  applicable
Communication  Facility or the Subleased  Property of the applicable Site in its
entirety until the interference problems are resolved.
<PAGE>   35
                                                                              33

(e) SBC and the SBC  Affiliates  shall not:  (1)  install  or  change,  alter or
improve the  frequency,  power,  or type of the  Communications  Equipment  in a
manner that interferes with the operation of TowerCo's or any Space  Subtenant's
Communications Equipment on a Site or is not authorized by Law or is not made or
installed in accordance  with good  engineering  practices;  or (ii) implement a
configuration  which  interferes  with the  operation  of TowerCo's or any Space
Subtenant's Communications Equipment on such Site.

(f) In the event of any interference  occurring as a result of actions of SBC or
an SBC Affiliate  described in Section 14(e) above as to any Site,  SBC shall be
responsible for coordinating and resolving any such interference problems caused
by SBC or an SBC  Affiliate,  including,  without  limitation,  using  its  best
efforts to correct and eliminate the interference  within forty-eight (48) hours
of receipt of notification from TowerCo. If the interference cannot be corrected
or eliminated  within such 48-hour  period,  SBC shall cause any of SBC's or the
SBC  Affiliate's   Communications  Equipment  or  Communications  Facility  that
interferes   with  the   operation  of   TowerCo's  or  any  Space   Subtenant's
Communications  Facility's  authorized frequency spectrum or signal strength, to
be  immediately  powered  down or  turned  off,  with  the  right  to turn  such
interfering  equipment  or  facility  back up or on only during  off-peak  hours
specified  by TowerCo or the  affected  Space  Subtenant  in order to  determine
whether such interference  continues or has been eliminated;  provided,  that if
any  interference  continues  at the time the power  output  of the  interfering
equipment is powered down, the Communications Equipment that interferes with the
operation  of TowerCo or any Space  Subtenant  Communication  Facility  shall be
turned off. If SBC or the SBC  Affiliate  cannot  correct or  eliminate,  to the
satisfaction  of TowerCo or the  affected  Space  Subtenant,  such  interference
within twenty (20) days of receipt of written  notice from  TowerCo,  SBC or the
SBC Affiliate  shall cease the  operations of the  objectionable  Communications
Equipment  and  stop  providing  services  from  the  applicable  Communications
Facility  or the  Subleased  Property  of the  applicable  Site in its  entirety
(including  the Tower and  Improvements)  until the  interference  problems  are
resolved.

(g)  Notwithstanding  anything in this Section 14 to the contrary,  in the event
any interference occurs in respect of a Site and the source of such interference
is not  readily  determinable,  it  shall be  assumed  that  TowerCo  or a Space
Subtenant  and not SBC or the SBC  Affiliate is the cause of such  interference,
TowerCo  shall be  responsible  for the  performance  of its  obligations  under
Section 14(c) in respect of such interference,  and SBC shall be relieved of any
obligations  under  Section  14(e) in respect of such  interference,  unless and
until  it is  determined  that  SBC or the SBC  Affiliate  is the  cause of such
interference.

SECTION 15.       Taxes and Assessments.

(a)  TowerCo  shall pay all  Taxes and  Assessments  with  respect  to each Site
applicable to all periods  occurring after the Site  Commencement  Date for such
Site on or prior  to the  date on which  such  Taxes  and  Assessments  are due;
provided that TowerCo  shall have the right to contest,  by proper legal actions
or  proceedings  in good faith any Taxes and  Assessments  for which  TowerCo is
responsible  hereunder and, if permitted under  applicable law, to defer payment
<PAGE>   36
                                                                              34

of such Taxes and Assessments pending the outcome of such contest, provided that
at the time of the commencement of any such action or proceeding, and during the
pendency thereof,  (i) no event of default by TowerCo shall have occurred and be
continuing,  (ii) such contest  operates to suspend  collection of the contested
Taxes and  Assessments or claims and is maintained  and prosecuted  continuously
with  diligence,  (iii) the Site would not be subject to  forfeiture  or loss by
reason of the  institution or prosecution of such contest,  (iv) TowerCo,  shall
promptly pay or discharge such Taxes and Assessments and all additional charges,
interest,  penalties and expenses if such contest is terminated or  discontinued
adversely to TowerCo,  and (v) TowerCo shall keep Sublessor  reasonably informed
of any such  contest.  Each  Sublessor  shall  promptly  forward to TowerCo upon
receipt  copies of all bills,  invoices,  statements,  assessments  and  similar
notices  regarding Taxes and Assessments.  TowerCo shall receive any refunds for
Taxes and Assessments paid by TowerCo pursuant to this Sublease. Notwithstanding
the  foregoing,  TowerCo shall not be required to pay any Taxes and  Assessments
payable with respect to a Leased Site if the  applicable  Ground Lease  provides
that the Ground  Lessor is  responsible  therefor  without  pass-through  to the
ground  lessee  and  the  Ground  Lessor   actually  pays  any  such  Taxes  and
Assessments.  If the Ground  Lessor does not pay any such Taxes and  Assessments
and either Party becomes  aware of it, the Parties  will, at TowerCo's  expense,
cooperate and use commercially  reasonable efforts to cause the Ground Lessor to
pay such Taxes and Assessments.

(b) In the years that include the Site  Commencement Date or the Site Expiration
Date of this  Sublease  as to any Site,  any Taxes and  Assessments  (determined
without  regard  to the  Term)  for  which  TowerCo  is  responsible  to any SBC
Affiliate  under  this  section  of this  Sublease  and that are  calculated  or
assessed on the basis of a time period (e.g.,  property Taxes assessed annually)
shall be  prorated  proportionately  by the  number of days in each such  period
during the time period of assessment that includes the Site Commencement Date or
Site  Expiration  Date,  as the case may be.  TowerCo's  obligations  under this
Section 15 to SBC Affiliates  shall be limited to that  proportionate  amount of
such Taxes and Assessments attributable to the period during which this Sublease
is in effect with respect to such Site.

(c) The Parties  acknowledge  that Taxes and Assessments  required to be paid by
TowerCo  hereunder  ("TowerCo  Taxes") and Taxes and  Assessments  ("Non-TowerCo
Taxes")  which are not  TowerCo's  responsibility  hereunder  (such as  personal
property  taxes  with  respect  to SBC's or any SBC  Affiliates'  Communications
Equipment or personal  property taxes with respect to properties not included in
the Subleased  Property) may not be assessed  separately  (any TowerCo Taxes and
Non-TowerCo Taxes which are not separately assessed, "Commonly-Assessed Taxes").
The parties agree as follows with respect to  Commonly-Assessed  Taxes:  (i) SBC
shall  prepare  all  returns  with  respect  to  Commonly-Assessed  Taxes in the
ordinary  course and with the same degree of diligence  that it  exercises  with
respect to similar tax  compliance  matters;  (ii) upon the  preparation of such
returns,  SBC shall submit each such return  (together  with all  relevant  work
papers) to TowerCo for its approval  (which  approval shall not be  unreasonably
withheld and shall be limited to matters which bear on the TowerCo Taxes); (iii)
TowerCo  shall  respond to SBC's  submission  not later than  fifteen  (15) days
following the date on which SBC submits each such return for TowerCo's  approval
(with  failure to respond  being deemed  approval of such  return);  (iv) in the
event that any  adjustment of a return is necessary,  SBC shall take  reasonable
steps to make such  adjustment(s)  (which shall be subject to the same  approval
<PAGE>   37
                                                                              35

process provided in clauses (ii) and (iii) above)  including,  if necessary,  by
filing an amended  return;  and (v)  TowerCo's  share of such  Commonly-Assessed
Taxes  shall be  determined  based on the  underlying  facts and  circumstances,
taking into account the basis for accessing such Commonly-Assessed  Taxes in the
relevant  jurisdiction at the time,  subject to the agreement of SBC and TowerCo
each of which shall seek such agreement in good faith.  TowerCo shall  reimburse
SBC or the applicable Sublessor for TowerCo's share of  Commonly-Assessed  Taxes
within 30 days after request, which request shall be accompanied by the relevant
portions of the  applicable  tax return and all  relevant  work  papers.  If the
Parties cannot agree on the allocation of any Commonly-Assessed  Taxes or on the
manner of paying or reporting the same,  the Parties shall submit the dispute to
an independent  accounting firm acceptable to the Parties, and the resolution of
such firm (which resolution shall be consistent with the foregoing provisions of
this Section 15(c)) shall be binding on the Parties.  TowerCo and SBC shall each
bear 50% of the cost of such determination. TowerCo and SBC shall cooperate with
each  other,  and  make  available  to each  other  such  information  as  shall
reasonably be necessary,  in connection  with the preparation of tax returns for
Commonly-Assessed  Taxes and any audit or judicial or administrative  proceeding
relating  to  the  same.  The  Parties  shall  retain  information  relating  to
Commonly-Assessed  Taxes for a period of four years  following  the close of the
taxable year to which information relates, provided that in the case of an audit
or proceeding relating to Commonly-Assessed Taxes the relevant information shall
be retained until there is a final adjudication of the same.

SECTION 16.       Utilities.

         TowerCo shall make all  arrangements  for, and thereafter shall pay, or
cause to be paid,  when due all  charges for  connection  of all  utilities  and
services  to such  Site  for the use of  Space  Subtenants,  including,  but not
limited to, electricity, telephone, power, and other utility used or consumed by
Space  Subtenants of such Site. As among SBC (together with the SBC  Affiliates)
and  all new  Space  Subtenants,  TowerCo  shall  cause  utility  charges  to be
separately  metered,  and SBC or the SBC Affiliate (as the case may be) shall be
separately responsible for its own utility charges.

SECTION 17.       Governmental Permits.

(a) In addition to and not in limitation  of the  provisions of Section 11(a) of
this  Sublease,  TowerCo  shall,  at its own cost and  expense,  provide SBC all
necessary  and  appropriate  information  requested by SBC for SBC to obtain and
maintain  in effect all  certificates,  permits,  licenses  and other  approvals
relating  to FAA or FCC  regulations  and  TowerCo  shall,  at its own  cost and
expense, obtain and maintain in effect all certificates,  permits,  licenses and
other  approvals  (other  than those  relating to FCC and FAA  regulations)  and
comply with all Laws,  required or imposed by  governmental  authorities  (other
than those relating to FCC or FAA regulations), in connection with the operation
and  maintenance  of the Subleased  Property of each Site  (including  Tower and
Improvements  thereon).  As part of TowerCo's obligation to provide information,
TowerCo  shall  provide  SBC  access  to  data,  including  resistance  changes,
necessary  to  monitor  the  lighting  systems  at each  Site to the  extent  in
TowerCo's possession.

(b) TowerCo shall  cooperate with SBC in SBC's efforts to obtain and maintain in
effect any  certificates,  permits,  licenses and other  approvals and to comply
with any Laws required or imposed on SBC or the SBC  Affiliates by  governmental
authorities, applicable to the Reserved Space of each Site.
<PAGE>   38
                                                                              36

(c) SBC shall,  at its own cost and  expense,  obtain and maintain in effect all
certificates,  permits,  licenses and other  approvals and comply with all Laws,
required or imposed by  governmental  authorities,  in connection with operation
and  maintenance  of  the  Reserved  Space  of  each  Site,  including,  without
limitation, FCC regulations.  With the cooperation of TowerCo set out in Section
17(a) hereof, SBC, at TowerCo's cost and expense, also shall obtain and maintain
in effect all certificates,  permits,  licenses, and other approvals required or
imposed by  governmental  authorities in connection  with FAA or FCC regulations
relating to the operation and maintenance of the Subleased Property of each Site
(including  the Towers and  Improvements  thereon).  The cost of  obtaining  and
maintaining  such FCC or FAA permits or approvals  shall be reimbursed to SBC in
accordance with Section 17(f).

(d) SBC shall  cooperate with TowerCo in TowerCo's  efforts to provide  required
information  and to comply  with all Laws  required  or imposed by  governmental
authorities, applicable to each Site.

(e)  SBC  shall  be  afforded  access  to  all  of  TowerCo's  records,   books,
correspondence,  instructions,  blueprints, permit files, memorandum and similar
data relating to the compliance of the Towers with all applicable Laws or if SBC
otherwise  provides  reasonable  justification   therefore,   except  privileged
documents or where  disclosure is prohibited by law.  TowerCo shall also provide
SBC with an  electronic  interface or other real time access to TowerCo's  Tower
administration  database  which  shall  enable  access to  detailed  information
concerning  collocations.  Such  information  shall be open for  inspection  and
copying  upon  reasonable  notice  by  SBC,  at its  cost,  and  its  authorized
representatives  at reasonable hours at TowerCo's  principal office and shall be
retained by TowerCo for period of three (3) years after the  expiration  of this
Sublease.

(f) The cost of SBC's  obtaining  and  maintaining  all FCC and FAA  permits and
approvals  relating to the operation  and  maintenance  of the  Subleased  Space
(excluding  the  Reserved  Space) and TowerCo  Work shall be borne by TowerCo in
accordance with Sections 12(b)(i) and 17(c) (the "Reimbursable  Costs"). SBC and
TowerCo have agreed on the Reimbursable Costs pursuant to a separate  agreement.
SBC shall provide  TowerCo with an invoice for  Reimbursable  Costs on a monthly
basis,  which  amount  shall be paid by TowerCo to SBC within ten (10)  business
days of TowerCo's receipt of such invoice.  If the  organizational  structure of
SBC's  FCC and FAA  compliance  department  materially  changes  or the  cost of
obtaining and maintaining FCC and FAA permits  materially  changes,  the parties
agree to use good faith efforts to negotiate  modifications  to the Reimbursable
Costs  agreement  described  above and the  respective  responsibilities  of the
parties with respect to FAA and FCC compliance work.

SECTION 18.       No Liens.

(a) TowerCo  shall not create or permit any Lien (other  than  Permitted  Liens)
against any Site, or any part thereof.  If any Lien (other than Permitted Liens)
is filed against all or any part of any Site, TowerCo shall cause the same to be
<PAGE>   39
                                                                              37

discharged by payment,  satisfaction  or posting of bond within thirty (30) days
after TowerCo has obtained knowledge of such Lien. If TowerCo fails to cause any
Lien (other than Permitted  Liens) to be discharged  within the permitted  time,
SBC may cause it to be  discharged  and may pay the amount of such Lien in order
to do so.  If SBC  makes  any such  payment,  all  amounts  paid by SBC shall be
payable by TowerCo to SBC upon demand. "Permitted Liens" means, as to each Site:
(i) Permitted  Subleasehold Mortgages of TowerCo's subleasehold interest in such
Site  and  Permitted  Subleasehold  Pledges;  (ii)  Space  Subtenants'  sublease
interests in the Subleased Space of such Site;  (iii) Liens existing on the Site
Commencement  Date for such Site;  (iv) Liens arising by,  through or under SBC,
its Affiliates or any other occupant of the Reserved Space;  (v) Liens for taxes
not yet due and payable or which are being contested in good faith in accordance
with the  provisions  of Section 15; (vi) Liens  created by the  underlying  fee
owners  of  the  Leased  Sites;  (vii)  easements,  rights  of way  and  similar
encumbrances  provided  that such  encumbrances  do not have a material  adverse
effect  on the use or  enjoyment  of such  Site or the  Reserved  Space  and are
approved by SBC, such approval not to be unreasonably  withheld or delayed;  and
(viii)  mechanics'  liens for  amounts  which are not more than thirty (30) days
overdue.

(b) TowerCo may, at TowerCo's sole cost and expense,  in its own name and on its
own  behalf  or in the name of and on behalf of the  Sublessor,  in good  faith,
contest any claim of Lien and, in the event of any such contest, may permit such
claim of Lien so contested to remain unpaid, unsatisfied and undischarged during
the period of such contest and any appeal therefrom; provided, however, that, if
any Site, the Subleased  Property of any Site or any part thereof are subject to
imminent danger of loss or forfeiture by virtue of or by reason of such claim of
Lien,  such claim of Lien shall be  complied  with  forthwith  or TowerCo  shall
deposit with the Sublessor a sum of money  reasonably  required by the Sublessor
as security to protect the Subleased Property of such Site from any such loss or
forfeiture.  The  Sublessor,  at the sole cost and  expense  of  TowerCo,  shall
cooperate fully with TowerCo in any such contest.

(c) Any Permitted  Subleasehold Mortgage or Permitted  Subleasehold Pledge shall
be subject to each and every term, covenant, condition, agreement,  requirement,
restriction  and provision set forth in this Sublease and subject to all rights,
title and interest of SBC and each SBC Affiliate.

(d)  Within  ten (10) days  after the  granting  of any  Permitted  Subleasehold
Mortgage or Permitted  Subleasehold Pledge, TowerCo shall deliver to SBC a true,
correct and fully  executed  copy of all  documents  pertaining  thereto and the
indebtedness  secured  thereby.  Promptly  upon  TowerCo's  receipt of copies of
recorded documents  evidencing the recordation thereof and bearing the recording
information  therefor,  TowerCo  shall  deliver  to SBC a copy of such  recorded
documents.

(e) The  Sublessor  shall  execute  any  necessary  easement or right of way for
utilities for any Site promptly following any request by TowerCo,  provided such
easement  or  right  of way does  not  have an  adverse  effect  on SBC's or its
Affiliate's  use or  enjoyment  of the  Reserved  Space  of such  Site or on the
ownership  by the  Sublessor  of the  Tower  on  such  Site,  including  without
limitation the operation of SBC's Communications Equipment thereon.

(f) Other than as  provided  in  Section  21, SBC shall not create or permit any
Lien against the Subleased  Property of any Site,  or any part  thereof.  If any
Lien is filed against all or any part of the Subleased Property of any Site, SBC
<PAGE>   40
                                                                              38

shall cause the same to be  discharged  by payment,  satisfaction  or posting of
bond within thirty (30) days after demand  therefor by TowerCo.  If SBC fails to
cause any Lien to be discharged within the permitted time,  TowerCo may cause it
to be  discharged  and may pay the  amount  of such  Lien in order to do so.  If
TowerCo makes any such payment,  all amounts paid by TowerCo shall be payable by
SBC to TowerCo upon demand.  Nothing in this Sublease  shall  prohibit SBC or an
SBC Affiliate from permitting a Lien against its interest under the Ground Lease
or Reserved  Space of any Site subject to (i) the  restrictions  on Transfer set
forth in Section 25 and (ii) SBC's and the Sublessor's  obligations  pursuant to
Section 35(e) hereof in the event TowerCo  exercises its right to acquire all or
portion of the Sites.  Notwithstanding  the  foregoing,  any Lien against  SBC's
interest  under the Ground  Lease shall only be permitted if such Lien is either
subject to and  subordinate to this Sublease and the purchase  option  contained
herein or such  lienholder  executes  an NDA  substantially  similar  to the NDA
provided for in Section 21.

(g) SBC may,  at SBC's  sole  cost and  expense,  in its own name and on its own
behalf or in the name of and on behalf of TowerCo,  in good  faith,  contest any
claim of Lien and,  in the event of any such  contest,  may permit such claim of
Lien so contested to remain  unpaid,  unsatisfied  and  undischarged  during the
period of such contest and any appeal therefrom; provided, however, that, if the
Subleased  Property  of any Site or any part  thereof  are  subject to  imminent
danger of loss or  forfeiture  by virtue of or by reason of such  claim of Lien,
such claim of Lien shall be complied  with  forthwith or SBC shall  deposit with
TowerCo a sum of money  reasonably  required  by TowerCo as  security to protect
TowerCo's  interest in the Subleased Property of such Site from any such loss or
forfeiture.  TowerCo, at the sole cost and expense of SBC, shall cooperate fully
with SBC in any such contest.

(h) SBC  hereby  waives  any lien  rights  it may  have  concerning  each  Space
Subtenant's Improvements and Communications Equipment.

SECTION 19.       Condemnation.

(a) If there occurs a Taking of all or a Substantial  Portion of any Site, other
than a Taking for  temporary  use,  then  either  Party  shall have the right to
terminate  this  Sublease  as to such Site by written  notice to the other Party
within  thirty (30) days of the  occurrence  of such Taking  whereupon  the Term
shall  automatically  expire as to such Site, on the Date of Taking,  as if such
date were the Site Expiration Date as to such Site.

(b) If there  occurs a Taking of less than a  Substantial  Portion  of any Site,
then this Sublease and all duties and obligations of TowerCo under this Sublease
in respect of such Site shall remain  unmodified,  unaffected  and in full force
and effect.  TowerCo shall promptly  proceed to reconstruct,  restore and repair
the  remaining  portion of the  Subleased  Property  of such Site (to the extent
feasible) to a condition substantially equivalent to the condition thereof prior
to the Taking.  TowerCo shall be entitled to apply the Award received by TowerCo
to the  reconstruction,  Restoration and repair of any Subleased Property of any
Site from time to time as such work  progresses.  If the cost of the repair work
exceeds the Award  recovered by TowerCo,  TowerCo  shall pay the excess cost. If
the Award  exceeds the cost of the repair work,  the excess shall be paid to the
Sublessor.
<PAGE>   41
                                                                              39

(c) If there  occurs  a  Taking  of any  Subleased  Property  of any Site or any
portion  thereof,  for temporary  use,  then this Sublease  shall remain in full
force and effect as to such Site for the  remainder  of the then  current  term;
provided,  however,  that during such time as TowerCo shall be out of possession
of such  Subleased  Property  by reason of such  Taking,  the  failure  to keep,
observe,  perform,  satisfy and comply with those terms and  conditions  of this
Sublease  compliance with which are  effectively  impractical or impossible as a
result of TowerCo's being out of possession of such Subleased Property shall not
be an event of  default  hereunder.  The  Award  for any such  temporary  Taking
payable  for any  period  prior to the  Site  Expiration  Date  shall be paid to
TowerCo and, for any period thereafter, to the Sublessor.

SECTION 20.       Waiver of Subrogation; Indemnity.

(a) Except as provided in this Sublease,  to the extent  permitted by applicable
Laws, TowerCo and SBC hereby waive any and all rights of recovery, claim, action
or cause of action against each other,  their  respective  agents,  officers and
employees,  for any loss or damage that may occur to the  Subleased  Property of
each Site, by reason of fire, the elements,  or any other cause insured against,
or required  to be insured  against,  under the terms of  policies of  insurance
maintained,  or required to be  maintained,  for the Subleased  Property of such
Site,  by TowerCo or SBC (as the case may be) under the terms of this  Sublease,
regardless of cause or origin.

(b)  Subject  to the  provisions  of  Section  20(a)  above,  TowerCo  agrees to
indemnify and to hold each SBC Indemnitee harmless from any and all Claims, with
respect  to bodily  injury,  personal  injury or  property  damage  suffered  or
incurred  by such SBC  Indemnitee  by reason  of, or  arising  out of  TowerCo's
sublease or lease,  as the case may be,  operation and  maintenance of each Site
(including the Tower and Improvements thereon),  including,  without limitation:
(i) any  default,  breach,  performance  or  nonperformance  by  TowerCo  of its
respective  obligations  and covenants under this Sublease,  including,  without
limitation,  Sections  12, 14 and 17,  hereof;  (ii) any Claims  against any SBC
Indemnitee  arising  out of or  resulting  from (x)  TowerCo's  use,  operation,
maintenance or occupancy of any part of the Site or resulting from the condition
of the  Site  or (y)  any  Space  Subtenant's  use,  operation,  maintenance  or
occupancy of its Communications Facility; (iii) any failure of TowerCo to comply
with any  applicable  Laws or with the directives of FCC and FAA that TowerCo is
required to comply with pursuant to this Sublease or under applicable Laws; (iv)
any Claims arising out of or resulting  from TowerCo's or any Space  Subtenant's
acts or omissions or the negligence or  intentional  acts or omissions of any of
their respective  agents,  employees,  engineers,  contractors,  subcontractors,
licensees,  or invitees in or about the Subleased Property of each Site, and (v)
any other provision of this Sublease which provides that TowerCo shall indemnify
and hold harmless any SBC Indemnitee in respect of the matters contained in such
provision.  If any action or proceeding is brought against any SBC Indemnitee by
reason of any such Claim, TowerCo upon notice from such SBC Indemnitee covenants
and agrees to defend such action or proceeding at its expense.

(c) Subject to the  provisions of Section  20(a) above,  SBC agrees to indemnify
and to hold  each  TowerCo  Indemnitee  harmless  from any and all  Claims  with
respect  to bodily  injury,  personal  injury or  property  damage  suffered  or
incurred  by TowerCo by reason of, or arising  out of (i) any  default,  breach,
performance or  nonperformance  of SBC's  obligations  and covenants  under this
Sublease  (including,  without  limitation,  SBC's covenants under Section 17(c)
hereof);  (ii) any Claims against TowerCo arising out of or resulting from SBC's
<PAGE>   42
                                                                              40

use, operation,  maintenance or occupancy of SBC's  Communications  Equipment or
the Reserved Space, to the extent TowerCo is not responsible  therefor under the
terms of this Sublease,  (iii) SBC's failure to comply with any applicable  Laws
or with the directives of FCC and FAA as to SBC's Communications Equipment; (iv)
any  Claims  against  TowerCo  arising  out of or  resulting  from  any  acts or
omissions or the negligence or intentional  actions or omissions of any of SBC's
agents,  employees,  engineers,   contractors,   subcontractors,   licensees  or
invitees;  and (v) any other  provision of this Sublease which provides that SBC
shall indemnify and hold harmless TowerCo or any Affiliate thereof in respect of
the matters contained in such provision.  If any action or proceeding is brought
against  TowerCo  by reason of any such  Claim,  SBC upon  notice  from  TowerCo
covenants and agrees to defend such action or proceeding at its expense.

SECTION 21.       Subordination and Attornment.

(a) This Sublease and all rights of TowerCo therein,  and all interest or estate
of TowerCo in the Subleased Property of each Site, or any portion thereof, shall
be subordinate to any and all Mortgages,  which at any time during the Term, may
be placed upon the Subleased Property, or any portion thereof, by SBC or any SBC
Affiliate,  and  to  any  replacements,  renewals,  amendments,   modifications,
extensions or refinancing  thereof, and to each and every advance made under any
Mortgage;  provided,  however,  that the subordination and attornment  contained
herein  shall not be  effective  unless the  existing  or any  future  Mortgagee
thereunder  shall  execute  and  deliver  an NDA in  favor of  TowerCo,  in form
reasonable  satisfactory  to TowerCo and its lenders  providing  that:  (i) such
Mortgagee  will  at all  times  fully  recognize  TowerCo's  rights  under  this
Sublease,  including the purchase option contained herein, and in the event of a
foreclosure  under any such Mortgage shall not disturb  TowerCo's  possession of
the Subleased  Property and will recognize such purchase  option,  so long as no
event of default shall have occurred and be subsisting hereunder, and so long as
TowerCo shall attorn to the purchaser upon such foreclosure;  and (ii) that upon
Mortgagee  acquiring  title to the  Subleased  Property,  TowerCo  shall  attorn
directly  to such  Mortgagee.  TowerCo  shall  agree  to such  other  terms  and
conditions in the NDA as may be reasonably required by such Mortgagee,  provided
that such terms and conditions do not affect TowerCo's  rights,  nor increase or
alter any of TowerCo's obligations, under this Sublease.

(b) Subject to the provision of Section 21(a), TowerCo shall execute in a timely
manner instruments that may be required to evidence this  subordination  clause,
in respect of the Subleased Property of each Site.

(c) The applicable  Sublessor shall enter into a subordination,  non-disturbance
and  attornment  agreement with any Space  Subtenants at such Space  Subtenant's
request.  Such  agreement  shall  be in  form  reasonably  satisfactory  to  the
applicable Sublessor and the applicable Space Subtenant and shall provide, among
other  things,  that  Sublessor  shall  not  terminate  such  Space  Subtenant's
subleasehold  interest in the  applicable  Site by reason of  TowerCo's  default
hereunder or the early  termination of this Sublease due to a default by TowerCo
or  otherwise,  so  long  as  the  Space  Subtenant  is not  in  default  in the
performance of the terms,  provisions and conditions contained in the applicable
sublease beyond notice and grace.
<PAGE>   43
                                                                              41

SECTION 22.       Environmental Covenants.

(a) For purposes of this Sublease,  the following terms shall have the following
meanings:  (i) "Hazardous Material" or "Hazardous  Materials" means and includes
petroleum products, flammable explosives, radioactive materials, asbestos or any
material containing asbestos, polychlorinated biphenyls, or any hazardous, toxic
or  dangerous  waste,  substance  or  material  defined  as such or defined as a
hazardous  substance  or any  similar  term,  by, in or for the  purposes of the
Environmental  Laws,  including,  without  limitation  Section 101(14) of CERCLA
(hereinafter  defined);  provided  that the  term  "Hazardous  Materials"  shall
exclude quantities of materials or substances maintained by SBC, its Affiliates,
TowerCo  and  Space  Subtenants  on or  about  any  Site  (including  Tower  and
Improvements  thereon)  in the  ordinary  course  of  business,  so long as such
materials are maintained in accordance with the applicable  Environmental  Laws:
(ii)  "Release"  shall have the meaning given such term, or any similar term, in
the Environmental Laws, including, without limitation Section 101(22) of CERCLA;
and (iii)  "Environmental  Law" or  "Environmental  Laws"  shall mean any "Super
Fund" or "Super Lien" law, or any other federal,  state or local  statute,  law,
ordinance, code, rule, regulation,  order or decree, regulating,  relating to or
imposing liability or standards of conduct concerning any Hazardous Materials as
may now or at any time hereafter be in effect,  including,  without  limitation,
the  following,  as same may be amended or replaced  from time to time,  and all
regulations  promulgated  thereunder or in connection  therewith:  the Superfund
Amendments  and  Reauthorization   Act  of  1986  ("SARA");   The  Comprehensive
Environmental Response,  Compensation and Liability Act of 1980 ("CERCLA");  The
Clean Air Act ("CAA"); the Clean Water Act ("CWA"); The Toxic Substances Control
Act ("TSCA");  The Solid Waste Disposal Act ("SWDA"), as amended by the Resource
Conversation and Recovery Act ("RCRA");  the Hazardous Materials  Transportation
Act: and the Occupational Safety and Health Act of 1970 ("OSHA").

(b) As to each Site, SBC represents and warrants to TowerCo that, as of the Site
Commencement Date for such Site, (i) to the best of SBC's knowledge,  no portion
of the  Land of such  Site is used for the  storage,  processing,  treatment  or
disposal of Hazardous Materials, except as set forth in any environmental report
heretofore delivered to TowerCo;  (ii) to the best of SBC's knowledge except for
such  deminimus  quantities  that would not trigger a reporting  or  remediation
obligation under any applicable  Environmental Law, no Hazardous  Materials have
been  released,  introduced,  spilled,  discharged or disposed of, nor has there
been a threat of  release,  introduction,  spill,  discharge  or  disposal  of a
Hazardous Materials, on, in, or under the Land of such Site, except as set forth
in any environmental report heretofore  delivered to TowerCo;  (iii) to the best
of SBC's  knowledge,  there are no pending Claims,  administrative  proceedings,
judgments,  declarations,  or orders, whether actual or threatened,  relating to
the presence of Hazardous  Materials on, in or under the Land of such Site; (iv)
to the best of SBC's knowledge,  the Land of such Site is in compliance with all
applicable Environmental Laws; and (v) to the best of SBC's knowledge, there are
no pending or threatened or contemplated  condemnation  actions involving all or
any portion of the Land of such Site. For purposes of this Section, "to the best
knowledge  of," or words of similar  import with  reference  to SBC means actual
knowledge of the management of SBC and such actual  knowledge will be imputed to
the  management of SBC if the Hazardous  Materials were brought to the Site by a
SBC Group Member.
<PAGE>   44
                                                                              42

(c) Except for any matters for which SBC assumes responsibility pursuant to this
Sublease,  TowerCo  covenants and agrees that:  (i) TowerCo shall not conduct or
allow to be conducted upon any Site any business  operations or  activities,  or
employ or use a Site, to generate, manufacture, refine, transport, treat, store,
handle, dispose of, transfer, produce, or process Hazardous Materials;  provided
that  TowerCo  shall  have the right to bring,  use and keep and allow any Space
Subtenant to bring and keep on the Subleased Property of each Site in compliance
with all applicable  Laws,  batteries,  generators and associated fuel tanks and
other substances  commonly used in the industry  necessary for the operation and
maintenance  of  each  Site;  (ii)  TowerCo  shall  carry  on its  business  and
operations at each Site in compliance in all respects  with,  and will remain in
compliance with, all applicable  Environmental  Laws and shall require all Space
Subtenants  to do the  same:  (iii)  TowerCo  shall  not  create or permit to be
created  any Lien  against  any Site for the costs of any  response,  removal or
remedial action or clean-up of Hazardous Materials;  (iv) TowerCo shall promptly
conduct and complete all investigations,  studies, sampling and testing, and all
remedial,  removal,  and other  actions  necessary  to clean up and  remove  all
Hazardous  Materials  on, from or  affecting  each Site in  accordance  with all
applicable  Environmental Laws; (v) TowerCo shall promptly notify SBC in writing
if TowerCo receives any notice,  letter,  citation,  order, warning,  complaint,
claim or demand that:  (w) TowerCo or any Space  Subtenant has  violated,  or is
about to violate,  any Environmental  Law, (x) there has been a Release or there
is a threat of Release,  of Hazardous  Materials at or from the applicable Site,
(y) TowerCo or any Space Subtenant may be or is liable, in whole or in part, for
the costs of cleaning up,  remediating,  removing or  responding to a Release of
Hazardous  Materials,  or  (z) a  Site  are  subject  to a  Lien  favor  of  any
governmental  entity for any liability,  cost or damages under any Environmental
Law.

(d) SBC covenants and agrees that as to each Site:  (i) SBC shall not conduct or
allow  to be  conducted  upon  any  Reserved  Space  of any  Site  any  business
operations  or  activities,  or employ or use a Reserved  Space of any Site,  to
generate,  manufacture,  refine,  transport,  treat, store, handle,  dispose of,
transfer, produce, or process Hazardous Materials;  provided that SBC shall have
the right to bring, use and keep on the Reserved Space of any Site in compliance
with all applicable  Laws,  batteries,  generators and associated fuel tanks and
other substances  commonly used in the industry  necessary for the operation and
maintenance  of each  Reserved  Space of any Site;  (ii) SBC shall  carry on its
business and  operations on the Reserved  Space of any Site in compliance in all
respects with, and will remain in compliance with, all applicable  Environmental
Laws;  (iii) SBC shall not create or permit to be created  any Lien  against any
Reserved  Space of any Site for the costs of any  response,  removal or remedial
action or clean-up of Hazardous  Materials;  (iv) SBC shall promptly conduct and
complete all investigations,  studies,  sampling and testing,  and all remedial,
removal,  and other  actions  necessary  to clean up and  remove  all  Hazardous
Materials  on, from or affecting  the Reserved  Space of each Site in accordance
with all applicable Environmental Laws; (v) SBC shall promptly notify TowerCo in
writing if SBC receives any notice, letter, citation, order, warning, complaint,
claim  or  demand  that:  (w) SBC has  violated,  or is about  to  violate,  any
Environmental Law, (x) there has been a Release or there is a threat of Release,
of Hazardous Materials at or from the Reserved Space of any Site, (y) SBC may be
or is liable,  in whole or in part,  for the costs of cleaning up,  remediating,
removing or responding to a Release of Hazardous Materials,  or (z) the Reserved
Space of any Site is subject to a Lien in favor of any  governmental  entity for
any  liability,  cost or  damages  under  any  Environmental  Law.  SBC  further
covenants and agrees that the covenants  contained in this Section 22(d) and the
<PAGE>   45
                                                                              43

indemnifications  provided for in Section 22(f) shall also apply with respect to
(i) any  operations or  activities  of SBC conducted  upon space at a Site other
than the Reserved  Space,  and (ii) any operations of any SBC Affiliate upon any
Reserved Space or any space at a Site other than the Reserved Space.

(e) Unless  resulting  or arising  solely from the  negligent or willful acts or
omissions of SBC or SBC's Affiliates, employees, agents, engineers, contractors,
subcontractors,  licensees or  invitees,  or from any other acts or omissions of
such parties in violation of this Sublease, TowerCo agrees to indemnify and hold
SBC and SBC Indemnitees harmless from and against any and all Claims,  including
Claims of any and every kind whatsoever paid, incurred, suffered by, or asserted
against SBC or SBC  Affiliates  or the Site for, with respect to, or as a result
of the  following:  (i) the  presence  in,  on,  over or under,  or the  escape,
seepage, leakage, spillage,  discharge,  emission or Release on or from the Site
of any Hazardous  Materials  prior to the  applicable  Site  Expiration  Date or
earlier  date of  termination  of  this  Sublease;  (ii)  the  violation  of any
Environmental  Laws  relating to or affecting  the Site prior to the  applicable
Site  Expiration  Date or earlier date of termination of this Sublease;  (iii) a
Release of any Hazardous  Materials or the violation of any of the Environmental
Laws prior to the applicable Site Expiration Date or earlier date of termination
of this Sublease in connection with any other property  owned,  operated or used
by or on behalf of TowerCo, which violation or Release gives or may give rise to
any rights  whatsoever in any Party with respect to the Site by virtue of any of
the Environmental  Laws; (iv) any warranty or representation  made by TowerCo in
this Section 22 is or becomes  false or untrue in any material  respect;  or (v)
the  violation  or breach of, or the failure of TowerCo to fully and  completely
keep, observe, satisfy, perform and comply with, any agreement,  term, covenant,
condition, requirement, provision or restriction of this Section 22.

(f) Unless  resulting or arising from the negligent or willful acts or omissions
of   TowerCo   or   TowerCo's   employees,   agents,   engineers,   contractors,
subcontractors,  licensees or  invitees,  or from any other acts or omissions of
such  parties in violation of this  Sublease,  SBC agrees to indemnify  and hold
TowerCo and TowerCo  Indemnitees  harmless  from and against any and all Claims,
including Claims of any and every kind whatsoever paid,  incurred,  suffered by,
or asserted  against TowerCo or the Reserved Space of any Site for, with respect
to, or as a result of the following:  (i) the presence in, on, over or under, or
the escape, seepage,  leakage,  spillage,  discharge,  emission or Release on or
from the  Reserved  Space of any Site of any  Hazardous  Materials  prior to the
applicable Site Expiration Date or earlier date of termination of this Sublease;
(ii) the  violation  of any  Environmental  Laws  relating to or  affecting  the
Reserved  Space of any Site  prior to the  applicable  Site  Expiration  Date or
earlier date of termination  of this Sublease;  (iii) a Release of any Hazardous
Materials  or  the  violation  of any of the  Environmental  Laws  prior  to the
applicable  Site Expiration Date or earlier date of termination of this Sublease
in connection with any other property owned, operated or used by or on behalf of
SBC, which violation or Release gives or may give rise to any rights  whatsoever
in any Party with respect to the Reserved  Space of any Site by virtue of any of
the Environmental  Laws; (iv) any warranty or representation made by SBC in this
Section 22 is or becomes  false or untrue in any  material  respect;  or (v) the
violation or breach of, or the failure of SBC or any SBC  Affiliate to fully and
completely keep, observe, satisfy, perform and comply with, any agreement, term,
covenant, condition, requirement, provision or restriction of this Section 22.
<PAGE>   46
                                                                              44

(g) Notwithstanding  anything to the contrary in this Sublease, in the event any
Claim of a type giving rise to  indemnification  obligations under Section 22 is
asserted against a TowerCo  Indemnitee and it cannot be readily  determined that
it was the act or omission of SBC or its Affiliate that gave rise to such Claim,
it shall be assumed for all  purposes  hereof that it was  TowerCo's  or a Space
Subtenant's act or omission,  TowerCo shall indemnify SBC Indemnitees in respect
of such Claim  pursuant to Section  22(e),  and SBC shall have no  obligation or
liability to any TowerCo Indemnitee in respect of such Claim unless and until it
is finally determined that SBC's or its Affiliate's act or omission gave rise to
such Claim.  The provisions of this Section 22 shall survive the applicable Site
Expiration  Date  or  earlier  termination  of  this  Sublease.   The  foregoing
provisions of this Section 22 are not intended to limit the generality of any of
the other provisions of this Sublease.

SECTION 23.       Insurance.

(a) SBC shall procure,  and shall maintain in full force and effect at all times
during the Term as to the Sites,  the following  types of insurance with respect
to the Reserved  Space of the Sites,  and, if  applicable,  any of the Available
Space  subleased to SBC or its Affiliates  pursuant to Section 24(d),  paying as
the same become due all premiums therefor:

(i)      commercial  general public  liability  insurance  insuring  against all
         liability  of  SBC,  its  Affiliates  and  their  respective  officers,
         employees,  agents, licensees and invitees arising out of, by reason of
         or in connection with the use or occupancy of the Reserved Space of the
         Sites and, if applicable,  any of the Available  Space subleased to SBC
         or its Affiliates  pursuant to Section  24(d),  if any, in an amount of
         not less than  $1,000,000  for bodily  injury or  property  damage as a
         result of one  occurrence,  and not less  than  $2,000,000  for  bodily
         injury or property damage in the aggregate;

(ii)     umbrella or excess  liability  insurance with limits not less than
         $5,000,000 per occurrence and in the aggregate: and

(iii)    workers'  compensation  insurance  covering all employees of SBC or its
         Affiliates to the extent required by any Laws.

(b) SBC shall pay all premiums for the insurance  coverage which SBC is required
to procure and maintain under this Sublease.  Each insurance  policy:  (i) shall
name TowerCo as an additional insured; provided that such requirement shall only
apply to liability policy and shall have no application to workers' compensation
policies;  and (ii) shall  provide  that the  policy  cannot be  canceled  as to
TowerCo  except after the insurer  endeavors  to give TowerCo  thirty (30) days'
written notice of cancellation. TowerCo agrees that SBC may, at SBC's option and
election,  participate in the self-insurance  program of SBC Communications Inc.
or otherwise  self-insure  to the extent  reasonable  in light of the  financial
condition of SBC from time to time with respect to all or a portion of the risks
required to be insured against by SBC under this Section 23. If SBC elects to be
covered by and participate in its self insurance and risk  management  programs,
SBC shall notify TowerCo of such election.  From time to time,  upon  reasonable
request by TowerCo, SBC shall furnish to TowerCo the information  concerning its
risk  management and self insurance  policies and programs in effect at the time
of such request.
<PAGE>   47
                                                                              45

(c) For each Site,  TowerCo shall procure,  and shall maintain in full force and
effect at all times during the Term as to the  applicable  Site,  the  following
types  of  insurance  with  respect  to  each  Site,  including  the  Tower  and
Improvements thereon, paying as the same become due all premiums therefor:

(i)      commercial  general public  liability  insurance  insuring  against all
         liability  of  TowerCo  and  TowerCo's  officers,   employees,  agents,
         licensees  and invitees  arising out of, by reason of or in  connection
         with the use,  occupancy  or  maintenance  of each  Subleased  Property
         (including Tower and the  Improvements),  in an amount of not less than
         $1,000,000  for bodily injury or property  damage or as a result of one
         occurrence,  and not less than $2,000,000 for bodily injury or property
         damage in the aggregate.

(ii)     umbrella or excess  liability  insurance with limits not less than
         $5,000,000 per occurrence and in the aggregate; and

(iii)    Insurance in an amount not less than full replacement cost of the Tower
         and  Improvements  of each Site,  against  direct and indirect  loss or
         damage by fire and all other  casualties  and risks  covered under "All
         Risk" insurance; and

(iv)     workers'  compensation  insurance  covering all employees of TowerCo or
         its Affiliates to the extent required by any Laws.

(d) TowerCo shall pay all premiums for the insurance  coverage  which TowerCo is
required to procure and maintain under this Sublease.  Each insurance policy (i)
shall name SBC and the  applicable  Sublessor as additional  insureds;  provided
that such  requirement  shall only apply to  liability  policy and shall have no
application to workers' compensation  policies;  and (ii) shall provide that the
policy cannot be canceled as to SBC and the  applicable  Sublessor  except after
the insurer gives SBC ten (10) days' written notice of cancellation.  If TowerCo
elects  to be  covered  by  and  participate  in its  self  insurance  and  risk
management  programs  or those of  SpectraSite  Communications  Inc.  or TowerCo
Parent as permitted in Section 23(f), TowerCo shall notify SBC of such election.
From time to time, upon reasonable  request by SBC, TowerCo shall furnish to SBC
the information  concerning its risk management and self insurance  policies and
programs in effect at the time of such request.

(e) All policy  amounts  set forth in this  Section 23 shall be reset every five
(5) years  during the Term to increase by an amount not less than the CPI Change
over the five (5) year period, except to the extent the Parties otherwise agree.

(f) TowerCo and SBC shall not, on their own initiative or pursuant to request or
requirement of any Space Subtenants or other Person, take out separate insurance
concurrent  in form or  contributing  in the event of loss with that required in
Section 23(c),  unless the other Party thereto is named therein as an additional
insured.  The Parties  agree that,  all policies of  insurance  required by this
Section 23 may contain  such loss  retention  provisions  or  deductibles  as is
reasonable in light of financial conditions of the Parties from time to time. In
addition and notwithstanding  anything to the contrary contained in this Section
23(c),  TowerCo  shall be permitted  to satisfy its  obligations  under  Section
(c)(iii)  hereof by  participating  in its self-  insurance  program  or that of
<PAGE>   48
                                                                              46

SpectraSite  Communications Inc. or TowerCo Parent for such risk coverage to the
extent  reasonable in light of the financial  condition of TowerCo,  SpectraSite
Communications Inc. or TowerCo Parent, as applicable, from time to time. TowerCo
and SBC shall  immediately  notify  the other  Party  hereto  whenever  any such
separate  insurance is taken out and shall deliver to SBC original  certificates
evidencing the same.

(g) As to the Subleased  Property and Reserved  Space of each Site, all policies
of  insurance  shall  be  written  on  companies  rated  A:VII  by AM  Best or a
comparable  rating  and  licensed  in the  State  where  such  Site is  located.
Certificates  evidencing  insurance shall be in a form reasonably  acceptable to
the recipient Party,  shall be delivered to such Party upon  commencement of the
Term and prior to expiration of such policy,  new  certificates  evidencing such
insurance, shall be delivered to such Party not less than twenty (20) days prior
to the  expiration of the then current  policy term.  The Parties agree that all
policies  of  insurance  required  by this  Section  23 may  contain  such  loss
retention  provisions  or  deductibles  as is  reasonable  in light of financial
conditions of the Parties.

(h)  Nothing in this  Section 23 shall  prevent  SBC or TowerCo  from  obtaining
insurance of the kind and in the amount provided for under this Section 23 under
a blanket insurance policy or policies (evidence thereof reasonably satisfactory
to the other Party shall be delivered to the other Party by the insuring  Party)
which may cover other properties owned or operated by the insuring Party as well
as the Subleased Property,  the Reserved Space or the Available Space; provided,
however,  that any such  policy of blanket  insurance  shall:  (i)  specify  the
amounts  thereof to the extent such amounts are used to meet the initial  limits
required  pursuant to this Section 23; and (ii)  provide  that such  policies of
blanket insurance shall, as respects the Subleased Property or Reserved Space of
each Site, contain the various  provisions  required of such an insurance policy
by the foregoing provisions of this Section 23.

SECTION 24.       Right of Substitution; Right of First Refusal.

(a)  Notwithstanding  anything to the contrary  contained herein, SBC shall have
the right (for the  benefit  of itself or any SBC  Affiliate)  to modify  and/or
replace, at SBC's expense, SBC's or any SBC Affiliates' Communications Equipment
at any Site provided said replacement Communications Equipment does not increase
the  weight  or  sail  area of  SBC's  or such  SBC  Affiliate's  Communications
Equipment (excluding the microwave dishes) on the Tower as of the date hereof by
more than ten percent (10%) and otherwise  does not cause overall Tower capacity
to be  exceeded.  SBC also shall have the right to make any  Alterations  to the
Site that it reasonably deems necessary to increase the capacity of or otherwise
augment,  strengthen or enhance a Tower (a "Sublessor Alteration").  Except with
respect to replacement or substitution of identical or  substantially  identical
equipment in the  identical  space,  the following  provisions  shall apply with
respect to any modification,  expansion,  replacement, addition or relocation of
Communications  Equipment  by SBC or any SBC  Affiliate  (in each case,  an "SBC
Alteration") and any Sublessor Alteration under this Sublease.

     (i)  Prior to commencing any such SBC  Alteration or Sublessor  Alteration,
          SBC shall obtain TowerCo's  written approval (which approval shall not
          be  unreasonably  withheld,  conditioned  or delayed,  so long as such
          modifications or replacements do not violate the applicable provisions
          of this  Sublease)  of detailed  plans and  specifications  accurately
          describing the proposed SBC Alteration or Sublessor Alteration.
<PAGE>   49
                                                                              47

          TowerCo   shall   either   approve  or   disapprove   such  plans  and
          specifications  in writing  within ten (10) business days of TowerCo's
          receipt of such plans and  specifications  failing which TowerCo shall
          be deemed to have approved SBC's' proposed plans and specifications.

     (ii) SBC agrees to comply with the reasonable  directions and  requirements
          which  TowerCo,  in its good faith  discretion,  may from time to time
          establish  in   connection   with  such   modifications,   expansions,
          replacements,  additions and relocations or Sublessor Alterations,  as
          the case may be, provided that such directions and requirements do not
          (i)   unreasonably   interfere   with  SBC's  or  the  applicable  SBC
          Affiliate's  ordinary  course  of  business  or  operations,  or  (ii)
          derogate or diminish any rights of SBC or any SBC Affiliate under this
          Sublease.  Such requirements may include,  at TowerCo's  request,  the
          preparation,  at SBC's cost and by a professional engineer licensed in
          the state in which the Site is located and reasonably  satisfactory to
          TowerCo,  of a structural analysis which details the effect of the SBC
          Alteration  or the  Sublessor  Alteration,  as the case may be, on the
          Tower and TowerCo's operations.

(b)  Notwithstanding  anything to the contrary  contained  herein, if during the
Term,  there is any Available Space in respect of the Subleased  Property of any
Site, then SBC shall have the Right of  Substitution  (for the benefit of itself
or any SBC  Affiliate) as to such  Available  Space.  The Right of  Substitution
pursuant to this Section  24(b) may be  exercised  by SBC at any time,  and from
time to time,  without limit,  upon written notice to TowerCo,  provided that no
such  relocation  shall impair the  structural  integrity  of the Tower.  If SBC
elects to exercise  its Right of  Substitution,  then,  upon  completion  of the
relocation of the Communications  Equipment of SBC or its Affiliate on the Tower
and  Improvements  thereon,  the  previously  existing  Reserved  Space  of  the
applicable  Site shall  automatically  be released by SBC or its  Affiliate  and
concurrently  therewith,   the  Available  Space  on  such  Site  to  which  the
Communications  Equipment  of SBC or its  Affiliate  has  been  relocated  shall
automatically  become and  constitute the Reserved Space of such Site subject to
Section  5. The terms of this  Section  24(b)  shall be  self-operative,  and no
further  instrument  shall be required to evidence any  Substitution;  provided,
however,  that upon the  request of either SBC or  TowerCo,  the  Parties  shall
promptly  execute  such  instruments  as may be  reasonably  required to further
evidence such Substitution, including without limitation an amendment to Exhibit
A or the applicable Site Designation Supplement.  SBC or its Affiliate shall, at
such Person's cost and expense,  complete the  relocation of its  Communications
Equipment  and return the  previously  existing  Reserved  Space to its original
condition, ordinary wear and tear excepted.

(c)  Notwithstanding  anything to the contrary  contained  herein, if during the
Term,  TowerCo intends to sublease any Available Space of the Subleased Property
of any  Site to a  potential  Space  Subtenant,  TowerCo  shall  notify  SBC and
Sublessor  by sending a copy of any  letter-offer,  letter of  intent,  or other
correspondence with the potential Space Subtenant together with a summary of the
economic terms of the proposed  sublease as contained in such  documents,  which
economic  terms  shall  include at least the number  and  location  of all Sites
subject to the proposed  lease or sublease,  the number,  type,  and location of
each antenna or other equipment on each Tower, the rent payable for such antenna
or other equipment on the Tower (including any escalation  provisions),  and the
term of each Space Subtenant sublease and any renewals thereof, which term in no
event shall bind Sublessor to a term  (including  renewals) which extends beyond
<PAGE>   50
                                                                              48

the Site Expiration  Outside Date of the Site in question unless Sublessor shall
have  consented  to  such  extended  term in  writing,  such  consent  not to be
unreasonably  withheld or delayed (the "Economic  Offer").  SBC may, in its sole
discretion,  by providing written notice thereof to TowerCo within ten (10) days
after  receipt of the  Economic  Offer from  TowerCo (x)  exercise  its Right of
Substitution  pursuant to Section 24(b) in respect of such Available  Space,  or
(y)  exercise  the Right of First  Refusal in respect  of such  Available  Space
pursuant to Sections  24(e) and (f), or (z)  exercise  both,  if with respect to
multiple  Sites.  If TowerCo  intends to  sublease  Available  Space at multiple
Sites,  SBC shall not be entitled to exercise  either its Right of  Substitution
and/or its Right of First Refusal as to any Available Space unless SBC exercises
such Right in respect of a minimum of the  greater of (i) five  percent  (5%) or
(ii) two (2) of the total number of Sites that TowerCo intends to sublease.

(d) If SBC exercises the Right of Substitution as to any Available  Space,  then
such  Available  Space shall  become  "Reserved  Space" for all purposes of this
Sublease and be subject to the  provisions  of Section 5. If SBC  exercises  the
Right of First Refusal as to such Available  Space,  then TowerCo shall sublease
the Available  Space to SBC (or the  designated  SBC Affiliate) for the sublease
term set forth in the  applicable  Economic  Offer.  For the first three hundred
(300)  times that SBC  exercises  its Right of First  Refusal  pursuant  to this
Section 24, the rent for such space shall be equal to the lesser of (i) the rent
provided for in the Economic Offer or (ii) an amount of rent that bears the same
proportion  to the SBC Leaseback  Charge  charged with respect to the Site(s) at
which such  Available  Space is located as the  Available  Space with respect to
which SBC exercises  the Right of First  Refusal bears to the Reserved  Space of
such Site(s).  With respect to any exercise by SBC of its Right of First Refusal
after the first three hundred  (300) times,  the rent for any  additional  space
leased  pursuant  to such  exercise of the Right of First  Refusal  shall be the
amount  specified in the Economic  Offer.  SBC (or the designated SBC Affiliate)
and TowerCo shall execute a sublease agreement in the form substantially similar
to the BTS Sublease (as defined in the Build-to-Suit  Agreement), as modified to
reflect the rental rate as herein above  provided  for and the sublease  term in
the applicable  Economic  Offer,  or in any other form acceptable to TowerCo and
SBC and, SBC shall, for all purposes of this Sublease,  become a Space Subtenant
of such Available Space at the rate prescribed above.

(e) If SBC fails to notify  TowerCo as to its  election to exercise its Right of
Substitution  or its Right of First Refusal  within the aforesaid  10-day period
under  Section  24(c),  then SBC's  options  referred  to in Section  24(c) with
respect to such  Available  Space shall expire and TowerCo  shall be entitled to
sublease such Available Space to the potential  Space  Subtenant  within 90 days
after SBC's receipt of the Economic Offer (which ninety (90) day period shall be
extended so long as TowerCo is diligently endeavoring to conclude such sublease)
upon,  in all  material  respects,  the terms and  conditions  contained  in the
applicable Economic Offer.

(f) If TowerCo  subleases any Available Space of any Site to the potential Space
Subtenant as provided  above,  TowerCo shall promptly  provide SBC a copy of the
final definitive sublease with the Space Subtenant (the "Final  Agreement").  If
the  economic  terms  of the  Final  Agreement  are not the same or  better  for
TowerCo,  in all material  respects,  than those of the Economic Offer, then, in
addition  to any other  remedies  SBC may  have,  SBC may  require  that the SBC
Leaseback  Charge  for the Site in  question  and all  other  economic  terms be
reduced to and conformed with those of the Final Agreement.
<PAGE>   51
                                                                              49

(g) If such  Available  Space has not been so subleased to such Space  Subtenant
within 90 days after  SBC's  receipt of the  applicable  Economic  Offer  (which
ninety  (90) day period  shall be  extended  so long as  TowerCo  is  diligently
endeavoring to conclude such sublease),  then the restrictions  provided in this
Section 24 shall again apply with respect to such Available  Space,  and TowerCo
shall have no right to sublease any such Available  Space without again offering
such  Available  Space to SBC in accordance  with the provisions of this Section
24.

SECTION 25.       Assignment and Subletting.

(a) Without the prior written consent of SBC, TowerCo may not assign,  sublease,
mortgage  or  otherwise  transfer  this  Sublease  or  any of  TowerCo's  rights
hereunder  in whole or in part  except  that (A)  TowerCo  may assign all of its
rights under this Sublease,  without SBC's consent, to any parent, subsidiary or
Affiliate of TowerCo;  (B) TowerCo may sublease Available Space provided that it
complies with the applicable provisions of Section 24(c) hereof; and (C) TowerCo
may,  with SBC's consent not to be  unreasonably  withheld  (provided  that such
consent  will not be required in the case of a  transaction  described in Clause
(A)), assign this Sublease in its entirety to a successor  corporation or entity
to TowerCo by way of merger,  consolidation  or other  reorganization  or to any
Person acquiring all or substantially all of TowerCo's assets;  provided that in
the case of an assignment  under  Subsection  (A) such assignee (i) is not a SBC
Competitor  and (ii)  assumes  all of  TowerCo's  obligations  hereunder,  which
assumption  need apply only with respect to  obligations  arising from and after
the date of such transfer; and in the case of an assignment under Subsection (C)
such  assignee  (i)  is a  Permitted  TowerCo  Transferee,  (ii)  is  not  a SBC
Competitor  and (iii)  assumes all of  TowerCo's  obligations  hereunder,  which
assumption  need apply only with respect to  obligations  arising from and after
the date of such  transfer;  provided  further  that  TowerCo may make a partial
assignment of this Sublease upon the prior written consent of SBC to be provided
in its sole and absolute discretion.  Upon any permitted assignment under (A) or
(C), TowerCo shall be released from its obligations under this Sublease from and
after the date of such assignment but shall not be released from any liabilities
arising prior to the date of such transfer.  Upon any permitted assignment under
Subsection  (C) above  (other than to any parent,  subsidiary  or  Affiliate  of
TowerCo),   TowerCo  Parent  shall,   with  SBC's  written  consent  not  to  be
unreasonably withheld, be released from its obligations under this Sublease from
and  after  the date of such  assignment  but  shall  not be  released  from any
liabilities  arising  prior to the date of such  transfer.  Notwithstanding  the
foregoing,  TowerCo may enter into Permitted  Subleasehold Pledges and Permitted
Subleasehold  Mortgages,  in which case the  Permitted  Subleasehold  Collateral
Assignee with respect  thereto shall have the right to exercise  remedies  under
any such  mortgage,  pledge,  hypothecation  or other  collateral  transfer in a
manner  consistent with the provisions of this and every other agreement between
TowerCo and SBC made in connection with this transaction.  TowerCo  acknowledges
that it shall not be permitted to enter into a Permitted  Subleasehold  Mortgage
with  respect to all or any  portion of a Site prior to the Closing of such Site
in accordance with Section 4.1 of the Agreement to Sublease.

(b) SBC and each Sublessor  shall have the  unrestricted  right during the Term,
subject to any required consent of any Ground Lessor, to sell, convey, transfer,
assign or otherwise  dispose  (but not to sublease  other than a sublease of the
<PAGE>   52
                                                                              50

Reserved Space to a SBC Affiliate which conducts its wireless  activities at the
Reserved Space,  which Sublease shall be permitted without TowerCo's consent) of
SBC's or such Sublessor's  interest in and to any Site (including SBC's or a SBC
Affiliate's interest in and to the Subleased Property of such Site), in whole or
in part (a "Transfer") to: (i) a SBC Affiliate;  (ii) a Permitted Transferee; or
(iii) any other Person (a "Non-Qualifying Transferee");  provided, however, that
with respect to subsections (ii) and (iii) above, neither SBC nor such Sublessor
may assign its interest in the Reserved  Space  except in  conjunction  with the
sale or  other  transfer  of all or a  portion  of an SBC  Affiliate's  wireless
business on a Site by Site basis,  and provided  further that SBC may not assign
its interest in the Reserved Space without transferring the corresponding Ground
Lease,  and vice versa.  Upon any  permitted  Transfer  of this  Sublease in its
entirety by SBC or any Sublessor,  the assignee shall assume all of SBC's or any
Sublessor's  obligations  hereunder  arising  from  and  after  the date of such
Transfer.  In  the  event  of  any  Transfer  by  SBC  or a SBC  Affiliate  to a
Non-Qualifying  Transferee  or to a  SBC  Affiliate  which  is  not a  Permitted
Transferee, SBC shall not be relieved of its obligations hereunder. In the event
of any other  Transfer by SBC or a SBC  Affiliate,  all  obligations  under this
Sublease of the Person  effecting  such Transfer  shall cease and terminate with
respect to the Site or Sites in  question,  excluding  any  liabilities  arising
prior to the date of such  Transfer,  and TowerCo  shall look only and solely to
the Person to whom SBC's or such SBC  Affiliate's  interest  in and to such Site
(including  SBC's  or such  SBC  Affiliate's  interest  in and to the  Subleased
Property  thereof or any portion  thereof) is Transferred for performance of all
of SBC's or such SBC Affiliate's duties and obligations under this Sublease with
respect to such Site arising after the date of such Transfer  (provided that the
transferee assumes all of SBC's or such SBC Affiliate's  obligations  hereunder,
which  assumption  need only apply with respect to obligations  arising from and
after the date of such Transfer or, in the case of a partial assignment,  enters
into the  "New  Sublease  Documents,"  as  defined  below).  Upon any  permitted
Transfer of this Lease in whole or in part under clause 25(b)(ii) (other than an
assignment  to any parent,  subsidiary  or  Affiliate  of  Wireless  Guarantor),
Wireless  Guarantor shall be released from its  obligations  under this Sublease
from and after the date of such  Transfer  with respect to the Site(s) which are
the  subject of such  Transfer  but shall not be released  from any  liabilities
arising prior to the date of such  Transfer.  For purposes of the  provisions of
this Section 25(b) relating to the release of a Sublessor, SBC, an SBC Affiliate
or Wireless  Guarantor  from their  respective  obligations  under the  Sublease
following  a  "Transfer",  the term  "Transfer"  shall not  include a  mortgage,
pledge,  lien or other similar collateral  assignment for security purposes or a
sublease.

         Notwithstanding  the foregoing,  in the event of a Transfer by SBC or a
SBC Affiliate to a Non-Qualifying  Transferee, if either (x) such Non-Qualifying
Transferee  ultimately  becomes a  Permitted  Transferee  or (y)  subject to the
consent of TowerCo,  which consent may not be unreasonably withheld, no unwaived
event of default on the part of such Non-Qualifying Transferee occurs in respect
of such  Sites  for three (3)  years  after  the date of such  Transfer  to such
transferee,  SBC or such SBC Affiliate,  as applicable,  and Wireless  Guarantor
shall be released  (effective  as of the date on which either of the  conditions
set forth in (x) or (y) is satisfied)  from any and all  obligations  under this
Sublease as to such Sites for  obligations  arising after the effective  date of
such  release,  and upon SBC's  request  TowerCo  shall  confirm such release in
writing.
<PAGE>   53
                                                                              51

         Except as expressly  provided in Section  25(b),  wherever  under or in
connection  with this  Sublease SBC or any SBC  Affiliate  Transfers  its right,
title or interest,  in whole or in part, in or to this Sublease or any Site, SBC
or such SBC Affiliate  shall be released from performing any and all obligations
under this  Sublease  arising  after the date of such Transfer in respect of the
right,  title or interest so Transferred and under the applicable  Ground Lease,
and  TowerCo  hereby  acknowledges  such  release.  At or prior  to any  partial
assignment of this  Sublease,  TowerCo and such assignee shall have entered into
one or more  agreements,  including  without  limitation,  a  sublease  and site
designation  supplements  (collectively,  the "New  Sublease  Documents"),  that
afford TowerCo and such assignee  relative rights,  vis-a-vis  TowerCo's or such
assignee's  rights and  obligations  under the New  Sublease  Documents  no less
favorable to TowerCo and such assignee  than those  afforded by the Sublease and
the Site  Designation  Supplements with respect to the rights and obligations of
SBC and TowerCo, and are otherwise in form and substance reasonably satisfactory
to TowerCo and such assignee.

(c) Without  limiting the  generality of the other  provisions of this Sublease,
any assignment of interest pursuant to this Sublease and any sublease  permitted
under ss. 25(a) shall be  effectuated  by ten (10) days' written  notice of such
assignment  or  sublease,  which  notice shall  include the name,  address,  and
telephone  number of the assignee.  Each Party hereby agrees that any attempt of
such Party to assign or otherwise  Transfer its interest in this Sublease or any
of its rights  hereunder,  in whole or in part, in violation of Section 25 shall
constitute a default under this Sublease and shall be null and void ab initio

(d) In the event that a Ground  Lease  restricts  TowerCo's  ability to sublease
space on the Leased Property,  the applicable Sublessor agrees that it shall use
commercially  reasonable  efforts  to  assist  and  cooperate  with  TowerCo  in
obtaining any such necessary consents,  at TowerCo's sole cost and expense, from
the Ground Lessor.

SECTION 26.       Estoppel Certificate.

         Either  Party,  from time to time upon ten (10) days' prior  request by
the other Party, shall execute, acknowledge and deliver to the requesting Party,
or to a person designated by such requesting  Party, a certificate  stating that
this  Sublease  is  unmodified  and in full  effect  (or,  if  there  have  been
modifications,  that this  Sublease is in full effect as  modified,  and setting
forth such  modifications)  and the dates to which  Rent and other sums  payable
under this Sublease have been paid,  and either stating that to the knowledge of
the signer of such  certificate no default exists  hereunder or specifying  each
such default of which the signer has knowledge.  The requesting  Party,  at such
Party's  cost and  expense,  shall cause such  certificate  to be  prepared  for
execution by the requested Party. Any such certificate may be relied upon by any
prospective  Permitted  Collateral  Assignee,  Mortgagee  or  purchaser  of  the
Subleased Property of each Site.

SECTION 27.       Holding Over.

         If TowerCo remains in possession of the Subleased  Property of any Site
after expiration or termination of the then current Term as to such Site without
any express written  agreement by SBC, then TowerCo shall be and become a tenant
at  sufferance,  and there shall be no renewal or extension of this  Sublease by
operation of law.  This section  shall be deemed to be an  "agreement  expressly
providing  otherwise"  within the meaning of Section  232-c of the Real Property
law of the State of New York.
<PAGE>   54
                                                                              52

SECTION 28.       Rights of Entry and Inspection.

(a) TowerCo shall permit SBC and SBC's representatives,  agents and employees to
enter  the  Subleased  Property  of any  Site at all  reasonable  times  for the
purposes of inspecting such Subleased Property,  showing the Site to prospective
purchasers and Mortgagees,  making any repairs or replacements or performing any
maintenance, and performing any work on the Site that SBC may consider necessary
to prevent or cure  deterioration,  waste or unsafe conditions.  Nothing in this
Section 28 shall imply or impose any duty or  obligation  upon SBC to enter upon
any Site at any time for any purpose,  or to inspect the  Subleased  Property at
any time, or to perform,  or pay the cost of, any work which TowerCo is required
to perform  under any  provision of this  Sublease,  and SBC has no such duty or
obligation.

(b) SBC shall permit TowerCo and TowerCo's  representatives to inspect SBC's and
the SBC Affiliates' Communications Equipment for the purpose, in the event of an
Emergency  only, for making repairs or  replacements  to address such Emergency.
The foregoing shall not limit TowerCo's rights pursuant to Section 7 hereof.

SECTION 29. A Party's Right to Act for the Other Party; SBC Set-Off Right.

(a) In addition to and not in  limitation of any other remedy SBC may have under
this Sublease,  if TowerCo fails to make any payment or to take any other action
(or to cause any Space  Subtenant to take any action) when and as required under
this Sublease, including without limitation Sections 11(a) and 17 and Exhibit C,
SBC may,  without demand upon TowerCo and without  waiving or releasing  TowerCo
from any duty,  obligation  or  liability  under  this  Sublease,  make any such
payment or take any such other  action  required  of TowerCo.  Unless  TowerCo's
failure  results in or relates to an Emergency,  SBC shall give TowerCo at least
ten (10) days prior written  notice of SBC's  intended  action and TowerCo shall
have the right to cure such failure  within such 10-day  period.  No such notice
shall be required in the event of an  Emergency.  The actions which SBC may take
shall include, but are not limited to, the performance of maintenance or repairs
and the making of replacements to the Towers and  Improvements on each Site (and
SBC shall  have full  access to the Sites  for such  purpose),  the  payment  of
insurance  premiums  which TowerCo is required to pay under this  Sublease,  the
payment of Ground Rents which TowerCo is required to pay under the Ground Leases
and the payment of Taxes and Assessments  which TowerCo is required to pay under
this  Sublease.  SBC may pay all  incidental  costs  and  expenses  incurred  in
exercising  its rights  hereunder,  including,  without  limitation,  reasonable
attorneys' fees and expenses, penalties,  re-instatement fees, late charges, and
interest.  An amount  equal to one hundred  twenty  percent  (120%) of the total
amount of the costs and expenses  (including salaries and benefits of employees)
incurred  by SBC or SBC  Affiliates  in  accordance  with  this  Section  29, is
referred to as the "Reimbursable  Maintenance Expenses" of SBC, shall be due and
payable by TowerCo upon demand and bear interest at the rate of eighteen percent
(18%) per annum from the date of demand  until paid by  TowerCo.  SBC shall have
the right to set off against  any SBC  Leaseback  Charges  due under  Section 10
hereof the amount of any Reimbursable Maintenance Expenses and any other amounts
due and  owing  by  TowerCo  or  TowerCo  Parent  to SBC or any  SBC  Affiliates
hereunder.
<PAGE>   55
                                                                              53

(b) For  purposes of this  Section,  the term  "Emergency"  means any event that
causes, has caused or is likely to cause, (i) any bodily injury, personal injury
or property damage;  (ii) the suspension,  revocation,  termination or any other
adverse  material effect as to any licenses  and/or  permits;  (iii) any adverse
effect  on the  ability  of SBC or its  Affiliates  or any Space  Subtenants  to
operate Communications  Equipment;  or (iv) any failure of any Site to comply in
any material respect with applicable Laws.

SECTION 30.       Defaults and Remedies.

(a)      The following events shall constitute events of default by SBC:

     (i)  If SBC or a SBC  Affiliate  fails to perform any material  obligations
          pursuant to the  applicable  Ground Lease for a Site that SBC or a SBC
          Affiliate  is expressly  required to perform  pursuant to the terms of
          this  Sublease and shall not cure such failure by the later of (x) the
          expiration  of any  applicable  cure  period,  or (y) thirty (30) days
          after TowerCo gives SBC written notice thereof; or

     (ii) if SBC, or with respect to any covenant  required to be complied  with
          by any SBC Affiliate, such SBC Affiliate,  shall materially violate or
          breach,  or shall  materially  fail to fully and  completely  observe,
          keep, satisfy, perform and comply with, any agreement, term, covenant,
          condition,  requirement,  restriction or provision of this Sublease in
          respect of any Site (which  violations,  breaches  or failures  may be
          different for each Site), and shall not cure such violation, breach or
          failure within thirty (30) days after TowerCo gives SBC written notice
          thereof,  or, if such failure shall be incapable of cure within thirty
          (30) days, if SBC shall not commence to cure such failure  within such
          thirty (30) day period and  continuously  prosecute the performance of
          the same to completion with due diligence; or

     (iii)Subject to Section 30(i), SBC breached any material  representation or
          warranty in this Sublease as to any Site as of the date when made.

     (iv) if SBC becomes  insolvent  as defined in the Uniform  Commercial  Code
          under the Laws  applicable to this Sublease or makes an assignment for
          the benefit of  creditors;  or if any action is brought by SBC seeking
          its   dissolution   or  liquidation  of  its  assets  or  seeking  the
          appointment of a trustee, interim trustee, receiver or other custodian
          for any of its property;  or if SBC  commences a voluntary  proceeding
          under  the  Federal  Bankruptcy  Code;  or if  any  reorganization  or
          arrangement  proceeding  is  instituted  by SBC  for  the  settlement,
          readjustment,  composition  or  extension of any of its debts upon any
          terms;  or if any  action or  petition  is  otherwise  brought  by SBC
          seeking  similar  relief or alleging that it is insolvent or unable to
          pay its debts as they mature;  or if any action is brought against SBC
          seeking  its  dissolution  or  liquidation  of any of its  assets,  or
          seeking the  appointment of a trustee,  interim  trustee,  receiver or
          other  custodian  for any of its  property,  and any  such  action  is
          consented to or acquiesced in by SBC or is not dismissed within ninety
          (90) days after the date upon which it was instituted; or if any
<PAGE>   56
                                                                              54

          proceeding under the Federal Bankruptcy Code is instituted against SBC
          and (1) an order for relief is entered in such proceeding, or (2) such
          proceeding is consented to or acquiesced in by SBC or is not dismissed
          within  ninety (90) days after the date upon which it was  instituted;
          or if any  reorganization  or  arrangement  proceeding  is  instituted
          against SBC for the settlement, readjustment, composition or extension
          of any of its debts upon any terms,  and such  proceeding is consented
          to or acquiesced in by SBC or is not dismissed within ninety (90) days
          after  the date  upon  which it was  instituted;  or if any  action or
          petition is otherwise  brought  against SBC seeking  similar relief or
          alleging that it is insolvent,  unable to pay its debts as they mature
          or generally  not paying its debts as they become due, and such action
          or  petition  is  consented  to or  acquiesced  in by  SBC  or is  not
          dismissed  within  thirty  (30) days  after the date upon which it was
          brought.

     (v)  if  any  Sublessor   becomes  insolvent  as  defined  in  the  Uniform
          Commercial Code under the Laws applicable to this Sublease or makes an
          assignment  for the benefit of creditors;  or if any action is brought
          by a Sublessor seeking its dissolution or liquidation of its assets or
          seeking the  appointment of a trustee,  interim  trustee,  receiver or
          other custodian for any of its property; or if a Sublessor commences a
          voluntary  proceeding  under the Federal  Bankruptcy  Code;  or if any
          reorganization or arrangement  proceeding is instituted by a Sublessor
          for the settlement,  readjustment,  composition or extension of any of
          its debts upon any terms;  or if any action or petition  is  otherwise
          brought by a Sublessor  seeking  similar relief or alleging that it is
          insolvent or unable to pay its debts as they mature;  or if any action
          is brought against a Sublessor  seeking its dissolution or liquidation
          of any of its assets, or seeking the appointment of a trustee, interim
          trustee,  receiver or other custodian for any of its property, and any
          such action is consented to or acquiesced  in by such  Sublessor or is
          not dismissed within ninety (90) days after the date upon which it was
          instituted;  or if any proceeding under the Federal Bankruptcy Code is
          instituted  against a Sublessor and (1) an order for relief is entered
          in  such  proceeding,  or  (2)  such  proceeding  is  consented  to or
          acquiesced in by such Sublessor or is not dismissed within ninety (90)
          days  after  the  date  upon  which  it  was  instituted;  or  if  any
          reorganization  or  arrangement  proceeding  is  instituted  against a
          Sublessor for the settlement,  readjustment,  composition or extension
          of any of its debts upon any terms,  and such  proceeding is consented
          to or  acquiesced  in by such  Sublessor  or is not  dismissed  within
          ninety  (90) days after the date upon which it was  instituted;  or if
          any  action or  petition  is  otherwise  brought  against a  Sublessor
          seeking similar relief or alleging that it is insolvent, unable to pay
          its debts as they  mature or  generally  not  paying its debts as they
          become due, and such action or petition is consented to or  acquiesced
          in by such Sublessor or is not dismissed within thirty (30) days after
          the date upon which it was brought.

(b) Upon the occurrence of any event of default by SBC under Section  30(a)(iv),
TowerCo may terminate this Sublease by giving SBC written notice of termination,
and this Sublease  shall be terminated at the time  designated by TowerCo in its
notice of  termination  to SBC  whereupon  SBC shall be  obligated  to refund to
TowerCo all Rent for the rental  periods  occurring  after the effective date of
such  termination.  Upon the  occurrence  of any event of  default  by SBC under
Sections 30(a)(i)-(a)(iii) as to the Reserved Space of a Site or with respect to
a Sublessor  under Section  30(a)(v),  TowerCo may terminate this Sublease as to
the  applicable  Site by giving  SBC  written  notice of  termination,  and this
Sublease shall be terminated as to the applicable Site at the time designated by
TowerCo in its notice of  termination to SBC whereupon SBC shall be obligated to
refund to TowerCo the Rent allocable to such Site for the rental periods
<PAGE>   57
                                                                              55

occurring  after the effective  date of such  termination.  Notwithstanding  the
foregoing, if SBC fails to pay any portion of a SBC Leaseback Charge because SBC
or a SBC  Affiliate,  acting in good faith,  reduced the amount of SBC Leaseback
Charges  paid to TowerCo  in giving  effect to a  mistaken  belief  that it made
Reimbursable  Maintenance  Expenses  under  Section  29(a)  that  SBC  or a  SBC
Affiliate was not permitted to make,  such failure shall not constitute an event
of default hereunder.  Upon TowerCo's demand after any resolution of any dispute
as to the amount of such Reimbursable  Maintenance Expenses,  SBC shall pay such
amount to TowerCo,  with interest  thereon at the rate of eighteen percent (18%)
per annum, from the date such amount was due until the date paid.

(c) TowerCo's remedy stated in Section 30(b) above shall not preclude pursuit of
any other  remedy or remedies  provided in this  Sublease or any other remedy or
remedies provided for or allowed by law or in equity, separately or concurrently
or in any combination.

(d)      The following events shall constitute events of default by TowerCo:

     (i)  If TowerCo fails to timely pay Ground Rent as provided in Section 3(d)
          or  otherwise  fails to make payment of any amount due  hereunder  and
          such failure  continues  for ten (10) days after the date such payment
          was due and payable or,  with  respect to the payment of Ground  Rent,
          for such longer grace period as may be provided for in the  applicable
          Ground Lease, or

     (ii) (x) TowerCo shall  materially  violate or breach,  or shall materially
          fail to fully and  completely  observe,  keep,  satisfy,  perform  and
          comply with, any term, covenant, condition,  requirement,  restriction
          or  provision  of  this  Sublease  with  respect  to any  Site  (which
          violations,  breaches or failures may be different for each Site), and
          shall not cure such  violation,  breach or failure  within thirty (30)
          days  after SBC gives  TowerCo  written  notice  thereof,  or, if such
          failure  can be cured,  but not within  thirty  (30) days,  if TowerCo
          shall not  commence to cure such  failure  within such thirty (30) day
          period  and  continuously  prosecute  the  performance  of the same to
          completion  with  due  diligence  or  (y)  the  aggregate   amount  of
          Reimbursable  Maintenance  Expenses in respect of any Site pursuant to
          Section 29(a) exceeds  $4,000 on at least two  occurrences  within the
          same Sublease Year, whether or not reimbursed by TowerCo; or

     (iii)Subject to Section  30(i),  any  representation  or  warranty  made by
          TowerCo in this Sublease  shall be false or misleading in any material
          respect on the date as of which made (or deemed made); or

     (iv) TowerCo or TowerCo Parent shall materially violate or breach, or shall
          materially  fail to fully and  completely  observe,  keep,  satisfy or
          perform any  obligation  for money  borrowed  involving  not less than
          $5,000,000  in  principal  amount in  connection  with this  Sublease,
          including,  without  limitation,  Mortgages,  or any obligation  under
          notes  payable  or drafts  accepted,  or any  obligation  of any other
          agreement,  term or condition  contained in any indenture or agreement
          under which any such  obligation is created,  guaranteed or secured if
          the effect of such default is to cause such  obligation  to become due
          prior to its stated maturity;
<PAGE>   58
                                                                              56

     (v)  If TowerCo becomes insolvent as defined in the Uniform Commercial Code
          under the Laws  applicable  to this  Sublease  or any Site or makes an
          assignment  for the benefit of creditors;  or if any action is brought
          by TowerCo  seeking its  dissolution  or  liquidation of its assets or
          seeking the  appointment of a trustee,  interim  trustee,  receiver or
          other  custodian  for any of its property;  or if TowerCo  commences a
          voluntary  proceeding  under the Federal  Bankruptcy  Code;  or if any
          reorganization or arrangement  proceeding is instituted by TowerCo for
          the settlement,  readjustment,  composition or extension of any of its
          debts  upon any  terms;  or if any  action or  petition  is  otherwise
          brought by  TowerCo  seeking  similar  relief or  alleging  that it is
          insolvent or unable to pay its debts as they mature;  or if any action
          is brought  against  TowerCo seeking its dissolution or liquidation of
          any of its assets,  or seeking the  appointment of a trustee,  interim
          trustee,  receiver or other custodian for any of its property, and any
          such  action is  consented  to or  acquiesced  in by TowerCo or is not
          dismissed  within  ninety  (90) days  after the date upon which it was
          instituted;  or if any proceeding under the Federal Bankruptcy Code is
          instituted  against  TowerCo and (1) an order for relief is entered in
          such proceeding,  or (2) such proceeding is consented to or acquiesced
          in by TowerCo or is not  dismissed  within  ninety (90) days after the
          date  upon  which  it  was  instituted;  or if any  reorganization  or
          arrangement   proceeding  is  instituted   against   TowerCo  for  the
          settlement, readjustment, composition or extension of any of its debts
          upon any terms,  and such  proceeding is consented to or acquiesced in
          by TowerCo or is not dismissed  within ninety (90) days after the date
          upon  which  it  was  instituted;  or if any  action  or  petition  is
          otherwise  brought  against TowerCo seeking similar relief or alleging
          that it is  insolvent,  unable  to pay its  debts  as they  mature  or
          generally  not paying its debts as they become due, and such action or
          petition  is  consented  to or  acquiesced  in by  TowerCo  or is  not
          dismissed  within  thirty  (30) days  after the date upon which it was
          brought; or

     (vi) If the leaseback to SBC of the Reserved  Space at any Site is rejected
          by TowerCo under Section 365 of the Federal Bankruptcy Code.

(e) Upon the  occurrence of any event of default by TowerCo under Section 30(d),
Section  14(c) or Section 14(d) in respect of any Site,  SBC may terminate  this
Sublease  as to  the  applicable  Site  by  giving  TowerCo  written  notice  of
termination,  and this Sublease shall be terminated as to such Site, at the time
designated  by SBC in its notice of  termination  to TowerCo,  unless  otherwise
provided  herein.  Upon the occurrence of events of default (whether of the same
or different types) by TowerCo under Section 30(d) in respect of more than fifty
(50) Sites during any consecutive five (5) year period or portion  thereof,  SBC
may terminate this Sublease as to all Sites by giving TowerCo  written notice of
termination,  and this Sublease  shall be terminated as to all Sites at the time
designated by SBC in its notice of termination to TowerCo.

(f) SBC and each  Sublessor  may pursue any remedy or remedies  provided in this
Sublease,  including without limitation Section 30(e), or any remedy or remedies
provided for or allowed by law or in equity,  separately or  concurrently  or in
any combination,  including,  without  limitation,  (i) specific  performance or
other equitable remedies;  (ii) money damages arising out of such default; (iii)
SBC or the applicable SBC Affiliate may exercise the Withdrawal  Right as to any
Site immediately and without further act,  pursuant to Section 9; or (iv) SBC or
<PAGE>   59
                                                                              57

the  applicable   Sublessor  may  perform,  on  behalf  of  TowerCo,   TowerCo's
obligations  under the terms of this  Sublease  pursuant to Section 29, in which
event SBC shall have the right to set off all Reimbursable  Maintenance Expenses
against  the SBC  Leaseback  Charges  SBC is  required  to pay. If the amount of
Reimbursable  Maintenance  Expenses exceeds the SBC Leaseback Charges payable by
SBC  hereunder  and TowerCo does not  reimburse  SBC or each  Sublessor the full
amount of such  excess  within  ten (10) days  following  SBC's  written  demand
therefor,  SBC and the  Sublessors may terminate this Sublease in respect of all
or any of the Sites pursuant to Section 30(e) and shall be reimbursed thereof.

(g) A  Party's  pursuit  of any  one or more of the  remedies  provided  in this
Sublease shall not constitute an election of remedies  excluding the election of
another  remedy or other  remedies,  or a  forfeiture  or waiver of any  amounts
payable under this Sublease as to the applicable Site by such Party or waiver of
any  relief or damages  or other  sums  accruing  to such Party by reason of the
other Party's failure to fully and completely keep,  observe,  perform,  satisfy
and  comply  with  all  of  the  agreements,   terms,   covenants,   conditions,
requirements,  provisions and  restrictions  of this  Sublease.  Notwithstanding
anything to the contrary contained herein,  neither Party shall be liable to the
other  parties  for  indirect,  incidental,  special or  consequential  damages,
including but not limited to lost profits,  however arising, even if a Party has
been advised of the possibility of such damages.

(h) Either  Party's  forbearance  in pursuing or  exercising  one or more of its
remedies shall not be deemed or construed to constitute a waiver of any event of
default or of any  remedy.  No waiver by either  Party of any right or remedy on
one  occasion  shall be  construed  as a waiver  of that  right or remedy on any
subsequent  occasion  or as a  waiver  of any  other  right  or  remedy  then or
thereafter existing. No failure of either Party to pursue or exercise any of its
powers,  rights or remedies or to insist upon strict and exact compliance by the
other  Party  with  any  agreement,  term,  covenant,  condition,   requirement,
provision or restriction of this Sublease, and no custom or practice at variance
with the terms of this  Sublease,  shall  constitute a waiver by either Party of
the right to demand strict and exact compliance with the terms and conditions of
this Sublease.

(i) Notwithstanding  the foregoing,  no event of default shall be deemed to have
occurred  in respect of SBC under  Section  30(a)(iii)  or in respect of TowerCo
under  Section  30(d)(iii),  if the other Party gives  notice after one (1) year
following:

     (i)  the  applicable  Site  Commencement  Date with  respect to the Site in
          question in the case of a  representation  or warranty made under this
          Sublease or the  applicable  Site  Designation  Supplement,  as to any
          Site;

     (ii) the date hereof,  in the case of any other  representation or warranty
          made under this Sublease; or

     (iii)in the case of  representation or warranty made under the Agreement to
          Sublease, as provided therein.

(j) Upon the occurrence of any event of default by TowerCo under this Section 30
in respect of any Site,  the  applicable  Sublessor  shall give every  Permitted
Subleasehold Collateral Assignee of which Sublessor has written notice a written
<PAGE>   60
                                                                              58

notice of, and an opportunity to cure within  forty-five (45) days after receipt
of such Sublessor's written notice of default,  all existing defaults hereunder.
In the  event  the  Permitted  Subleasehold  Collateral  Assignee  fails to cure
defaults as to any Site within such forty-five  (45) day period,  such Sublessor
may  terminate  this  Agreement as to such Site.  The parties  hereto agree that
prior to the date upon  which such  Sublessor  has the right to  terminate  this
Agreement as to such Site, any Permitted  Subleasehold  Collateral Assignee may,
at its option,  be substituted and replace  TowerCo as Sublessee  hereunder (and
TowerCo agrees to relinquish  all rights  hereunder) by assuming and agreeing to
be bound by each and every term, covenant,  condition,  agreement,  requirement,
restriction  and  provision  set forth in this  Agreement,  and  subject  to all
rights,  title, and interest of the applicable  Sublessor;  provided that in the
event there have been more than fifty (50) events of default within any five (5)
year period and SBC gives notice under  Section  30(d) hereof of its election to
terminate this Sublease,  such Permitted  Subleasehold  Collateral Assignee may,
prior to termination of this Agreement by the applicable Sublessor, transfer its
interests  under  this  Agreement  in  its  entirety  after  providing  evidence
satisfactory to SBC that the proposed  assignee is not an SBC Competitor and has
appropriate  industry  experience,  the capability and the financial  ability to
perform the  obligations  of TowerCo  hereunder  and under any other  agreements
relating to or concerning  the  transactions  between SBC and TowerCo,  in which
event this Sublease shall not terminate.

SECTION 31.       Quiet Enjoyment.

         TowerCo  shall,  subject to the terms and  conditions of this Sublease,
peaceably and quietly hold and enjoy the Subleased  Property of each Site during
the Term without  hindrance or interruption  from SBC or any Person claiming by,
through  or under  SBC,  so long as no  event of  default  has  occurred  and is
continuing hereunder.
SECTION 32.       No Merger.

         There shall be no merger of this Sublease or the subleasehold  interest
or estate created by this Sublease in any Site with the superior  estate held by
the Sublessor thereof,  by reason of the fact that the same person or entity may
acquire, own or hold, directly or indirectly,  both the subleasehold interest or
estate created by this Sublease in any Site and such superior  estate;  and this
Sublease  shall  not be  terminated,  in  whole  or as to any  Site,  except  as
expressly provided herein.

SECTION 33.       Broker and Commission.

(a) All negotiations in connection with this Sublease have been conducted by and
between TowerCo and SBC without the intervention of any person or other Party as
agent or broker other than Goldman,  Sachs & Co. which is advising SBC's parent,
SBC   Communications   Inc.,  in  connection  with  this  Sublease  and  related
transactions.

(b)  TowerCo  and SBC  warrant  and  represent  to each  other that there are no
broker's  commissions or fees payable in connection with this Sublease by reason
of their  respective  dealings,  negotiations or  communications  other than the
advisor's  fee  payable to  Goldman,  Sachs & Co.  which shall be payable by SBC
Communications  Inc. TowerCo and SBC shall, and do hereby indemnify,  defend and
<PAGE>   61
                                                                              59

hold  harmless  each other from and against  the Claims of any and all  brokers,
agents and other intermediaries  alleging a commission,  fee or other payment to
be owing by reason of their respective dealings,  negotiations or communications
in connection with this Sublease.

SECTION 34.       Recording of Memorandum of Ground Lease.

(a) Subject to the applicable provisions of the Agreement to Sublease,  upon the
execution of this  Sublease,  TowerCo may, at its cost and expense (i) cause the
Ground  Leases or  memorandum  of Ground Leases for the Sites to be filed in the
appropriate  County  property  records,  unless  such  Ground  Leases  expressly
prohibit such recording;  and (ii) promptly following the execution of each Site
Designation  Supplement,  cause a  memorandum  of sublease  with  respect to the
applicable  Site to be filed in the appropriate  County property  records unless
the Ground Lease for the applicable Site prohibits such recording.

(b) In  addition  to and  not in  limitation  of any  other  provision  of  this
Sublease,  the Parties shall have the right to review and make  corrections,  if
necessary, to any and all exhibits hereto or to the Site Designation Supplements
or to the  memorandum  of  sublease  after the date  hereof.  After  making such
corrections, TowerCo shall re-record such memorandum of sublease to reflect such
corrections, if requested by either Party. The Parties shall cooperate with each
other to cause changes to be made in the  documentation for any Site, and in the
Site  Designation  Supplement or to the memorandum of sublease for such Site, if
such changes are requested by either Party to evidence any permitted  changes in
the description of the Reserved Space respecting such Site,  including,  without
limitation  changes in SBC's or such SBC Affiliate's  antennas or other parts of
its  Communications  Facility at such Site. In addition to and not in limitation
of the  foregoing,  either Party shall have the right,  at its sole expense,  to
cause any  amendment to such  memorandum  of Sublease to be recorded,  including
without limitation in connection with such changes.

SECTION 35.       Purchase Options.

(a) Right to Purchase.  If this Sublease shall not have been earlier terminated,
or an event of default by TowerCo  shall not have  occurred and be continuing at
the date of option  exercise  or the date  fixed for  purchase  (as such date is
specified below), TowerCo shall have an option,  exercisable no earlier than one
hundred  eighty (180) days and no later than one hundred twenty (120) days prior
to each Site Expiration  Outside Date (the "Option Trigger  Window") to elect to
purchase  all (but not less  than all) of the Sites  (excluding,  in all  cases,
SBC's Improvements and any Space Subtenant's  Improvements on such Site(s)) then
subleased under this Sublease which have the same Site Expiration  Outside Date,
at a purchase price equal to the aggregate of the Option  Purchase Price Amounts
and any additional  amounts  determined  pursuant to Section 3(i) hereof for the
applicable  Sites and on the other  terms and subject to the  conditions  herein
specified.  TowerCo may exercise  such  purchase  option by submitting to SBC in
writing an offer for all of such Sites  within the Option  Trigger  Window.  The
applicable Sublessors shall be obligated to sell, and TowerCo shall be obligated
to buy,  all such Sites at a closing to be  effective  as of the  relevant  Site
Expiration Outside Date. SBC shall use commercially reasonable efforts to obtain
(i) all consents to TowerCo's  purchase of Leased Sites pursuant to this Section
<PAGE>   62
                                                                              60

35 that may be required by the Ground Leases encumbering such Sites and a waiver
of any right of first  refusal or similar  provision  in any Ground Lease giving
the Ground Lessor the right to acquire the Site or Tower in question as a result
of the exercise of such right and (ii) all  approvals,  waivers or releases from
any contractual obligation under any colocation agreements, master agreements or
other  contracts  or  agreements  in existence on the date hereof which would be
violated by the transfer of any Site to TowerCo  pursuant to this Section 35. In
the event that SBC cannot  obtain  such  consents  or waivers on or prior to the
closing date determined  pursuant to Section 35(b), then SBC shall, at TowerCo's
option,  enter into  alternative  arrangements  mutually  acceptable  to SBC and
TowerCo which do not violate the terms of the applicable  Ground Leases or other
agreements  and which  provide  TowerCo with rights and benefits  comparable  to
those afforded by an assignment.  Except as provided in this Section 35, TowerCo
shall have no right or option to purchase the Sites subject to this Sublease.

(b) Payment of the Purchase  Price.  TowerCo  shall pay to SBC (as agent for the
applicable  Sublessors)  the Option  Purchase  Price Amounts and any  additional
amounts  determined  pursuant to Section 3(i) hereof for the applicable Sites in
cash or immediately  available funds on or prior to the closing of such sale. At
the  closing of such sale,  SBC shall  transfer or cause to be  transferred  the
purchased Sites, at TowerCo's expense,  to TowerCo and the Term as to such Sites
shall end.  Risk of loss for the Sites  purchased  pursuant  to Section 35 shall
pass from the  applicable  Sublessor(s)  to TowerCo upon payment of the purchase
price therefor. This Sublease shall remain in full force and effect with respect
to Sites  subject to TowerCo's  binding  election  under Section 35(a) until the
applicable Site Expiration Outside Date.

(c)  Transfer  by SBC.  Any  transfer  of Sites by SBC or any SBC  Affiliate  to
TowerCo pursuant to this Section 35 shall include:

     (i)  an  assignment  of  Sublessor's  interest in any Ground Lease for such
          Site, a transfer of fee simple title to the Land for any Site which is
          an Owned Site, a transfer of  Sublessor's  interest in the  applicable
          Tower and related assets (other than SBC Improvements, including SBC's
          and all SBC Affiliates'  current or future  Communications  Equipment)
          and all appurtenances thereto; provided that for so long as the Ground
          Lease, as amended,  modified,  or extended, is still in effect, SBC or
          any SBC Affiliate  shall be entitled to continue to lease the Reserved
          Space on each such Site from  TowerCo for  successive  1 year terms at
          rental  rate equal to the  lesser of the then  current  market  rental
          rates for  comparable  locations as mutually  agreed to by SBC or such
          SBC Affiliate and TowerCo on an annual basis prior to the commencement
          of each  lease  year  or the  Leaseback  Charge  then  being  charged,
          provided  that the  Leaseback  Charge shall  thereafter  be subject to
          increase on an annual basis at the beginning of each 1-year term in an
          amount equal to the CPI Change; provided,  further however, if TowerCo
          and SBC or the applicable SBC Affiliate fail to agree on a rental rate
          for one or more of the Sites, such rental rate shall be determined for
          each applicable Site by Ernst & Young or another nationally recognized
          independent   accounting  firm  mutually  acceptable  to  SBC  or  the
          applicable SBC Affiliate and TowerCo. The cost of the determination of
          the rental rate shall be shared equally by SBC and TowerCo. SBC or the
          applicable  SBC  Affiliate  shall have the right to elect to terminate
          any such lease with  respect  to a Site as of the  expiration  of each
          annual  term by giving  no less than  sixty  (60) days  prior  written
          notice of such termination to TowerCo;
<PAGE>   63
                                                                              61

(ii)     to the extent legally transferable,  all rights of SBC or any Sublessor
         under or pursuant to warranties, representations and guarantees made by
         suppliers or  manufacturers in connection with such Site, but excluding
         any rights to receive  amounts under such  warranties,  representations
         and guarantees  representing  reimbursements for items paid by SBC or a
         Sublessor; and

(iii)    to the  extent  legally  transferable,  all known and  unknown  rights,
         claims,  credits, causes of action, or rights to commence any causes of
         action or rights of setoff of SBC or a Sublessor  against third parties
         relating  to such  Site  arising  on or  after  the  date of  transfer,
         including   unliquidated  rights  under   manufacturers'  and  vendors'
         warranties,  but excluding all amounts representing  reimbursements for
         items paid by SBC or a Sublessor.

(d)  Evidence  of  Transfer.   The   Sublessor  and  TowerCo  shall  enter  into
assignments,  deeds (with  warranties of title as to Sublessor's  actions only),
bills of sale  and  such  other  documents  and  instruments  as the  other  may
reasonably request to evidence any transfer of such Sites.

(e) No Warranties.  Any transfer of a Site by a Sublessor or TowerCo pursuant to
this  Sublease  shall be "AS IS" and without any warranty  whatsoever  by SBC or
TowerCo,  except  that in any  transfer  of a Site  by a  Sublessor  to  TowerCo
pursuant to this  Sublease,  Sublessor  shall warrant that it has not previously
transferred title to such Site that is so transferred and that each such Site is
free of Liens created by or through SBC or any SBC Affiliate.

(f)  Failure  to  Transfer  by SBC.  In the  event  SBC  fails to  transfer,  in
accordance  with  the  provision  of  this  Section  35 or to  make  alternative
arrangements, in accordance with the provisions of Section 35(a), one or more of
the Sites for which TowerCo has properly exercised its option under this Section
35 by giving to SBC written notice of its election to purchase such Sites within
the Option Trigger Window and provided that TowerCo has complied with all of its
other  obligations  under this Section 35, this Sublease shall  automatically be
extended  (such  extension  to be at  TowerCo's  expense)  (i) with respect to a
Leased Site, until the sooner to occur of (A) the date which is ninety-nine (99)
years from the relevant Site Expiration  Outside Date(s) or (B) one day prior to
the  expiration  of the  relevant  Ground  Lease (as the same may be  renewed or
extended pursuant to Section 3 hereof),  and (ii) with respect to an Owned Site,
for a period of ninety-nine  (99) years from the Site  Expiration  Outside Date,
upon receipt by SBC of the applicable Option Purchase Price Amount(s); provided,
however,  that such  extension  shall not  preclude any other remedy or remedies
provided  in this  Sublease  or  provided  for or allowed by law or in equity by
reason  of such  failure.  In the  event  of such  extension  of the term of the
Sublease  as  provided  herein,  SBC shall have the right to lease the  Reserved
Space at the applicable  Sites pursuant to the terms of clause  35(c)(i)  above.
Such extension shall be conditioned on TowerCo's acquisition of (and the payment
of the Option  Purchase Price Amount(s) for) the balance of Sites which were the
subject of the option closing in question and the receipt of any consent, waiver
or release  required under the applicable  Ground Leases or other  agreements or
contracts in existence on the date hereof (which  consents,  waivers or releases
the parties shall use commercially reasonable efforts to obtain).
<PAGE>   64
                                                                              62

SECTION 36.       Net Lease.

         This  Sublease   (along  with  the   corresponding   Site   Designation
Supplement)  is a net lease  and,  except as  otherwise  expressly  provided  in
Sections  13, 19 and 30  hereof,  shall not  terminate,  nor  shall  TowerCo  be
entitled to any abatement, reduction, setoff, counterclaim, defense or deduction
with  respect to any Rent or other sum payable  hereunder.  Except as  otherwise
expressly  provided in Sections 13, 19 and 30 hereof,  the obligation of TowerCo
under this Sublease or any Site Designation  Supplement shall not be affected by
reason of: (a) any damage to or  destruction  of any Site or any part thereof by
any  cause  whatsoever;  (b)  any  condemnation  of  any of the  Site;  (c)  any
prohibition, limitation, restriction or prevention of TowerCo's use or enjoyment
of a Site by any person;  (d) any matter affecting title to any Site or any part
thereof;  (e) any loss of  possession  by TowerCo of a Site or any  portion,  by
reason of title paramount or otherwise;  (f) the invalidity or  unenforceability
of any provision hereof or the impossibility or illegality of performance by SBC
or  TowerCo  or both;  (g) any action of any  federal,  state,  local or foreign
Governmental Authority; or (h) any other cause or occurrence whatsoever, whether
similar or dissimilar to the foregoing.  The parties intend that the obligations
of TowerCo  hereunder shall continue  unaffected  unless such obligations  shall
have been  modified  or  terminated  pursuant  to an express  provision  of this
Sublease.

SECTION 37.       Compliance with Specific FCC Regulations.

(a) TowerCo  understands and  acknowledges  that Space Subtenants are engaged in
the  business  of  operating  communications   equipment,   including,   without
limitation,  Communications Equipment at each Site. The Communications Equipment
is  subject  to  the  regulations  of  the  FCC,  including  without  limitation
regulations regarding exposure by workers and members of the public to the radio
frequency  emissions  generated  by  SBC's  Communications  Equipment.   TowerCo
acknowledges that such regulations  prescribe the permissible exposure levels to
emissions  from the  Communications  Equipment  which  can  generally  be met by
maintaining  safe  distances  from such  Communications  Equipment.  In order to
comply  with  such  regulations,  TowerCo  shall  install,  or cause  the  Space
Subtenants  to  install,  at its or their  expense,  such  marking,  signage  or
barriers to restrict  access to any  Subleased  Property of each Site as TowerCo
deems necessary in order to comply with the applicable FCC regulations.  TowerCo
further  agrees to post,  or to cause the Space  Subtenants  to post,  prominent
signage at all points of entry to the Subleased Property of each Site containing
instructions  as to any  potential  risk of exposure and methods for  minimizing
such risk.  TowerCo  shall  cooperate  in good faith  with SBC to  minimize  any
confusion or unnecessary  duplication that could result in similar signage being
posted with respect to any of SBC's  transmission  equipment at or near any Site
in respect of any Reserved Space on such Site.

(b) TowerCo further agrees to alert all personnel  working at or near each Site,
including  TowerCo's  maintenance  and  inspection  personnel,  to  heed  all of
TowerCo's  or Space  Subtenant's  signage or  restrictions  with  respect to the
Subleased  Property of a Site,  to maintain  the  prescribed  distance  from the
Communications Equipment, and to otherwise follow the posted instructions.
<PAGE>   65
                                                                              63

TowerCo further agrees to alert each Space Subtenant in advance of any repair or
maintenance  work to be  performance  on any Site which  would  require  work in
closer  proximity to the Subleased  Property  than  prescribed by the signage or
restrictions.

(c) TowerCo  agrees to cooperate  with each Space  Subtenant on a  going-forward
basis  with  respect to each Site in order to insure  that such Space  Subtenant
complies with the applicable FCC regulations.

(d)  SBC   acknowledges   and  agrees   that  its  (and  any  SBC   Affiliates')
Communications  Equipment at each Site is subject to the regulations of the FCC,
including  without  limitation  regulations  regarding  exposure  by workers and
members of the public to the radio frequency  emissions  generated by SBC's (and
any SBC  Affiliates')  Communications  Equipment.  SBC  acknowledges  that  such
regulations  prescribe the  permissible  exposure  levels to emissions  from its
Communications  Equipment  which  can  generally  be  met  by  maintaining  safe
distances from such Communications  Equipment. SBC shall cooperate in good faith
with TowerCo to minimize any  confusion or  unnecessary  duplication  that could
result in similar  signage  being  posted with  respect to any of SBC's (and its
Affiliates')  transmission  equipment  at or near  any  Site in  respect  of any
Reserved Space on such Site.

(e) SBC  further  agrees to alert all  personnel  working  at or near each Site,
including SBC's maintenance and inspection personnel, to maintain the prescribed
distance from the Communications  Equipment,  and to otherwise follow the posted
instructions of TowerCo.

SECTION 38.       Guaranty.

(a) TowerCo Parent's Guaranty. TowerCo Parent unconditionally guarantees to SBC,
the Sublessors, the SBC Affiliates,  and each SBC Indemnitee (collectively,  the
"beneficiaries",  individually a "beneficiary")  the full and timely payment and
performance  and  observance  of all of the  terms,  provisions,  covenants  and
obligations of TowerCo under this Sublease and each Site Designation  Supplement
(the "TowerCo  Obligations").  TowerCo Parent agrees that if TowerCo defaults at
any time during the Term of this Sublease or any Site Designation  Supplement in
the  performance  of  any of  the  TowerCo  Obligations,  TowerCo  Parent  shall
faithfully  perform and fulfill  all  TowerCo  Obligations  and shall pay to the
applicable  beneficiary all attorneys'  fees,  court costs,  and other expenses,
costs and disbursements incurred by the applicable beneficiary on account of any
default by TowerCo and on account of the enforcement of this guaranty.

         If  TowerCo  defaults  under  this  Sublease  or any  Site  Designation
Supplement,  and the applicable  beneficiary elects to enforce the provisions of
this Section 38, the applicable  beneficiary  shall promptly give TowerCo Parent
written  notice  thereof,  which  notice  shall  constitute  an  exercise of the
applicable  beneficiary's rights against TowerCo Parent pursuant to this Section
38. Following the receipt of such notice by TowerCo Parent, TowerCo Parent shall
have the same period of time as is afforded  to TowerCo  under this  Sublease or
the applicable  Site  Designation  Supplement to cure such default,  but no such
cure period shall diminish the  obligations of TowerCo Parent under this Section
38.
<PAGE>   66
                                                                              64

         This guaranty  obligation of TowerCo Parent shall be enforceable by the
applicable beneficiary in an action against TowerCo Parent without the necessity
of any suit, action, or proceedings by the applicable beneficiary of any kind or
nature  whatsoever  against  TowerCo,  without  the  necessity  of any notice to
TowerCo  Parent of  TowerCo's  default  or breach  under  this  Sublease  or the
applicable Site Designation  Supplement,  and without the necessity of any other
notice or demand to TowerCo  Parent to which TowerCo  Parent might  otherwise be
entitled,  all of which notices TowerCo Parent hereby expressly waives.  TowerCo
Parent hereby agrees that the validity of this guaranty and the  obligations  of
TowerCo Parent  hereunder  shall not be  terminated,  affected,  diminished,  or
impaired by reason of the  assertion or the failure to assert by the  applicable
beneficiary  against  TowerCo  any of the  rights or  remedies  reserved  to the
applicable  beneficiary  pursuant  to the  provisions  of this  Sublease  or the
applicable  Site  Designation  Supplement or any other remedy or right which the
applicable beneficiary may have at law or in equity or otherwise.

         TowerCo Parent  covenants and agrees that this guaranty is an absolute,
unconditional,  irrevocable  and continuing  guaranty.  The liability of TowerCo
Parent hereunder shall not be affected, modified, or diminished by reason of any
assignment,  renewal,  modification  or extension  of this  Sublease or any Site
Designation  Supplement or any modification or waiver of or change in any of the
covenants  and terms of this  Sublease  or any Site  Designation  Supplement  by
agreement of a beneficiary and TowerCo,  or by any unilateral action of either a
beneficiary  or  TowerCo,  or by an  extension  of time that may be granted by a
beneficiary to TowerCo or any indulgence of any kind granted to TowerCo,  or any
dealings or transactions occurring between a beneficiary and TowerCo, including,
without  limitation,  any  adjustment,   compromise,   settlement,   accord  and
satisfaction,  or  release,  or  any  bankruptcy,  insolvency,   reorganization,
arrangements,   assignment  for  the  benefit  of  creditors,  receivership,  or
trusteeship  affecting  TowerCo.  TowerCo Parent does hereby expressly waive any
suretyship  defense it may have by virtue of any  statute,  law, or ordinance of
any state or other governmental authority.

         All of the  beneficiaries'  rights and remedies under this guaranty are
intended to be distinct,  separate,  and cumulative and no such right and remedy
herein is intended to be the exclusion of or a waiver of any other.

         TowerCo  Parent  hereby  waives  presentment,  demand for  performance,
notice of nonperformance,  protest,  notice of protest,  notice of dishonor, and
notice of acceptance. TowerCo Parent further waives any right to require that an
action be brought  against TowerCo or any other person or to require that resort
be had by a beneficiary to any security held by such beneficiary.

         (b) Wireless Guarantor's Guaranty.  Wireless Guarantor  unconditionally
guarantees   to  TowerCo  and  each  TowerCo   Indemnitee   (collectively,   the
"beneficiaries",  individually a "beneficiary")  the full and timely payment and
performance  and  observance  of all of the  terms,  provisions,  covenants  and
obligations  of SBC and  each  Sublessor  under  this  Sublease  and  each  Site
Designation  Supplement (the "SBC Obligations").  Wireless Guarantor agrees that
if SBC or a Sublessor  defaults at any time during the Term of this  Sublease or
any  Site  Designation   Supplement  in  the  performance  of  any  of  the  SBC
Obligations,  Wireless  Guarantor shall  faithfully  perform and fulfill all SBC
Obligations  and shall pay to the applicable  beneficiary  all attorneys'  fees,
<PAGE>   67
                                                                              65

court  costs,  and other  expenses,  costs  and  disbursements  incurred  by the
applicable  beneficiary  on account of any default by SBC or a Sublessor  and on
account of the enforcement of this guaranty.

         If SBC or the applicable  Sublessor defaults under this Sublease or any
Site Designation  Supplement,  and the applicable  beneficiary elects to enforce
the  provisions of this Section 38, the  applicable  beneficiary  shall promptly
give Wireless Guarantor written notice thereof, which notice shall constitute an
exercise of the  applicable  beneficiary's  rights  against  Wireless  Guarantor
pursuant to this  Section 38.  Following  the receipt of such notice by Wireless
Guarantor,  Wireless Guarantor shall have the same period of time as is afforded
to SBC or the applicable  Sublessor  under this Sublease or the applicable  Site
Designation  Supplement  to cure such  default,  but no such cure  period  shall
diminish the SBC Obligations of Wireless Guarantor under this Section 38.

         This guaranty  obligation of Wireless Guarantor shall be enforceable by
the applicable  beneficiary in an action against Wireless  Guarantor without the
necessity of any suit,  action, or proceedings by the applicable  beneficiary of
any kind or nature whatsoever against SBC or the applicable  Sublessor,  without
the  necessity  of any notice to Wireless  Guarantor  of such  default or breach
under this Sublease or the applicable Site Designation  Supplement,  and without
the  necessity  of any other  notice or demand to  Wireless  Guarantor  to which
Wireless  Guarantor might otherwise be entitled,  all of which notices  Wireless
Guarantor hereby  expressly  waives.  Wireless  Guarantor hereby agrees that the
validity of this guaranty and the  obligations of Wireless  Guarantor  hereunder
shall not be  terminated,  affected,  diminished,  or  impaired by reason of the
assertion or the failure to assert by the applicable  beneficiary against SBC or
the  applicable  Sublessor  any  of  the  rights  or  remedies  reserved  to the
applicable  beneficiary  pursuant  to the  provisions  of this  Sublease  or the
applicable  Site  Designation  Supplement or any other remedy or right which the
applicable beneficiary may have at law or in equity or otherwise.

         Wireless  Guarantor  covenants  and  agrees  that this  guaranty  is an
absolute,  unconditional,  irrevocable and continuing guaranty. The liability of
Wireless Guarantor hereunder shall not be affected,  modified,  or diminished by
reason of any assignment, renewal, modification or extension of this Sublease or
any Site  Designation  Supplement or any  modification or waiver of or change in
any of the  covenants  and  terms  of  this  Sublease  or any  Site  Designation
Supplement by agreement of a  beneficiary  and SBC or any  Sublessor,  or by any
unilateral  action of either a  beneficiary  or SBC or any  Sublessor,  or by an
extension of time that may be granted by a  beneficiary  to SBC or any Sublessor
or any indulgence of any kind granted to SBC or any  Sublessor,  or any dealings
or  transactions  occurring  between  a  beneficiary  and SBC or any  Sublessor,
including, without limitation, any adjustment,  compromise,  settlement,  accord
and satisfaction,  or release,  or any bankruptcy,  insolvency,  reorganization,
arrangements,   assignment  for  the  benefit  of  creditors,  receivership,  or
trusteeship  affecting  SBC or any  Sublessor.  Wireless  Guarantor  does hereby
expressly  waive any  suretyship  defense it may have by virtue of any  statute,
law, or ordinance of any state or other governmental authority.

         All of the  beneficiaries'  rights and remedies under this guaranty are
intended to be distinct,  separate,  and cumulative and no such right and remedy
herein is intended to be the exclusion of or a waiver of any other.
<PAGE>   68
                                                                              66

         Wireless Guarantor hereby waives  presentment,  demand for performance,
notice of nonperformance,  protest,  notice of protest,  notice of dishonor, and
notice of  acceptance.  Wireless  Guarantor  further waives any right to require
that an action be brought  against  SBC or any other  person or to require  that
resort be had by a beneficiary to any security held by such beneficiary.

SECTION 39.       Tax Indemnities.

(a)      Income Tax Indemnity.

     (1) Tax Assumptions.  In entering into this Sublease and related documents,
the SBC Group has made the following  assumptions regarding the characterization
of the transactions  contemplated hereunder for federal income tax purposes (the
"Tax Assumptions"):

     (i)  for federal  income tax  purposes,  the Sublease  will be treated as a
          "true  lease"  with  respect  to all of the  Subleased  Property,  the
          members  of the SBC Group  will be  treated,  directly  or  indirectly
          through one or more entities that are  classified as  partnerships  or
          disregarded  entities for federal  income tax purposes,  as the owners
          and Sublessors of the Subleased Property,  and TowerCo will be treated
          as the lessee of the Subleased Property;

     (ii) following  the  execution  of this  Sublease,  the SBC  Group  will be
          entitled  to  deduct,   pursuant  to  Section   168(b)  of  the  Code,
          depreciation  deductions with respect to the adjusted tax basis in the
          Subleased Property using the same depreciation  method(s) as in effect
          immediately   before  the   execution  of  this   Sublease   ("Federal
          Depreciation Deductions");

     (iii)prepaid Rent will be  characterized as a loan under section 467 of the
          Code and Treasury Regulations issued thereunder and the SBC Group will
          be entitled to deduct interest attributable thereto;

     (iv) the only amounts that any SBC Group Member will be required to include
          in gross income with respect to the transactions  contemplated by this
          Sublease  and  related  documents  will be (A) Rent as it  accrues  in
          accordance  with the terms of this  Sublease  and the  application  of
          Section 467 of the Code and Treasury  Regulations  issued  thereunder;
          (B) any indemnity  (including any gross up) pursuant to this Sublease;
          (C) any amounts paid or otherwise  recognized  pursuant to a voluntary
          sale or other  disposition  by any SBC Group Member (other than a sale
          or  disposition  attributable  to a  default  by  TowerCo  and/or  the
          exercise of remedies by SBC or any SBC Affiliate  under this Sublease)
          of any Subleased Property; and (D) proceeds upon TowerCo's exercise of
          the purchase option pursuant to Section 35 of this Sublease; and

     (v)  the  combined   effective  federal  and  net  state  income  tax  rate
          applicable  to each SBC Group Member will be 39 percent (the  "Assumed
          Rate"),  comprised  of 35 percent for the assumed  federal  rate and 4
          percent  (which is net of federal income tax benefits) for the assumed
          state rate.
<PAGE>   69
                                                                              67

(2)      TowerCo's  Representations  and Covenants.  TowerCo  hereby  represents
and covenants to each SBC Group Member as follows:

     (i)  TowerCo,  any  Affiliate  of TowerCo,  any  assignee or  sublessee  of
          TowerCo,  and any  user  (other  than  SBC or its  Affiliates)  of any
          portion  of  the  Subleased   Property  will  not  claim  depreciation
          deductions as the owner of any of the  Subleased  Property for federal
          income tax purposes  during the Term (and  thereafter  unless  TowerCo
          purchases such property  pursuant to Section 35 hereof),  with respect
          to such Subleased Property or portion thereof,  except with respect to
          Alterations financed by TowerCo or such assignee,  sublessee, or other
          user, nor will they take any other action in connection  with filing a
          Tax return or otherwise which would be inconsistent with the treatment
          of the  SBC  Group  Members  as the  direct  or  indirect  owners  and
          Sublessors of the Subleased Property for federal income tax purposes;

     (ii) none  of  the  Subleased  Property  will  constitute  "tax-exempt  use
          property" as defined in Section  168(h) of the Code as a result of the
          status of TowerCo or any assignee,  sublessee, or user (other than SBC
          or its Affiliates) of the Subleased Property;

     (iii)to the best of TowerCo's knowledge,  on the Site Commencement Date, no
          Alterations to any of the Subleased Property will be required in order
          to render any of the Subleased  Property complete for its intended use
          by  TowerCo  except  for  ancillary  Severable  Alterations  that  are
          customarily  selected and furnished by lessees of property  similar in
          nature to the Subleased Property;

     (iv) Except to the extent that TowerCo may make Non-Conforming  Alterations
          pursuant  to Section  3(i)  hereof,  TowerCo  has no  current  plan or
          intention  of making any  Alteration  or repair with respect to any of
          the  Subleased  Property  that  would  not  be  treated  as  severable
          improvements or permitted nonseverable improvements within the meaning
          of Revenue  Procedure  75-21,  1975-1 C.B.  715, or Revenue  Procedure
          79-48,  1979-2 C.B.  599; (v) TowerCo has no current plan or intention
          of  making  any  Alteration  or  repair  with  respect  to  any of the
          Subleased  Property  the value of which as of the end of the Term with
          respect to such  Subleased  Property  would compel TowerCo to exercise
          any of the purchase options under Section 35 of this Sublease;

     (vi) TowerCo is not  obligated  to  exercise  any of the  purchase  options
          provided in Section 35 of this Sublease, it has not decided whether it
          will  exercise any of the purchase  options  provided in Section 35 of
          this  Sublease,  and it has no  plans  to  enter  into or  incur  such
          obligation or to make such decision in the immediate future;

     (vii)TowerCo  has no reason to believe  that the fair  market  value of any
          Subleased  Property,  determined  at the  end of the  applicable  Term
          (taking into account  inflation or deflation),  is equal to or greater
          than the Option Purchase Price Amount of such Subleased Property; and
<PAGE>   70
                                                                              68

     (viii)  TowerCo  believes  that  the Rent  with  respect  to any  Subleased
          Property is no greater  than the fair rental  value of such  Subleased
          Property throughout the Term.

(3)      Indemnity for Tax Losses.

     (ix) If, as a result of

     (A)  the inaccuracy of any representation of TowerCo,  or the breach of any
          covenant of TowerCo, set forth in Section 39(a)(2) hereof;

     (B)  any act of TowerCo,  or any  assignee or  sublessee  of TowerCo or any
          user of the  Subleased  Property  (other  than SBC or its  Affiliates)
          during the Term,  other than any act  required  under the  Transaction
          Documents;

     (C)  the failure by TowerCo to perform any act  required of it under any of
          the Transaction Documents;

     (D)  the failure by TowerCo to perform any act reasonably  requested by any
          SBC Group Member provided that (1) such act is not  inconsistent  with
          the   obligations  of  TowerCo  and  other   requirements   under  the
          Transaction  Documents,  (2) such act does not have any adverse effect
          on TowerCo,  and (3) such SBC Group  Member or SBC agrees to reimburse
          TowerCo  for  all  reasonable   costs  incurred  in  connection   with
          performing such act;

     (E)  any  disposition of Subleased  Property  attributable  to a default by
          TowerCo and/or the exercise of remedies under this Sublease; or

     (F)  the bankruptcy of TowerCo,

any SBC Group Member (each a "Tax  Indemnitee")  shall not claim on the relevant
income tax return  (based upon a written  opinion from  independent  tax counsel
that there is no reasonable basis that is consistent with the standards provided
for in ABA Formal  Opinion  85-352 as in effect on the date hereof for claiming)
all or any portion of the Federal  Income Tax Benefits,  shall lose the right to
claim all or any portion of the Federal Income Tax Benefits, shall suffer a loss
of,  disallowance  of, or delay in  obtaining  all or any portion of the Federal
Income Tax Benefits, or shall be required to recapture all or any portion of the
Federal  Income Tax Benefits,  or any Tax  Indemnitee  shall suffer an Inclusion
(any such event being  referred to as a "Tax Loss"),  then,  within  thirty (30)
days after receipt of a written  demand from or on behalf of the Tax  Indemnitee
describing in reasonable  detail the Tax Loss and the  computation of the amount
payable (a "Tax Indemnity Notice"),  TowerCo shall pay to such Tax Indemnitee as
an indemnity the amount specified in the Tax Indemnity Notice.  Subject to other
adjustments required by this Section  39(a)(3)(i),  such indemnity payment shall
be calculated in the Tax Indemnity  Notice to equal, on an After-Tax  Basis, the
sum of (y) the amounts of any additional  federal and state income taxes payable
by such Tax  Indemnitee  for the taxable year  calculated at the Assumed Rate as
the result of such Tax Loss and any  interest  thereon  (calculated  to the date
such payment is made using the actual  interest rates for  underpayments  of tax
applicable  to the relevant  periods),  plus (z) the amount of any penalties and
additions to tax actually  payable as a result of such Tax Loss and attributable
thereto.  At the option of such Tax Indemnitee,  the indemnity  payment shall be
determined  on a  periodic,  or "pay as you go," basis,  with each such  payment
reduced for any reduction in Taxes also calculated at the Assumed Rate resulting
from any Tax benefits  realized by such Tax  Indemnitee as a result of the event
<PAGE>   71
                                                                              69

giving rise to the indemnity payment.  Alternatively,  at the option of such Tax
Indemnitee,  the indemnity  payment shall be a net lump-sum amount,  taking into
account  all past and  anticipated  future  Tax  Losses  and Tax  savings at the
Assumed Rate, and using a discount rate equal to the Applicable Federal Rate (as
defined in Code section  1274(d)(1)  then in effect) to present value future Tax
Losses and Tax savings.  Any  indemnity  payment  made  pursuant to this Section
39(a)(3)(i)  shall be made on an  "After-Tax  Basis"  which  means that any such
payment  shall also include a  "gross-up"  for any federal or state income Taxes
(determined at the highest marginal  applicable  federal and state rates then in
effect) payable by such Tax Indemnitee with respect to the receipt or accrual of
such  indemnity  payment,  including such  gross-up.  Notwithstanding  any other
provision of this Section  39(a)(3)(i)  to the  contrary,  TowerCo  shall not be
required to make any payment under this Section 39(a)(3)(i) earlier than, (a) in
the case of a Tax Loss that is not being  contested  pursuant  to Section  39(d)
hereof,  the date such Tax Indemnitee (or the common parent of the  consolidated
group in which it is a member, as the case may be) files the applicable  federal
income Tax  return,  estimated  or final as the case may be,  which  would first
properly reflect the additional federal income Tax that would be due as a result
of the Tax  Loss  and (b) in the  case of a Tax  Loss  that is  being  contested
pursuant  to Section  39(d)  hereof,  thirty (30) days after the date on which a
Final Determination is made (or as otherwise provided in Section 39(d)).

     (ii) Verification of Calculations.  TowerCo may timely request that any Tax
          Indemnity  Notice be verified  by Ernst & Young or another  nationally
          recognized   independent  accounting  firm  selected  by  TowerCo  and
          reasonably acceptable to such Tax Indemnitee.  Such verification shall
          be at TowerCo's  expense unless such  accounting  firm determines that
          the amount  payable by TowerCo is more than ten percent  less than the
          amount  shown on the Tax  Indemnity  Notice,  in which  event  the Tax
          Indemnitee  shall pay such costs. In order to enable such  independent
          accountants to verify such amounts,  the Tax Indemnitee  shall provide
          to such independent accountants (for their confidential use and not to
          be  disclosed  to  TowerCo  or  any  other  person)  all   information
          reasonably necessary for such verification.

(4)  Exceptions.  Notwithstanding  any  provision of this  Section  39(a) to the
contrary,  TowerCo  shall  not be  required  to  make  any  payment  to any  Tax
Indemnitee  in  respect  of any Tax  Loss to the  extent  that any such Tax Loss
occurs as a result of one or more of the following events:

     (i)  Except to the extent of any inaccuracy of a  representation  or breach
          of covenant of TowerCo in Section 39(a)(2) hereof,  any act of TowerCo
          or any assignee or  sublessee of TowerCo or any user of the  Subleased
          Property  (other  than  SBC or its  Affiliates)  other  than  any  act
          required  under any of the  Transaction  Documents,  or any failure by
          TowerCo to perform any act required of it under any of the Transaction
          Documents or any act reasonably requested by any SBC Group Member with
          respect to which the three conditions in Section  39(a)(3)(i)(D)  have
          been  satisfied,  a  determination  that the  Sublease  is not a "true
          lease" for federal  income tax purposes or such Tax  Indemnitee is not
          the owner or Sublessor of the applicable Subleased Property;
<PAGE>   72
                                                                              70

     (ii) Except to the extent caused by any inaccuracy of a  representation  or
          breach of covenant of TowerCo in Section 39(a)(2)  hereof,  any act of
          TowerCo or any  assignee  or  sublessee  of TowerCo or any user of the
          Subleased  Property (other than SBC or its Affiliates)  other than any
          act required under any of the Transaction Documents, or any failure by
          TowerCo to perform any act required of it under any of the Transaction
          Documents or any act reasonably requested by any SBC Group Member with
          respect to which the three conditions in Section  39(a)(3)(i)(D)  have
          been satisfied,  the voluntary sale,  assignment,  transfer,  or other
          disposition or the involuntary sale,  assignment,  transfer,  or other
          disposition  attributable to the bankruptcy,  insolvency or the breach
          of any covenant or obligation of the Tax  Indemnitee  set forth in the
          Transaction  Documents  of or by any such Tax  Indemnitee,  in  either
          case, of any of the Subleased  Property or portion thereof by any such
          Tax Indemnitee other than a sale, assignment, transfer, or disposition
          (A)  contemplated  by the  Transaction  Documents  or  otherwise;  (B)
          otherwise  resulting  from the exercise by any SBC Group Member of its
          rights  or  performance  of  its  obligations  under  the  Transaction
          Documents; or (C) attributable to a default by TowerCo and/or exercise
          of remedies under this Sublease;

     (iii) the gross negligence or willful misconduct of such Tax Indemnitee;

     (iv) penalties,  interest,  or  additions  to Tax to the extent  based upon
          issues unrelated to the transactions  contemplated by the Sublease and
          related documents;

     (v)  the  inclusion in income by any SBC Group  Member on its U.S.  federal
          income tax return of any amount  attributable  to an Inclusion  unless
          (x) such  Inclusion is supported by a written  opinion of  independent
          tax  counsel  that there is no  reasonable  possibility  of success in
          taking the position that the amount is not  includable  in income,  or
          (y) such  Inclusion  shall be due to the failure of TowerCo  timely to
          provide  Tax  Indemnitee  with  information  reasonably  available  to
          TowerCo that is timely  requested in writing by the Tax Indemnitee and
          necessary for the Tax  Indemnitee to exclude such amounts from income;
          and

     (vi) any failure of the Tax  Indemnitee  to have taken all the actions,  if
          any,  required of it by Section  39(d)  hereof to contest the Loss and
          such failure materially prejudices the ability to contest, and TowerCo
          has a  reasonable  basis  for  such  contest  (other  than  a  failure
          attributable  in whole or part to the failure of TowerCo to follow the
          procedures set forth in Section 39(d) hereof).

(b)      General Tax Indemnity.

(1)  Except  as  provided  in  Section  39(b)(2),  TowerCo  agrees to pay and to
indemnify,  protect, defend, save, and keep harmless each SBC Group Member on an
After-Tax Basis, from and against any and all taxes, impositions,  fees, levies,
assessments, duties, withholdings,  governmental claims, or other charges of any
nature whatsoever  (together with any related  interest,  fines,  penalties,  or
additions to tax), including without limitation,  rental,  income,  withholding,
<PAGE>   73
                                                                              71

sales, use,  transfer,  leasing,  personal or real property,  excise,  receipts,
franchise,  value-added,  stamp, filing,  recording,  documentation,  or license
taxes,  however  imposed  or  asserted,  by any  United  States  state  or local
government  or taxing  authority  (all the foregoing  being herein  collectively
called  "Taxes" or,  separately a "Tax",  upon or with respect to (A) any of the
Subleased  Property,  any  portion  thereof,  or any  interest  therein  (B) the
acquisition,   purchase,  sale,  financing,   leasing,  subleasing,   ownership,
maintenance, repair, redelivery,  alteration, insuring, control, use, operation,
delivery,  possession,  repossession,  location, storage,  refinancing,  refund,
transfer  of title,  registration,  reregistration,  transfer  of  registration,
return,  or other  disposition  thereof of any of the Subleased  Property or any
portion thereof,  or interest  therein,  (C) the rental payments,  receipts,  or
earnings  arising  from the  Subleased  Property,  any portion  thereof,  or any
interest therein,  or payable pursuant to the Sublease,  or any other payment or
right  to  receive  payment  pursuant  to  any  related  document,  or  (D)  any
Alteration,  removal,  substitution,  maintenance,  or  repair  of  any  of  the
Subleased Property.

     (i)  Exclusions  from  General Tax  Indemnity.  The  provisions  of Section
          39(b)(1) shall not apply to, and TowerCo shall have no liability under
          Section 39(b)(1) with respect to:

     (ii) Taxes on any SBC Group  Member  (other than such Taxes that are sales,
          use, rental, property,  stamp, document filing, license, or ad valorem
          Taxes,  or value  added  Taxes that are in the nature of or in lieu of
          such  Taxes)  imposed on any such  member  that are  franchise  Taxes,
          privilege  Taxes,  doing business Taxes, or Taxes imposed on, based on
          or measured by, gross or net income,  receipts,  capital, or net worth
          of any such  member  which are imposed by any state,  local,  or other
          taxing  authority  within  the  United  States  or by any  foreign  or
          international  taxing  authority that would have been imposed  without
          regard to the execution of this Sublease and related documents and the
          transactions contemplated thereunder;

     (iii)Taxes on any SBC Group Member, including without limitation, sales and
          transfer Taxes,  that result from any transfer by any SBC Group Member
          of  any of the  Subleased  Property  other  than a  sale,  assignment,
          transfer,  or  disposition  (I)  attributable  to a default by TowerCo
          and/or exercise of remedies under this Sublease or related  documents;
          (II) resulting from any maintenance, repair, Alteration, substitution,
          relocation,  or removal  of or any  addition  to any of the  Subleased
          Property or portion thereof or interest therein,  (III) resulting from
          any loss, damage, destruction, theft, taking, casualty,  condemnation,
          confiscation,  expropriation,  or seizure of any Subleased Property or
          portion  thereof  or  interest  therein;  or (IV)  resulting  from any
          subleasing, permitting use thereof, or relinquishing possession of any
          Subleased Property or portion thereof or interest therein;

     (iv) Taxes imposed by any  jurisdiction on any SBC Group Member solely as a
          result  of  its  activities  in  such  jurisdiction  unrelated  to the
          transactions contemplated by the Sublease and related documents;

     (v)  Taxes on any SBC Group Member that result from the willful  misconduct
          or gross negligence of any such member or an Affiliate  thereof or the
          inaccuracy or breach of any representation,  warranty,  or covenant of
          such Tax Indemnitee or an Affiliate thereof under the Transaction
<PAGE>   74
                                                                              72

          Documents   (except  to  the  extent  such  inaccuracy  or  breach  is
          attributed to an inaccuracy or breach of any representation,  warranty
          or  covenant  of  TowerCo  or  an  Affiliate   under  the  Transaction
          Documents);

     (vi) Taxes which are  attributable to any period or circumstance  occurring
          after the expiration or earlier  termination of this Sublease,  except
          to the extent  attributable  to (I) a failure of TowerCo or any of its
          transferees  or sublessees or users of the Subleased  Property  (other
          than SBC or its Affiliates) to fully  discharge its obligations  under
          the Sublease and related  documents,  or (II) Taxes imposed on or with
          respect to any payments  that are due after the  expiration or earlier
          termination of the Sublease and which are  attributable to a period or
          circumstance occurring prior to or simultaneously with such expiration
          or earlier termination;

     (vii)any Tax that is being  contested in accordance  with the provisions of
          Section  39(d)  during the pendency of such  contest,  but only for so
          long as such contest is continuing  in  accordance  with Section 39(d)
          and payment is not otherwise required pursuant to Section 39(d); or

     (viii) Taxes imposed on any SBC Group Member that are United States federal
          or state net income Taxes of any such member.

The provisions of this Section  39(b)(2) shall not apply to any Taxes imposed in
respect of the receipt or accrual of any payment made by TowerCo on an After-Tax
Basis.

(2) Reports. If any report, return,  certification,  or statement is required to
be filed with respect to any Tax that is subject to  indemnification  under this
Section  39(b),  TowerCo  shall  timely  prepare and file the same to the extent
permitted by law (except for (i) any report,  return,  or statement  relating to
any net income Taxes or, (ii) any report,  return, or statement  relating to any
other Taxes described in Section  39(b)(2)(i) or any Taxes in lieu of or enacted
in substitution  for any of the foregoing,  except that, in such cases,  TowerCo
shall timely  provide  information  necessary to file such  report,  return,  or
statement or (iii) any other report, return,  certification,  or statement which
any SBC Group  Member has notified  TowerCo that such member  intends to prepare
and file);  provided  that any such  member  shall have  furnished  TowerCo,  at
TowerCo's  expense,  with such information  reasonably  necessary to prepare and
file such returns as is within such member's control.  TowerCo shall either file
such report, return, certification, or statement and send a copy of such report,
return, certification, or statement to the member, or, where not so permitted to
file, shall notify the member of such requirement  within a reasonable period of
time  prior  to the due  date  for  filing  (without  regard  to any  applicable
extensions)  and prepare and deliver  such  report,  return,  certification,  or
statement to the member. In addition, within a reasonable time prior to the time
such report, return, certification,  or statement is to be filed, TowerCo shall,
to the extent  permitted by law,  cause all billings of such Taxes to be made to
each SBC Group  Member in care of TowerCo,  make  payment  thereof,  and furnish
written  evidence of such payment.  TowerCo shall furnish  promptly upon written
request such data,  records and documents as any SBC Group Member may reasonably
require of TowerCo to enable  such  member to comply  with  requirements  of any
taxing  jurisdiction   arising  out  of  such  member's   participation  in  the
transactions contemplated by this Sublease and related documents.
<PAGE>   75
                                                                              73

(3)  Payments.  Any Tax  indemnified  under  this  Section  39(b)  shall be paid
directly  when due to the  applicable  taxing  authority  if direct  payment  is
permitted,  or shall be reimbursed to the appropriate SBC Group Member on demand
if paid by such member in accordance  herewith.  Except as otherwise provided in
this Section 39(b), all amounts payable to a SBC Group Member hereunder shall be
paid promptly in  immediately  available  funds,  but in no event later than the
later of (i) ten (10)  Business  Days after the date of such  demand or (ii) two
(2) Business Days before the date the Tax to which such amount payable hereunder
relates is due or is to be paid and shall be accompanied by a written  statement
describing  in  reasonable  detail  the Tax and the  computation  of the  amount
payable.  Such written statement shall, at TowerCo's request, as long as payment
is not delayed,  be verified by Ernst & Young, or another nationally  recognized
independent  accounting firm selected by such member. Such verification shall be
at TowerCo's  expense  unless the  accounting  firm  determines  that the amount
payable by TowerCo is more than ten percent  less than the amount  shown on such
written  statement,  in which event,  the  applicable SBC Group Member shall pay
such costs. In the case of a Tax subject to  indemnification  under this Section
39(b) which is properly  subject to a contest in accordance  with Section 39(d),
TowerCo (i) shall be  obligated  to make any  advances  with respect to such Tax
whenever required under Section 39(d) and (ii) shall pay such Tax (in the amount
finally  determined to be owing in such contest) on an After-Tax  Basis prior to
the latest time  permitted by the relevant  taxing  authority for timely payment
after a final determination.

(c) Tax Savings.  If, by reason of any payment made to or for the account of any
Tax  Indemnitee  by  TowerCo  pursuant  to  Section  39(a)  or  39(b),  such Tax
Indemnitee  at any time  realizes a reduction  in any Taxes or receives a refund
which was not taken into account previously in computing such payment by TowerCo
to or for the account of the Tax Indemnitee,  then the Tax Indemnitee  shall pay
to TowerCo an amount  equal to such  actual  reduction  in Taxes or such  refund
(including  interest received),  plus the amount of any additional  reduction in
Taxes  of the  Tax  Indemnitee  attributable  to the  payment  made  by the  Tax
Indemnitee to TowerCo pursuant to this sentence; provided, however, that (A) the
Tax  Indemnitee  shall not be obligated to make such payment with respect to any
net Tax  savings or refund to the extent that the amount of such  payment  would
exceed  the  excess of (x) all prior  indemnity  payments  (excluding  costs and
expenses  incurred with respect to contests) made by TowerCo with respect to the
Tax being  refunded or reduced  pursuant to Section 39(a) or 39(b),  as the case
may be,  over (y) the  amount of all prior  payments  by the Tax  Indemnitee  to
TowerCo  hereunder  with respect to such Tax  provided  that any such excess tax
savings  realized (or deemed realized) by such Tax Indemnitee which are not paid
to TowerCo as a result of this subclause (A) shall be carried forward and reduce
TowerCo's  obligations  to  make  subsequent  payments  to such  Tax  Indemnitee
pursuant  to  Section  39  hereof;  and (B) if any such Tax  savings  or  refund
realized by such the Tax  Indemnitee,  or any tax savings taken into account for
purposes of determining  "After-Tax Basis" shall be lost or otherwise determined
to be  unavailable,  such lost or  otherwise  unavailable  Tax savings or refund
shall be treated as a Tax for which TowerCo must  indemnify  the Tax  Indemnitee
pursuant to Section  39(a) or 39(b),  as the case may be (without  regard to the
exceptions  in Section  39(a)(4) or 39(b) other than the Section  39(a)(4)(iii),
39(a)(4)(iv), or 39(b)(2)(iv)).

(d) Contest  Rights.  In the event that any Tax Indemnitee  receives any written
notice of any potential claim or proposed adjustment against such Tax Indemnitee
that  would  result in a Tax Loss  against  which  TowerCo  may be  required  to
<PAGE>   76
                                                                              74

indemnify  pursuant  to  Section  39(a)  or  39(b)  (a "Tax  Claim"),  such  Tax
Indemnitee  shall  promptly  notify  TowerCo  thereof and provide  TowerCo  with
relevant information  thereto;  provided,  however,  that the failure by the Tax
Indemnitee to provide any such information  shall not be treated as a failure to
comply with this Section  39(d)  unless the failure  materially  prejudices  the
conduct of the contest  hereunder.  TowerCo may  require the Tax  Indemnitee  to
contest  such  Tax  Claim at  TowerCo's  expense  and,  in that  event,  the Tax
Indemnitee  shall  consult  with TowerCo in good faith,  but the Tax  Indemnitee
shall retain ultimate control over such contest. Notwithstanding the immediately
preceding  sentence,  the Tax Indemnitee  shall not be obligated to contest such
Tax Claim  unless (1) prior to taking the first such  required  action,  TowerCo
shall  have  furnished  to the Tax  Indemnitee,  in the case of a  contest  with
respect to federal  income  Taxes,  with an opinion of a nationally  recognized,
independent  tax counsel chosen by TowerCo and reasonably  acceptable to the Tax
Indemnitee,  or, in the case of a contest with  respect to other Taxes,  with an
opinion of a qualified tax counsel chosen by TowerCo and  reasonably  acceptable
to the Tax  Indemnitee,  to the effect that there is a reasonable  basis that is
consistent  with the standards  provided for in ABA Formal  Opinion 85-352 as in
effect (on the date  hereof) for the position to be asserted in  contesting  the
matter in question, (2) no event of default by TowerCo under this Sublease shall
have  occurred and be  continuing,  (3) such contest does not involve a material
risk to the Tax Indemnitee of sale,  forfeiture,  or loss of, or the creation of
any lien  on,  any of the  Subleased  Property  or the  imposition  of  criminal
penalties, (4) TowerCo shall have acknowledged,  in writing, that the contest is
with respect to a liability  that is  indemnifiable  by TowerCo  pursuant to the
terms of this Section 39(d),  (5) if TowerCo  reasonably  requests,  and the Tax
Indemnitee  elects to pursue,  a contest that  requires  payment of the Tax as a
condition to pursuing  the  contest,  TowerCo  shall loan,  on an  interest-free
basis, sufficient funds to the Tax Indemnitee to pay the Tax and any interest or
penalties  due on the  date  of  payment,  and  shall  fully  indemnify  the Tax
Indemnitee for any adverse Tax consequences resulting from such advance. The Tax
Indemnitee  shall  not  make,  accept,  or  enter  into a  settlement  or  other
compromise  with respect to any Taxes  indemnified  pursuant to Section 39(a) or
forego or  terminate  any such  proceeding  with  respect  to Taxes  indemnified
pursuant to this Section  39(b),  without the prior written  consent of TowerCo,
which consent shall not be unreasonably withheld. If TowerCo requests in writing
that the Tax Indemnitee accept a settlement of a claim offered by the IRS (other
than an offer  conditioned upon the Tax  Indemnitee's  agreement with respect to
any issue wholly or partly  unrelated to the  transactions  contemplated  by the
Transaction  Documents),  the Tax Indemnitee shall either accept such settlement
offer or agree with  TowerCo  that  TowerCo's  liability  pursuant to Section 39
hereof shall be limited to an amount  calculated on the basis of such settlement
offer.  The Tax Indemnitee  shall not be required to appeal any adverse decision
of the United States Tax Court,  a Federal  District  Court,  or any  comparable
trial court.

SECTION 40.       General Provisions.

(a)  Notices.  Whenever  any notice,  demand or request is required or permitted
under this  Agreement,  such notice,  demand or request  shall be in writing and
shall be delivered by hand,  be sent by registered  or certified  mail,  postage
prepaid,   return  receipt  requested,  or  be  sent  by  nationally  recognized
commercial  courier for next business day  delivery,  to the addresses set forth
below,  or to such other  addresses as are specified by written  notice given in
accordance  herewith,  or shall be transmitted  by facsimile  (with a copy to be
sent by  nationally  recognized  courier for next  business day delivery) to the
<PAGE>   77
                                                                              75

number for each Party set forth below their respective  executions hereof, or to
such  other  numbers as are  specified  by written  notice  given in  accordance
herewith.  All  notices,  demands or requests  delivered by hand shall be deemed
given upon the date so delivered; those given by mailing as hereinabove provided
shall be deemed given on the date of deposit in the United  States  Mail;  those
given by commercial courier as hereinabove provided shall be deemed given on the
date of deposit with the commercial courier;  and those given by facsimile shall
be deemed  given on the date of  facsimile  transmittal.  Nonetheless,  the time
period,  if any,  in which a  response,  or action in  response,  to any notice,
demand or request  must be given shall  commence to run from the date of receipt
of the notice, demand or request by the addressee thereof. Any notice, demand or
request not received  because of changed address or facsimile number of which no
notice  was given as  hereinabove  provided  or  because  of  refusal  to accept
delivery shall be deemed  received by the Party to whom addressed on the date of
hand delivery, on the date of facsimile  transmittal,  on the first calendar day
after deposit with  commercial  courier,  or on the third calendar day following
deposit in the United States Mail, as the case may be.

         If to TowerCo:

                  Southern Towers, Inc.
                  c/o SpectraSite Communications, Inc.
                  100 Regency Forest Drive, Suite 400
                  Cary, North Carolina 27511
                  Attention:  General Counsel
                  Telecopy:  (919) 468-8522

                  with a copy to:

                  Paul, Weiss, Rifkind, Wharton & Garrison
                  1285 Avenue of the Americas
                  New York, New York  10019-6064
                  Attention:  Mitchell L. Berg
                               Bruce A. Gutenplan
                  Telecopy:  (212) 757-3990

         If to SBC or any SBC Affiliate:

                  SBC Tower Holdings LLC
                  17330 Preston Road,  Suite #100A
                  Dallas, TX  75252
                  Attention: General Counsel
                  Telecopy: 972-733-2021

                  with a copy to:

                  SBC Communications Inc.
                  175 E. Houston
                  4th Floor
                  San Antonio, TX  78205
                  Attention:  Vice President and Assistant
                                    General Counsel
                  Telecopy: (210) 351-3488
<PAGE>   78

                                                                              76
         If to TowerCo Parent:

                  SpectraSite Holdings, Inc.
                  c/o SpectraSite Communications, Inc.
                  100 Regency Forest Drive, Suite 400
                  Cary, North Carolina 27511
                  Attention:  General Counsel
                  Telecopy:  (919) 468-8522

                  with a copy to:

                  Paul, Weiss, Rifkind, Wharton & Garrison
                  1285 Avenue of the Americas
                  New York, New York  10019-6064
                  Attention:  Mitchell L. Berg
                               Bruce A. Gutenplan
                  Telecopy:  (212) 757-3990

         If to Wireless Guarantor:

                  SBC Wireless, LLC
                  c/o SBC Wireless, Inc.
                  17330 Preston #100A
                  Dallas, TX 75252
                  Attention:  General Counsel
                  Telecopy:  (972) 773-2021

(b)  Facsimile as Writing.  The Parties  expressly  acknowledge  and agree that,
notwithstanding  any  statutory or decisional  law to the contrary,  the printed
product  of a  facsimile  transmittal  shall be  deemed  to be  "written"  and a
"writing" for all purposes of this Sublease.

(c) Binding Effect. This Sublease shall be binding upon and enforceable against,
and shall  inure to the  benefit  of, the  Parties  hereto and their  respective
heirs, legal representatives, successors and permitted assigns.
<PAGE>   79
                                                                              77

(d)  Headings.  The use of headings,  captions  and numbers in this  Sublease is
solely for the convenience of identifying and indexing the various provisions in
this  Sublease and shall in no event be  considered  otherwise in  construing or
interpreting any provision in this Sublease.

(e) WAIVER OF JURY TRIAL.  TO THE MAXIMUM  EXTENT  PERMITTED BY LAW, THE PARTIES
HEREBY KNOWINGLY,  VOLUNTARILY AND  INTENTIONALLY  WAIVE THE RIGHT TO A TRIAL BY
JURY IN RESPECT OF ANY  LITIGATION  BASED  HEREON,  ARISING OUT OF,  UNDER OR IN
CONNECTION  WITH THIS  SUBLEASE,  OR ANY COURSE OF  CONDUCT,  COURSE OF DEALING,
STATEMENT  (WHETHER VERBAL OR WRITTEN) OR ACTION OF EITHER PARTY OR ANY EXERCISE
BY ANY PARTY OF THEIR RESPECTIVE RIGHTS UNDER THIS SUBLEASE (INCLUDING,  WITHOUT
LIMITATION,  ANY ACTION TO  TERMINATE  THIS  SUBLEASE,  AND ANY CLAIM OR DEFENSE
ASSERTING THAT THIS AGREEMENT WAS  FRAUDULENTLY  INDUCED OR IS OTHERWISE VOID OR
VOIDABLE).  THIS WAIVER IS A MATERIAL  INDUCEMENT  FOR THE PARTIES TO ENTER INTO
THIS SUBLEASE.

(f) Exhibits.  Each and every exhibit referred to or otherwise mentioned in this
Sublease is attached to this Sublease and is and shall be construed to be made a
part of this Sublease by such  reference or other mention at each point at which
such  reference or other  mention  occurs,  in the same manner and with the same
effect as if each  exhibit were set forth in full and at length every time it is
referred to or otherwise mentioned.

(g)  Defined  Terms.  Capitalized  terms  used in this  Sublease  shall have the
meanings  ascribed  to them at the point where first  defined,  irrespective  of
where their use occurs, with the same effect as if the definitions of such terms
were set forth in full and at length every time such terms are used.

(h) Pronouns.  Wherever appropriate in this Sublease, personal pronouns shall be
deemed to include the other genders and the singular to include the plural.

(i)  Severability.  If any  term,  covenant,  condition  or  provision  of  this
Sublease,  or the application thereof to any person or circumstance,  shall ever
be held to be invalid or unenforceable, then in each such event the remainder of
this Sublease or the application of such term, covenant,  condition or provision
to any other person or any other  circumstance  (other than those as to which it
shall be invalid or unenforceable) shall not be thereby affected, and each term,
covenant,  condition and provision  hereof shall remain valid and enforceable to
the fullest extent permitted by law.

(j)  Non-Waiver.  Failure by any Party to complain of any action,  non-action or
breach of any other Party shall not constitute a waiver of any aggrieved Party's
rights  hereunder.  Waiver by any Party of any right  arising from any breach of
any other Party shall not  constitute a waiver of any other right arising from a
subsequent breach of the same obligation or for any other default, past, present
or future.

(k)  Rights  Cumulative.  All  rights,  remedies,  powers  and  privileges
conferred  under  this Sublease on the Parties shall be cumulative of and in
addition to, but not  restrictive  of or in lieu of, those conferred by law.
<PAGE>   80
                                                                              78

(l) Time of  Essence.  Time is of the essence of this  Sublease.  Anywhere a day
certain is stated for  payment or for  performance  of any  obligation,  the day
certain so stated enters into and becomes a part of the  consideration  for this
Sublease.  If any date set  forth in this  Sublease  shall  fall on, or any time
period set forth in this  Sublease  shall  expire on, a day which is a Saturday,
Sunday or federal or state holiday,  such date shall  automatically  be extended
to, and the  expiration of such time period shall  automatically  to be extended
to, the next day which is not a Saturday,  Sunday,  federal or state  holiday or
other  non-business day. The final day of any time period under this Sublease or
any deadline  under this Sublease  shall be the specified day or date, and shall
include the period of time through and including such specified day or date.

(m)  Applicable  Law. This Sublease  shall be governed by,  construed  under and
interpreted  and enforced in accordance  with the laws of the State of New York,
without regard to conflicts of law. Notwithstanding the foregoing, to the extent
the application of the law of the state in which the affected Site is located is
mandatory  rather than permissive  (such as, by way of example,  with respect to
the taking of  possession of leased  premises by a lessor or procedural  matters
relating  to the  exercise  of  remedies  with  respect to leased  premises by a
lessor), the laws of such state shall govern.

(n) Entire Agreement. This Sublease, together with all other agreements executed
contemporaneously  herewith,  contains the entire  agreement of the Parties with
respect to the  subject  matter  hereof,  and all  representations,  warranties,
inducements,  promises or agreements, oral or otherwise, between the Parties not
embodied in this Sublease shall be of no force or effect.

(o) Modifications. This Sublease shall not be modified or amended in any respect
except by a written agreement executed by the Parties in the same manner as this
Sublease is executed.

(p) Counterparts. This Sublease 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.

(q)  Attorneys'  Fees.  In the  event  of any  litigation  arising  under  or in
connection with this Sublease, the prevailing Party shall be entitled to recover
from the other Party the expenses of litigation (including reasonable attorneys'
fees, expenses and disbursements) incurred by the prevailing Party.

(r) Authority.  Each Party hereto  warrants and  represents  that such Party has
full and complete authority to enter into this Sublease and that each individual
executing  this  Sublease on behalf of such Party has been fully  authorized  to
execute  this  Sublease  on behalf of such Party and that such Party is bound by
the signature of such representative.

(s) Counsel.  Each Party hereto warrants and represents that such Party has been
afforded  the  opportunity  to be  represented  by  counsel  of  its  choice  in
connection with the execution of this Sublease and has had ample  opportunity to
read, review, and understand the provisions of this Sublease.
<PAGE>   81
                                                                              79

(t) No  Construction  Against  Preparer.  No provision of this Sublease shall be
construed  against or interpreted to the  disadvantage of any Party by any court
or other  governmental or judicial authority by reason of such Party's having or
being deemed to have prepared or imposed such provision.

(u)      Power of Attorney by SBC Group; Authorization.

     (i)  The Sublessors  and each of them,  hereby  irrevocably  constitute and
          appoint SBC (the "Agent") as their agent to enter into, modify,  amend
          or otherwise change this Sublease,  any Site Designation Supplement or
          any of their respective  terms or provisions,  to take all actions and
          to execute all documents necessary or desirable to effect the terms of
          this Sublease,  and to take all actions and to execution all documents
          which may be necessary or desirable in connection  therewith,  to give
          and receive  consents  and all notices  hereunder,  to  negotiate  and
          settle  Claims  for  indemnification,  and to  perform  any  other act
          arising under or  pertaining to the Sublease and the Site  Designation
          Supplements.  The Sublessor,  and each of them,  agree that service of
          process upon the Agent in any action or  proceeding  arising  under or
          pertaining  to the  Sublease  shall be deemed to be valid  service  of
          process  upon  such  Sublessor,  and  each of them,  and any  claim by
          TowerCo  against  the  Sublessors,  or any of them,  in respect to the
          Sublease may be asserted  against,  and settled with,  the Agent.  The
          Agent shall be deemed to have accepted the appointment herein upon its
          execution of this Sublease.

     (ii) Nothing  contained  herein shall be deemed to make the Agent liable to
          the  Sublessors  because  of  service  in its  capacity  as agent.  In
          performing any of its duties hereunder,  the Agent shall not incur any
          liability  to the  Sublessors  for  losses,  damages,  Liabilities  or
          expenses, except for its fraud, willful default or gross negligence.

     (iii)It is expressly  understood and agreed that this power of attorney and
          the  agency  created  hereby  is  coupled  with  an  interest  of  the
          respective  Parties hereto and shall be binding and enforceable on and
          against the respective  successors and assigns of the Sublessors,  and
          each of them,  and this  power of  attorney  shall not be  revoked  or
          terminated  and shall  continue to be binding and  enforceable  in the
          manner provided herein.

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<PAGE>   82

                                                                             S-1



                      SIGNATURE PAGE TO LEASE AND SUBLEASE
         IN WITNESS  WHEREOF,  the  Parties  have  caused  this  Sublease  to be
executed and sealed by their duly authorized  representatives,  all effective as
of the day and year first written above.

                               TOWERCO:

                               SOUTHERN TOWERS, INC.


                               By /s/Glen Spivak
                                 -----------------------------------------------
                                   Glen Spivak
                                    Vice President


                               SOUTHERN TOWERS OF DELAWARE, INC.


                               By /s/Glen Spivak
                                 -----------------------------------------------
                                   Glen Spivak
                                    Vice President


                               SBC TOWER HOLDINGS LLC,
                               a Delaware limited liability company
                               By: New Southwestern Bell Mobile Systems, Inc.,
                                      its Managing Member


                               By /s/Gregory L. Gibson
                                 -----------------------------------------------
                                    Gregory L. Gibson, as attorney-in-fact


                               TOWERCO PARENT:

                               SPECTRASITE HOLDINGS, INC.


                               By /s/Richard Byrne
                                 -----------------------------------------------
                                  Richard Byrne
                                    Executive Vice President


                               WIRELESS GUARANTOR:

                                SBC WIRELESS, LLC


                               By /s/Kathy Rehmer
                                 -----------------------------------------------
                                    Kathy Rehmer, as attorney-in-fact