SONUS NETWORKS INC
EXHIBIT 10.18
<DOCUMENT>
<TYPE>EX-10.18
<SEQUENCE>8
<FILENAME>a2072649zex-10_18.txt
<DESCRIPTION>EXHIBIT 10.18
<TEXT>
<Page>

                                 EXHIBIT 10.18

                                GLOBAL AGREEMENT

     This Global Agreement (this "AGREEMENT") is being entered into effective as
of March 5, 2002 (the "EFFECTIVE DATE"), by and among TR Lookout Partners,
Ltd. ("TRLP"), Collins Campbell Joint Venture ("CCJV"), telecom technologies,
inc. ("TTI"), and Sonus Networks, Inc. ("SONUS"). TRLP, CCJV, TTI, and Sonus
shall be collectively referred to as the "PARTIES".

                                    RECITALS:

     WHEREAS, TTI has entered into several leases (the "LEASES") with TRLP and
CCJV, as landlords, and pursuant to the terms of the Leases, TTI is bound and
obligated to perform all of its obligations under the Leases for the remaining
terms of each of the Leases;

     WHEREAS, TTI is a wholly owned subsidiary of Sonus and due to economic
conditions, requires a reduction in its Richardson, Texas facilities under lease
with TRLP and CCJV (collectively, the "LANDLORDS");

     WHEREAS, the Landlords have agreed to certain lease terminations and/or
modifications in exchange for the agreements set forth herein, the payments by
Sonus to TRLP representing a reimbursement to CCJV of the cost of various tenant
improvements, lease termination, capital expenses, and build out costs in
connection with the premises covered by the lease terminated hereunder, all as
more fully described below, and such other good and valuable consideration; and

     NOW, THEREFORE, in consideration of the covenants and agreements
hereinafter set forth and for other good and valuable consideration, the receipt
and adequacy of which are hereby acknowledged, the Parties have agreed to the
above recitals and as follows:

     1.  Notwithstanding anything to the contrary in this Agreement (or any of
         the agreements including lease agreements referenced herein; hereafter
         such agreements, together with this Agreement, shall be collectively
         referred to as the "DOCUMENTS"), the Documents (inclusive of this
         Agreement) shall NOT be effective until the occurrence of each and
         every one of the following events: (A) the execution and delivery by
         the Parties to each other of (i) this Agreement; (ii) the Termination
         of Office Lease Agreement attached as EXHIBIT "A" hereto; (iii) the
         Termination of Office Lease Agreement, attached as EXHIBIT "B" hereto;
         (iv) the Fifth Amendment to Office Lease Agreement, attached as EXHIBIT
         "C" hereto; (v) the Guarantee, attached as EXHIBIT "D" hereto; (vi) the
         Bill of Sale, attached as EXHIBIT "E" hereto; (vii) the Storage
         Agreement with respect to the Personal Property, attached as EXHIBIT
         "F" hereto; (viii) the Guarantee of Sonus with respect to the
         obligations of TTI under the Bill of Sale and Storage Agreement,
         attached as EXHIBIT "G" hereto; (B) the indefeasible and irrevocable
         payment by Sonus of One Million Dollars ($1,000,000) to TRLP, in care
         of Thompson Realty Investment Corporation ("THOMPSON REALTY"),
         contemporaneous with the payment by TRLP to TTI of such payment
         described in subsection (D) immediately below; (C) the indefeasible and
         irrevocable payment by Sonus to Thompson Realty of $2,500.00,
         representing no less than fifty percent (50%) of all legal fees, costs
         and expenses incurred by counsel for Thompson Realty in connection with
         these matters; and (D) the wire transfer by TRLP at Closing to TTI of
         One Hundred Sixty Five Thousand Two Hundred Thirty-Six and 50/100
         Dollars ($165,236.50) as provided under EXHIBIT "A" to this Agreement,
         contemporaneous with the payment by Sonus to TRLP described in
         subsection (B) immediately above. At Closing, TRLP and CCJV shall
         deliver to Sonus and TTI consents from their respective lenders
         approving the termination, and amendments where applicable, of their
         respective Leases with TTI, as provided herein, which consents shall be
         in the form of EXHIBITS "H" and "I" hereto.

                                     Page 1
<Page>

     2.  On the Effective Date, that certain Office Lease Agreement, dated
         November 14, 2000, as amended by that certain First Amendment to Office
         Lease Agreement, dated as of January, 8, 2001, by and between TRLP and
         TTI, will be terminated and shall be of no further force and effect, in
         accordance with the terms set forth in the Termination of Office Lease
         Agreement, attached hereto as EXHIBIT "A" and incorporated herein for
         all purposes.

     3.  On the Effective Date, those certain Office Lease Agreements described
         below, by and between CCJV and TTI, will be modified and/or terminated
         in accordance with the agreements attached hereto as EXHIBIT "B", and
         EXHIBIT "C", each of which is incorporated herein for all purposes.
         These agreements generally provide for the following:

         a. Suite 1050, Richardson, Texas 75080, approximately 6,618 square feet
            - terminated;
         b. Suite 3000, Richardson, Texas 75080, approximately 38,016 square
            feet - modified to reduce the size of the premises ("LEASE 1");
         c. Suite 339, Richardson, Texas 75080, approximately 2,281 square feet
            - no change in terms ("LEASE 2"); and
         d. Suite 2400, Richardson, Texas 75080, approximately 2,055 square feet
            - no change in terms ("LEASE 3").

     4.  TTI hereby acknowledges and consents to all of the terms and conditions
         of Lease 1, Lease 2, and Lease 3 (collectively, the "OFFICE LEASES"),
         and TTI and Sonus each ratifies, reaffirms, and confirms the
         effectiveness of each of the Office Leases. TTI and Sonus each
         acknowledges that each such party has no claims, counterclaims,
         offsets, credits or defenses to the Leases, and each party's
         performance of its obligations thereunder (to the extent applicable),
         or if TTI or Sonus has any such claims, counterclaims, offsets, credits
         or defenses to the Leases or any transaction related to the Leases, the
         same are hereby waived, relinquished and released in consideration of
         the Parties' mutual agreements set forth in this Agreement.

     5.  On the Effective Date, Sonus will guarantee unconditionally all of the
         obligations and covenants of TTI to CCJV under the three (3) remaining
         leases at the "Atrium on Collins", in accordance with the terms of the
         Guarantee attached hereto as EXHIBIT "D" and incorporated herein for
         all purposes.

     6.  CCJV hereby agrees to exercise good faith efforts to reach a written
         agreement with Hamid Ansari and Anousheh Ansari (collectively, the
         "ANSARIS") providing for a release from the Ansaris in favor of CCJV,
         TTI, and Sonus, with respect to any obligations of such parties, if any
         (with respect to the payment of a profit fee), as provided in that
         certain letter agreement, dated April 4, 1997, executed by CCJV and the
         Ansaris, as amended by that certain letter agreement, dated November 1,
         2000, executed by CCJV and the Ansaris, each of which letter agreements
         was consented to by TTI; PROVIDED, HOWEVER, that if CCJV is unable to
         provide such release to Sonus and TTI, on or prior to the Effective
         Date, then CCJV shall indemnify Sonus and TTI in accordance with the
         terms of the agreement in the form attached hereto as EXHIBIT "J".

     7.  On the Effective Date, TTI agrees that (i) TTI shall transfer to CCJV
         on the earlier of (the "TRANSFER DATE") (A) the date that TTI vacates
         the premises at Suite 3000, 1701 North Collins Boulevard, Richardson,
         Texas 75080, or (B) April 30, 2003 (or such later date, as may be
         extended pursuant to an amendment to the lease, with respect to such
         premises, entered into by TTI and CCJV, thereby extending the term of
         such lease), all of TTI's right, title, and interest in and to certain
         furniture, fixtures, and equipment owned by TTI, substantially in
         accordance with the terms of the bill of sale attached hereto as
         EXHIBIT "E" incorporated herein for all purposes (the "BILL OF SALE"),
         and (ii) TTI shall enter into with CCJV a storage agreement, thereby
         agreeing to store such furniture, fixtures, and equipment, at Suites
         1050 and 2000, at 1701 North Collins Boulevard, Richardson, Texas
         75080, for the period from and after the Effective Date and continuing
         through the earlier of (the "REMOVAL DATE")

                                     Page 2
<Page>

         (A) April 30, 2003, or (B) twenty (20) calendar days after written
         notice from CCJV to TTI to remove such furniture, fixtures and
         equipment, and TTI and CCJV shall execute and deliver a storage
         agreement in the form attached hereto as EXHIBIT "F" and incorporated
         herein for all purposes (the "STORAGE AGREEMENT"). Such Bill of Sale
         and Storage Agreement shall be without recourse or liability to CCJV
         (or its assigns), and shall not constitute, nor be deemed to be, any
         assumption by CCJV (or its assigns) of any obligations, liabilities, or
         indebtedness of TTI (i) on or under such personal property leases or
         (ii) arising out of or in connection with the personal property to be
         transferred under the Bill of Sale. On the Effective Date, Sonus shall
         execute and deliver to CCJV a Guarantee in the form attached hereto as
         EXHIBIT "G", thereby guaranteeing all of TTI's obligations to CCJV (or
         its assigns) with respect to the Bill of Sale, the Storage Agreement,
         and TTI's obligations to CCJV (or its assigns) in this paragraph 7.

     8.  On the Effective Date, Sonus shall pay to Thompson Realty the sum of
         $2,500 representing no less than fifty percent (50%) of the legal fees
         incurred by counsel for Thompson Realty in connection with this these
         transactions and matters.

     9.  Each Party hereto hereby makes the following representations and
         warranties to each other Party, each of which is material, is being
         relied upon by each of the Parties hereto, and is true as of the date
         hereof: (i) this Agreement (and the Documents) has been duly and
         validly executed and delivered by such party; (ii) no further action of
         any kind or nature will be or is necessary on the part of such party,
         or any other person whomsoever, to make this Agreement (and the
         Documents) valid, binding and enforceable upon such party in accordance
         with the terms hereof; (iii) this Agreement (and the Documents) has
         been consented to by TRLP's and CCJV's lender and is thereby authorized
         by such lenders; and (iv) this Agreement (and the Documents)
         constitutes a legal, valid and binding obligation of such Party,
         enforceable in accordance with the terms hereof or as otherwise
         provided by law.

     10. It is the mutual intent of all of the Parties hereto that the Documents
         are, and shall be, final, conclusive, binding, enforceable and
         non-terminable as of, and from and after, the Effective Date, subject
         to the conditions precedent to paragraph 1 of this Agreement.

     11. Each of the Parties hereto hereby covenants and agrees to do such acts
         and things and, in connection therewith, to execute and deliver such
         documents and instruments as reasonably may be required for effecting
         and otherwise carrying out the purposes of the transactions covered and
         contemplated hereby.

     12. No Party hereto may assign any of its rights or delegate any of its
         duties hereunder without the prior written notice of the other Parties
         hereto, and any such assignment or delegation without the prior written
         notice shall be void ab initio.

     13. All terms and provisions of the Documents shall be binding upon and
         inure to the benefit of the respective Parties to each of the Documents
         and their respective transferees.

     14. The Documents may be executed in one or more counterparts, all of which
         taken together shall constitute one instrument. Signatures delivered by
         telecopy shall be binding, and the Parties hereto agree to send to the
         other originals of this Agreement (and the Documents) within
         twenty-four (24) hours of the closing of these transactions.

     15. The Documents are made and entered into in the State of Texas, and the
         laws of said state shall govern the validity and interpretation hereof
         and the performance of the Parties hereto of their respective duties
         and obligations hereunder.

     16. No breach of any provision hereof (or in the Documents) may be waived
         unless in writing executed by the affected Party(s) hereto and the
         waiver of any one breach shall not be deemed to be a waiver of any
         other breach of the same or any other provision hereof.

                                     Page 3
<Page>

     17. The Documents may be amended only by a written agreement executed by
         the respective Parties to each of this Agreement and the applicable
         Parties to the other Documents.

     18. The Documents are entered into for the express benefit of the Parties
         hereto, and it is not intended and shall not be deemed to create in any
         other person any rights or interest whatsoever, including without
         limitation, any rights to enforce the terms hereof.

     19. This Agreement (together with the other Documents) embodies the entire
         understanding of the Parties with respect to the matters set forth
         herein (and therein); and there are no further or other agreements or
         understandings, written or oral, in effect between the Parties hereto
         relating to the subject matter hereof, unless expressly referred to by
         reference herein or executed concurrently herewith.

     20. The Parties agree that the payments made, and obligations incurred, by
         Sonus to, or in favor of, TRLP constitutes reasonable equivalent value
         for the termination and modification of the lease agreements described
         herein, and agreements set forth herein (in accordance with the terms
         of this Agreement) and the restructuring of obligations provided for
         herein by TRLP and CCJV to Sonus and TTI. Sonus represents, warrants,
         and covenants that (i) the $1 million payment to TRLP as provided
         herein shall be paid solely from the funds of Sonus, and not the funds
         of TTI; (ii) the $1 million payment shall be wire-transferred by Sonus
         to TRLP, in care of Thompson Realty, on the Effective Date; and (iii)
         the $1 million payment represents a reasonable calculation of the costs
         to reimburse TRLP for its tenant improvements, lease termination costs,
         capital expenses, and build-out costs in connection with the premises
         covered by the leases terminated under this Agreement. The Parties
         agree that Hughes & Luce, L.L.P., shall serve as the escrow agent at
         the Closing of the transactions contemplated hereunder, and the escrow
         agent shall make the contemporaneous wire transfers described in this
         paragraph to the respective Parties at the Closing. At the Closing,
         CCJV shall wire transfer to TTI the sum of $165,236.50, as provided
         under EXHIBIT "A" of this Agreement, and Sonus shall wire transfer to
         TRLP, in care of Thompson Realty, the sum of $1,000,000, as provided in
         this Agreement.

     21. If the incurrence or payment of the obligations by either TTI or Sonus
         or the transfer to the Landlords of any property should for any reason
         subsequently be declared to be void or voidable under any state or
         federal law relating to creditors' rights, including provisions of the
         Bankruptcy Code relating to fraudulent conveyances, preferences, or
         other voidable or recoverable payments of money or transfers of
         property (collectively, a "VOIDABLE TRANSFER"), and if the Landlords
         are required to repay or restore, in whole or in part, any such
         Voidable Transfer, or elect to do so upon the reasonable advice of its
         or their counsel, then, as to any such Voidable Transfer, or the amount
         thereof that the Landlords are required or elect to repay or restore,
         and as to all reasonable costs, expenses, and attorneys fees of the
         Landlords related thereto, the liabilities and obligations of TTI and
         Sonus, arising out of or in any way related to the termination of lease
         obligations provided for above, or other releases granted in connection
         with this Agreement, automatically shall be revived, reinstated, and
         restored and shall exist as though such Voidable Transfer had never
         been made and this Agreement and the Documents had not been executed;
         provided, however, that notwithstanding the foregoing, (i) the payments
         made pursuant to paragraph 1 of this Agreement by the respective
         Parties hereto shall be returned or applied against any payments due or
         which became due after the Effective Date; (ii) all rights, titles, and
         interests of TTI in such leases terminated under the relevant Documents
         shall nonetheless be terminated and of no further force or effect upon
         the Effective Date of this Agreement; (iii) the Fifth Amendment to
         Office Lease Agreement shall remain in full force and effect and
         binding upon the Parties (but the liabilities of TTI with respect to
         such Office Lease Agreement prior to such Fifth Amendment shall be
         reinstated); and (iv) the Bill of Sale and Storage Agreement shall
         remain effective and binding upon such Parties.

                                     Page 4
<Page>

     22. TTI and Sonus each hereby acknowledges that as of the date hereof it
         has no defense, counterclaim, offset (except to the extent of payments
         made pursuant to this Agreement), cross-complaint, claim or demand of
         any kind or nature whatsoever that can be asserted to reduce or
         eliminate all or any part of its liability to repay the obligations or
         to seek affirmative relief or damages of any kind or nature from the
         Landlords or Thompson Realty, Thompson Realty Corporation, or each of
         the foregoing parties' respective affiliates, participants, partners,
         directors, officers, agents, employees, representatives or attorneys.
         TTI and Sonus each hereby voluntarily and knowingly releases and
         forever discharges the Landlords, Thompson Realty, Thompson Realty
         Corporation, and each of the foregoing parties' respective affiliates,
         participants, partners, agents, representatives, officers, directors,
         attorneys, employees, successors and assigns (collectively, the
         "LANDLORD RELEASEE GROUP"), from all possible claims, demands, actions,
         causes of action, damages, costs, expenses, and liabilities whatsoever,
         known or unknown, anticipated or unanticipated, suspected or
         unsuspected, fixed, contingent, or conditional, at law or in equity,
         originating in whole or in part on or before the date this Agreement
         becomes effective (collectively, the "LANDLORD CLAIMS"); PROVIDED,
         HOWEVER, that notwithstanding the foregoing, nothing herein shall
         release the Landlord Releasee Group from any obligations,
         representations, or covenants set forth in this Agreement, Leases 1, 2,
         and 3, or any of the other Documents, to the extent applicable to the
         particular member of the Landlord Releasee Group.

     23. Each of TTI and Sonus hereby covenants and agrees never to institute
         any action or suit at law or in equity, nor institute, prosecute, or in
         any way aid in the institution or prosecution of any claim, action or
         cause of action, rights to recover debts or demands of any nature
         against the Landlord Releasee Group, or any one of them, arising out of
         or related to the Landlord Claims.

     24. CCJV, TRLP, Thompson Realty, and Thompson Realty Corporation each
         hereby voluntarily and knowingly releases and forever discharges Sonus
         and TTI, and each of the foregoing parties' respective affiliates,
         participants, partners, agents, representatives, officers, directors,
         attorneys, employees, successors and assigns (collectively, the "TENANT
         RELEASEE GROUP"), from all possible claims, demands, actions, causes of
         action, damages, costs, expenses, and liabilities whatsoever, known or
         unknown, anticipated or unanticipated, suspected or unsuspected, fixed,
         contingent, or conditional, at law or in equity, originating in whole
         or in part on or before the date this Agreement becomes effective
         (collectively, the "TENANT CLAIMS"); PROVIDED, HOWEVER, that
         notwithstanding the foregoing, nothing herein shall release the Tenant
         Releasee Group from any obligations, representations, or covenants set
         forth in this Agreement, Lease 1, 2 and 3, the Guarantees, the Bill of
         Sale, the Storage Agreement, or any of the other Documents, to the
         extent applicable to the particular member of the Tenant Releasee
         Group.

     25. Each of CCJV, TRLP, Thompson Realty, and Thompson Realty Corporation
         hereby covenants and agrees never to institute any action or suit at
         law or in equity, nor institute, prosecute, or in any way aid in the
         institution or prosecution of any claim, action or cause of action,
         rights to recover debts or demands of any nature against the Tenant
         Releasee Group, or any one of them, arising out of or related to the
         Tenant Claims.

     This Agreement is executed as of March 5, 2002.

                        TR LOOKOUT PARTNERS, LTD.,
                         a Texas limited partnership

                        By:   Thompson Realty Investment Corporation,
                                general partner

                                     Page 5
<Page>

                                By:      /s/ W.T. Field
                                         ------------------------
                                         W.T. Field, President

                        COLLINS CAMPBELL JOINT VENTURE,
                            a Texas general partnership

                           By:      Jaytex Properties, Ltd.,
                                     a Texas limited partnership

                                    By:      JRS Management, Inc.

                                             By:      /s/ W.T. Field
                                                      ----------------------
                                                      W.T. Field, President

                           telecom technologies, inc.,
                            a Texas corporation

                           By:     /s/ G.M. Eastep
                                   ------------------------
                           Name:   G.M. Eastep
                                   ------------------------
                           Title:  Vice President and Chief Operating Officer
                                   -------------------------------------------

                           SONUS NETWORKS, INC.,
                            a Delaware corporation

                           By:     /s/ Peter S. Hemme
                                   ------------------------
                           Name:   Peter S. Hemme
                                   ------------------------
                           Title:  Vice President and Controller
                                   -----------------------------

AGREED AS TO PARAGRAPHS 24
AND 25 ONLY:

TH0MPSON REALTY INVESTMENT
CORPORATION, a Texas
corporation

By:     /s/ W.T. Field
        ------------------------
Name:   W.T. Field
        ------------------------
Title:  President
        ------------------------

TH0MPSON REALTY CORPORATION,
a Texas corporation

By:     /s/ W.T. Field
        ------------------------

                                     Page 6
<Page>

Name:   W.T. Field
        ------------------------
Title:  President
        ------------------------

                                     Page 7
<Page>

                                   EXHIBIT "A"

                      TERMINATION OF OFFICE LEASE AGREEMENT

     This Termination of Office Lease Agreement (this "Termination") is being
entered into as of February 28, 2002, by and between TR Lookout Partners, Ltd.
("Landlord") and telecom technologies, inc. ("Tenant").

                                R E C I T A L S:

     WHEREAS, Landlord and Tenant entered into that certain Office Lease
Agreement dated November 14, 2000, as amended by that certain First Amendment to
Office Lease Agreement dated as of January 8, 2001 (collectively, the "Lease")
with respect to approximately 119,966 square feet of space plus the Basement
Area (as defined and specified in the Lease) (the "Demised Premises") at 1301 E.
Lookout Drive, Richardson, Texas 75080;

     WHEREAS, Tenant has chosen not to occupy the Demised Premises;

     WHEREAS, Landlord and Tenant, among others, have entered into the terms of
a certain global agreement of even date herewith (the "Global Agreement"), and
Landlord and Tenant acknowledge and agree that the terms of the Global Agreement
shall be binding on the parties hereto;

     WHEREAS, Landlord and Tenant have reached certain agreements with respect
to the termination of the Lease; and

     WHEREAS, Landlord and Tenant now desire to set forth these certain
agreements with respect to the termination of the Lease and certain other
related matters.

     NOW, THEREFORE, in consideration of the covenants and agreements
hereinafter set forth and for other good and valuable consideration, the receipt
and adequacy of which are hereby acknowledged, Landlord and Tenant covenant and
agree to the above recitals and as follows:

     1.  Subject to the occurrence of all of the events set forth in the Global
Agreement in Paragraph 1 thereof, the Lease is terminated and Tenant shall no
longer have any right to occupy and/or use the Demised Premises.

     2.  Subject to the occurrence of all of the events set forth in the Global
Agreement in Paragraph 1 thereof, the Landlord hereby releases Tenant, Tenant's
parent company, Sonus Networks, Inc., and any and all guarantors of Tenant's
obligations under the Lease and from each and every obligation contained in the
Lease, including, but not limited to, the cost of various tenant improvements,
capital expenses, lease termination costs, and build out costs, or any guaranty
thereof. Subject to the occurrence of all of the events set forth in Paragraph 1
of the Global Agreement, Tenant hereby releases Landlord from any and all claims
Tenant might assert against Landlord relating in any way to the Lease or to
Tenant's occupancy of the Demised Premises. At closing, Landlord shall refund by
wire transfer to Tenant the prepaid rent held by Landlord in the amount of
$165,236.50.

     3.  The Global Agreement, and all of the terms therein, shall be
incorporated herein for all purposes.

                             EXHIBIT "A" Page 1 of 2
<Page>

     EXECUTED as of the date herein first written above.

                             LANDLORD:

                             TR Lookout Partners, Ltd.,
                              a Texas limited partnership

                             By:      Thompson Realty Investment Corporation,
                                          general partner

                                      By:     /s/ W.T. Field, President
                                              ------------------------
                                               W.T. Field, President

                             TENANT:

                             telecom technologies, inc.,
                               a Texas corporation

                             By:      /s/ G.M. Eastep
                                      --------------------------
                             Name:    G.M. Eastep
                                      --------------------------
                             Title:   Vice President and Chief
                                      Operating Officer
                                      --------------------------

                             EXHIBIT "A" Page 2 of 2
<Page>

                                   EXHIBIT "B"

                      TERMINATION OF OFFICE LEASE AGREEMENT

     This Termination of Office Lease Agreement (this "Termination") is being
entered into as of February 28, 2002, by and between Collins Campbell Joint
Venture ("Landlord") and telecom technologies, inc. ("Tenant").

                                R E C I T A L S:

     WHEREAS, Landlord and Tenant entered into that certain Office Lease
Agreement, dated January 25, 2000, as amended by that certain First Amendment to
Office Lease Agreement dated July 10, 2000 (collectively, the "Lease"),
concerning approximately 6,618 square feet of space (the "Premises") at 1701 N.
Collins, Suite 1050, Richardson, Dallas County, Texas 75080;

     WHEREAS, Tenant has chosen to vacate the Premises;

     WHEREAS, Landlord and Tenant, among others, have entered into the terms of
a certain global agreement of even date herewith (the "Global Agreement"), and
Landlord and Tenant acknowledge and agree that the terms of the Global Agreement
shall be binding on the parties hereto;

     WHEREAS, Landlord and Tenant have reached certain agreements with respect
to a termination of the Lease; and

     WHEREAS, Landlord and Tenant now desire to set forth these certain
agreements with respect to the termination of the Lease and certain other
related matters.

     NOW, THEREFORE, in consideration of the covenants and agreements
hereinafter set forth and for other good and valuable consideration, the receipt
and adequacy of which are hereby acknowledged, Landlord and Tenant covenant and
agree to the above recitals, and as follows:

     1.  Subject to the occurrence of all of the events set forth in the Global
Agreement in Paragraph 1 thereof, the Lease is terminated and Tenant shall no
longer have any right to occupy and/or use the Premises.

     2.  Subject to the occurrence of all of the events set forth in the Global
Agreement in Paragraph 1 thereof, Landlord hereby releases Tenant, Tenant's
parent company, Sonus Networks, Inc., and any and all guarantors of Tenant's
obligations under the Lease and from each and every obligation contained in the
Lease, including, but not limited to, the cost of various tenant improvements,
capital expenses, lease termination costs, and build out costs, or any guaranty
thereof. Subject to the occurrence of all of the events set forth in the Global
Agreement in Paragraph 1 thereof, Tenant hereby releases Landlord from any and
all claims Tenant might assert against Landlord relating in any way to the Lease
or to Tenant's occupancy of the Premises.

     3.  The Global Agreement, and all of the terms therein, shall be
incorporated herein for all purposes.

                             EXHIBIT "B" Page 1 of 2
<Page>

     EXECUTED as of the date herein first written above.

                             LANDLORD:

                             Collins Campbell Joint Venture,
                                     a Texas general partnership

                             By:      Jaytex Properties, Ltd.,
                                      a Texas limited partnership

                                      By:      JRS Management, Inc.,
                                               a Texas corporation

                                               By:      /s/ W.T. Field
                                                        ---------------------
                                                        W.T. Field, President

                             TENANT:

                             telecom technologies, inc.,
                              a Texas corporation

                             By:      /s/ G.M. Eastep
                                      --------------------------
                             Name:    G.M. Eastep
                                      --------------------------
                             Title:   Vice President and Chief Operating
                                      Officer
                                      ------------------------------------

                             EXHIBIT "B" Page 2 of 2
<Page>

                                   EXHIBIT "C"

                    FIFTH AMENDMENT TO OFFICE LEASE AGREEMENT

     THIS FIFTH AMENDMENT TO OFFICE LEASE AGREEMENT (this "Fifth Amendment") is
made and entered into effective as of February 28, 2002, by and between Collins
Campbell Joint Venture ("Landlord") and telecom technologies, inc. ("Tenant").

                                 R E C I T A L S

     WHEREAS, Landlord and Tenant entered into that certain Office Lease
Agreement, dated as of April 4, 1997, as amended by (i) that certain First
Amendment to Office Lease Agreement, dated as of November 1, 1997; (ii) those
certain Second and Third Amendments to Office Lease Agreement, each dated as of
July 1, 1998; and (iii) that certain Fourth Amendment to Office Lease Agreement,
dated February 1, 1999 (collectively, the "Lease"), with respect to certain
Premises defined therein and commonly known as Suite 3000 at 1701 North Collins
Blvd., Richardson, Dallas County, Texas 75080, which Lease is incorporated
herein by reference;

     WHEREAS, Landlord and Tenant, among others, have entered into the terms of
a certain global agreement of even date herewith (the "GLOBAL AGREEMENT"), and
Landlord and Tenant acknowledge and agree that the terms of the Global Agreement
shall be binding on the parties hereto;

     WHEREAS, Landlord and Tenant desire to further amend the Lease to reduce
the size of the Premises.

     NOW, THEREFORE, in consideration of the mutual agreements herein set forth,
the mutual agreements set forth in the Lease, and other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged,
Landlord and Tenant have agreed, and do hereby agree, to the above Recitals, and
as follows, subject to the occurrence of all of the events set forth in
Paragraph 1 of the Global Agreement:

     1.  All terms used herein and not specifically defined shall have the same
         meanings herein as is ascribed to them in the Lease.

     2.  The Premises are hereby reduced to approximately 20,227 square feet of
         rentable area by deleting approximately 17,789 square feet of rentable
         area on the second floor, such "Give Back Space" being described on
         Exhibit "A", attached hereto and incorporated herein for all purposes.

     3.  Basic rental is decreased from $3,909,279.04 to $3,475,939.00.

     4.  The monthly rental installment is decreased as set forth below:

         Monthly from March 1, 2002 through October 31, 2002 - $35,043.28
         Monthly from November 1, 2002 through April 30, 2003 - $35,397.25

     5.  Tenant's option to extend the term of the Lease set forth in Rider 101
         is hereby eliminated and of no further force or effect.

     6.  Except as herein provided to the contrary, Tenant's lease of the
         Premises from Landlord shall be on the same terms and conditions as
         those specified in the Lease.

     7.  The Lease (as amended by this Fifth Amendment) remains in full force
         and effect and is hereby ratified and affirmed.

                             EXHIBIT "C" Page 1 of 2
<Page>

     8.  All notices required to be sent to the Tenant shall also be sent to
         Sonus Networks, Inc., 5 Carlisle Road, Westford, Massachusetts 01886;
         Attention: Chief Financial Officer.

     9.  The Global Agreement, and all of the terms therein, shall be
         incorporated herein for all purposes. To the extent that there is a
         conflict between the terms of this Fifth Amendment and the terms of the
         Global Agreement with respect to the relevant subject matter, the terms
         of this Fifth Amendment shall control.

     IN WITNESS WHEREOF, this Fifth Amendment is hereby executed as of the day
and year first set forth above.

                             LANDLORD:

                             COLLINS CAMPBELL JOINT VENTURE,
                              a Texas general partnership

                             By:  Jaytex Properties, Ltd.,
                                   a Texas limited partnership

                                  By:  JRS Management, Inc.

                                               By:      /s/ W.T. Field
                                                        ---------------------
                                                        W.T. Field, President

                             TENANT:

                             telecom technologies, inc.,
                              a Texas corporation

                             By:      /s/ G.M. Eastep
                                      --------------------------
                             Name:    G.M. Eastep
                                      --------------------------
                             Title:   Vice President and Chief Operating
                                      Officer
                                      ------------------------------------

                             EXHIBIT "C" Page 2 of 2
<Page>

            EXHIBIT "A" TO FIFTH AMENDMENT TO OFFICE LEASE AGREEMENT

          [DESCRIPTION OF "GIVE BACK SPACE" TO BE PROVIDE BY LANDLORD]'

      EXHIBIT "A" TO FIFTH AMENDMENT TO OFFICE LEASE AGREEMENT Page 1 of 2
<Page>

                                   EXHIBIT "D"

                                    GUARANTEE

     In connection with that certain Global Agreement, dated as of March 5,
2002, by and among TR Lookout Partners, Ltd., Collins Campbell Joint Venture,
telecom technologies, inc., Sonus Networks, Inc., the undersigned hereby
unconditionally guarantees the full payment and performance of and agrees to pay
and perform as primary obligor all liabilities, obligations and duties
(including, but not limited to, payment of rent) imposed upon telecom
technologies, inc. ("Tenant") under the terms of those three (3) certain leases
(collectively, the "Leases"), as more fully described below, as if the
undersigned had executed the Leases, as Tenant thereunder:

                                GUARANTEED LEASES

     1.  Office Lease Agreement, dated April 4, 1997, by and between Landlord
         and Tenant, as amended by that certain Fourth Amendment to Office Lease
         Agreement dated February 1, 1999, to be amended by that certain Fifth
         Amendment to Office Lease Agreement, concerning approximately 20, 227
         square feet, Suite 3000, Richardson, Texas 75080;

     2.  Office Lease Agreement, dated January 25, 2000, by and between Landlord
         and Tenant, concerning approximately 2,281 square feet, Suite 339,
         Richardson, Texas 75080; and

     3.  Office Lease Agreement, dated October 14, 1999, as amended by that
         certain First Amendment to Office Lease Agreement dated June 15, 2000,
         by and between Landlord and Tenant, concerning approximately 2,055
         square feet, Suite 2400, Richardson, Texas 75080.

     The undersigned hereby waives notice of acceptance of this guarantee and
all other notices in connection herewith or in connection with the liabilities,
obligations, and duties guaranteed hereby, including notices of default by
Tenant under the Leases, and waives diligence, presentment, and suit on the part
of Collins Campbell Joint Venture ("Landlord") in the enforcement of any
liability, obligation or duty guaranteed hereby.

     The undersigned further agrees that Landlord shall not be first required to
enforce against Tenant or any other person any liability, obligation or duty
guaranteed hereby before seeking enforcement thereof against the undersigned.
Suit may be brought and maintained against the undersigned by Landlord to
enforce any liability, obligation or duty guaranteed hereby without joinder of
Tenant or any other person. The liability of the undersigned shall not be
affected by any indulgence, compromise, settlement or variation of terms which
may be extended to the Tenant by the Landlord or agreed upon by the Landlord and
the Tenant, and shall not be affected by any termination of the Leases, to the
extent that the Tenant thereafter continues to be liable thereunder. Landlord
and Tenant, without notice to or consent by the undersigned, may at any time or
times enter into such modifications, extensions, amendments, or other covenants
respecting the Leases, as they may deem appropriate and the undersigned shall
not be released thereby, but shall continue to be fully liable for the payment
and performance of all liabilities, obligations and duties of Tenant under the
Leases, as so further modified, extended or amended; PROVIDED, HOWEVER, that the
undersigned shall not be bound by any modifications, extensions, amendments, or
any other covenants respecting the Leases prior to Landlord's notice to the
undersigned of same, and upon notice to the undersigned of the foregoing, the
undersigned shall be bound by and liable to Landlord under the terms thereof.
Notice to the undersigned shall be sufficient, if sent to Sonus Networks, Inc.,
5 Carlisle Road, Westford, Massachusetts 01886; Attention: Chief Financial
Officer.

     This agreement shall be binding upon the undersigned and the successors,
heirs, executors, and administrators of the undersigned, and shall inure to the
benefit of the Landlord and its heirs, executors, administrators and assigns.

                             EXHIBIT "D" Page 1 of 2
<Page>

     EXECUTED this 5th day of March, 2002.

                             Guarantor:

                             Sonus Networks, Inc.,
                              a Delaware corporation

                             By:      /s/ Peter S. Hemme
                                      --------------------------
                             Name:    Peter S. Hemme
                                      --------------------------
                             Title:   Vice President and Controller
                                      --------------------------

                             EXHIBIT "D" Page 2 of 2
<Page>

                                   EXHIBIT "E"

                    BILL OF SALE OF CERTAIN PERSONAL PROPERTY

     This Bill Of Sale Of Certain Personal Property (this "BILL OF SALE") is
made this 30th day of April, 2003, by telecom technologies, inc., a Texas
corporation ("SELLER"), to and in favor of Collins Campbell Joint Venture
("PURCHASER"), and Sonus Networks, Inc. ("SONUS").

     WHEREAS, Seller, Sonus, and Purchaser, among others, have entered into the
terms of a certain global agreement, dated March 5, 2002, (the "GLOBAL
AGREEMENT"), and Seller, Sonus, and Purchaser acknowledge and agree that the
terms of the Global Agreement shall be binding on the parties hereto;

     WHEREAS, Seller has sold to Purchaser, and Purchaser has agreed to purchase
from Seller, various items of furniture, fixtures, and equipment, and other
personal property located on the premises at Suite 3000, 1701 North Collins
Boulevard, Richardson, Texas 75080, which are more particularly described on
EXHIBIT "A" attached to this Bill of Sale and made a part hereof (collectively,
the "PERSONAL PROPERTY").

     NOW, THEREFORE, for and in consideration of the payment of in the amount of
Ten and No/100 Dollars ($10.00) and other good and valuable consideration,
including the mutual covenants and agreements between and among Seller, Sonus,
and Purchaser in the Global Agreement, the receipt and sufficiency of which are
hereby acknowledged, and in further consideration of the mutual covenants and
agreements contained herein, Seller, Sonus, and Purchaser hereby agree to the
above recitals, and Seller does hereby sell, assign, transfer and convey to
Purchaser and its successors and assigns, all of the Personal Property. The
parties hereto agree that to the extent that such sale of assets provided
hereunder requires that sales tax be paid to any appropriate taxing authorities
on account of such transaction, the Purchaser agrees to assume such obligations.

     TO HAVE AND TO HOLD the Personal Property unto Purchaser, its successors
and assigns, for their exclusive use and benefit forever. Seller warrants that
it has good and marketable title to the Personal Property, free and clear of all
mortgages, liens, charges and encumbrances (including any ad valorem taxes) as
of the effective date of this Bill of Sale.

     Seller hereby assigns to Purchaser any and all service agreements,
warranties, operating agreements, maintenance agreements, manuals, plans, and
all similar and other documents relating to the Personal Property which are in
the possession or under the control of Seller, to the extent that the same may
be assigned (collectively, "SERVICE AGREEMENTS"). Seller shall deliver to
Purchaser copies of all of the Service Agreements at the time of the closing of
the sale, unless otherwise agreed to by Seller and Purchaser in writing.

     Such transfers and assignments provided herein shall be without recourse or
liability to the Purchaser, and shall not constitute, nor be deemed to be, any
assumption by the Purchaser of any obligations, liabilities, or indebtedness of
the Seller arising out of or in connection with the Personal Property or Service
Agreements to be transferred under this Bill of Sale.

     This instrument and the Documents (as defined in the Global Agreement)
contain the entire agreement and understanding between Purchaser and Seller as
to the Personal Property conveyed by this Bill of Sale. No addition, or
amendment, alteration, modification or waiver of, any provisions of this Bill of
Sale shall be of any force or effect unless in writing and signed by Purchaser
and Seller or their duly authorized representatives.

                             EXHIBIT "E" Page 1 of 2
<Page>

     Sonus agrees to indemnify and hold harmless the Purchaser, and pay
Purchaser any losses, costs, fees, liabilities or expense (including attorney's
fees) arising out of Seller's failure to meet its obligations under this
agreement.

     IN WITNESS WHEREOF, Seller, Sonus, and Purchaser have caused this
instrument to be duly executed as of the date first written above.

                             SELLER:

                             telecom technologies, inc.,
                                a Texas corporation

                             By:
                                     ------------------------
                             Name:
                                     ------------------------
                             Title:
                                     ------------------------

                             SONUS:

                             SONUS NETWORKS, INC.,
                                a Delaware corporation

                             By:
                                     ------------------------
                             Name:
                                     ------------------------
                             Title:
                                     ------------------------

                             PURCHASER:

                             COLLINS CAMPBELL JOINT VENTURE,
                              a Texas general partnership

                             By:      Jaytex Properties, Ltd.,
                                       a Texas limited partnership

                                      By:      JRS Management, Inc.

                                               By:
                                                        ----------------------
                                                        W.T. Field, President

                             EXHIBIT "E" Page 2 of 2
<Page>

                           EXHIBIT "A" TO BILL OF SALE

                            LIST OF PERSONAL PROPERTY

                 [TO BE PROVIDED BY TELECOM TECHNOLOGIES, INC.]

                             EXHIBIT "E" Page 3 of 2
<Page>

                                   EXHIBIT "F"

                     STORAGE AGREEMENT OF PERSONAL PROPERTY

     This Storage Agreement of Personal Property (this "STORAGE AGREEMENT") is
made this 5th day of March, 2002, by telecom technologies, inc., a Texas
corporation ("TENANT"), to and in favor of Collins Campbell Joint Venture
("LANDLORD").

                                   WITNESSETH:

     That, for and in consideration of the sum of Ten and No/100 Dollars
($10.00) and other good and valuable consideration, the receipt and sufficiency
of which are hereby acknowledged by Tenant, Tenant and Landlord agree that
Tenant may store all of the personal property (the "PERSONAL PROPERTY"),
described on EXHIBIT "A" hereto.

     Tenant and Landlord agree that Tenant shall have the right to store the
Personal Property, without any fee or charge payable to Landlord, for the period
from the effective date of that certain Global Agreement of even date herewith,
by and among Tenant, Landlord, and others, and continuing for the period through
and including the earlier of (i) April 30, 2003, or (ii) the Removal Date (as
defined below).

     Upon twenty (20) calendar days' prior written notice by the Landlord to the
Tenant (the "REMOVAL DATE"), Tenant shall immediately thereafter remove all of
the Personal Property from the premises of the Landlord, and the Tenant shall
indemnify and hold harmless the Landlord from any damages, losses, or claims of
the Landlord, caused by the removal of the Personal Property from the premises
of the Landlord.

     At any time or from time to time after the date hereof, the parties shall
execute and deliver or cause to be executed and delivered to each other such
other instruments and take or cause to be taken such other actions as may
reasonably be requested in order to carry out the intent and purposes of this
Storage Agreement.

     During the term of this Storage Agreement, Tenant shall maintain and insure
the Personal Property.

     In the event that Landlord enters into a new lease with one or more tenants
for the space where the Personal Property is presently stored, Tenant agrees to
exercise best efforts to reach agreements with such Tenants for the sale and/or
lease of the Personal Property, upon reasonable commercial terms acceptable to
such parties, to facilitate the efforts of the Landlord in leasing such space to
the new tenants.

     Such right of storage shall be without recourse or liability to Landlord
(or its successors and assigns), and shall not constitute, nor be deemed to be,
any assumption by Landlord (or its successors and assigns) of any obligations,
liabilities, or indebtedness of Tenant on or under the Personal Property Leases.

     No addition, or amendment, alteration, modification or waiver of, any
provisions of this Storage Agreement shall be of any force or effect unless in
writing and signed by Tenant and Landlord or their duly authorized
representatives.

                             EXHIBIT "F" Page 1 of 2
<Page>

     IN WITNESS WHEREOF, the undersigned have caused this instrument to be duly
executed as of the date first written above.

                             TENANT:

                             telecom technologies, inc.,
                              a Texas corporation

                             By:     /s/ Peter S. Hemme
                                     ------------------------
                             Name:   Peter S. Hemme
                                     ------------------------
                             Title:  Treasurer
                                     ------------------------

                             LANDLORD:

                             COLLINS CAMPBELL JOINT VENTURE,
                              a Texas general partnership

                             By:      Jaytex Properties, Ltd.,
                                       a Texas limited partnership

                                      By:      JRS Management, Inc.

                                               By: /s/ Kelly P.B. Drabbs
                                                   ----------------------
                                                   Vice President

EXHIBITS

A    -   List of Personal Property [TO BE PROVIDED BY TENANT]

                             EXHIBIT "F" Page 2 of 2
<Page>

                                   EXHIBIT "G"

                                    GUARANTEE

     In connection with that certain Global Agreement, dated as of March 5,
2002 (the "Global Agreement"), by and among TR Lookout Partners, Ltd., Collins
Campbell Joint Venture ("CCJV"), telecom technologies, inc. ("TTI"), Sonus
Networks, Inc., the undersigned hereby unconditionally guarantees the full
payment and performance of and agrees to pay and perform as primary obligor all
liabilities, obligations and duties (including, but not limited to, payment of
rent) imposed upon telecom technologies, inc. ("TTI") under the terms of the
following agreements (collectively, the "Agreements"), as if the undersigned had
executed the Agreements:

                              GUARANTEED AGREEMENTS

     1.  The obligations of TTI to CCJV under Paragraph 7 of the Global
         Agreement;

     2.  The obligations of TTI to CCJV under the Bill of Sale, attached as
         Exhibit "E" to the Global Agreement; and

     3.  The obligations of TTI to CCJV under the Storage Agreement, attached as
         Exhibit "F" to the Global Agreement.

     The undersigned hereby waives notice of acceptance of this guarantee and
all other notices in connection herewith or in connection with the liabilities,
obligations, and duties guaranteed hereby, including notices of default by TTI
under the Agreements, and waives diligence, presentment, and suit on the part of
CCJV in the enforcement of any liability, obligation or duty guaranteed hereby.

     The undersigned further agrees that CCJV shall not be first required to
enforce against TTI or any other person, any liability, obligation or duty
guaranteed hereby before seeking enforcement thereof against the undersigned.
Suit may be brought and maintained against the undersigned by CCJV to enforce
any liability, obligation or duty guaranteed hereby without joinder of TTI or
any other person. The liability of the undersigned shall not be affected by any
indulgence, compromise, settlement or variation of terms which may be extended
to TTI by CCJV or agreed upon by CCJV and TTI, and shall not be affected by any
termination of and of the Agreements, to the extent that TTI thereafter
continues to be liable thereunder. CCJV and TTI, without notice to or consent by
the undersigned, may at any time or times enter into such modifications,
extensions, amendments, or other covenants respecting the Agreements, as they
may deem appropriate and the undersigned shall not be released thereby, but
shall continue to be fully liable for the payment and performance of all
liabilities, obligations and duties of TTI under the Agreements, as so further
modified, extended or amended; PROVIDED, HOWEVER, that the undersigned shall not
be bound by any modifications, extensions, amendments, or any other covenants
respecting the Agreements prior to CCJV's notice to the undersigned of same, and
upon notice to the undersigned of the foregoing, the undersigned shall be bound
by and liable to CCJV under the terms thereof. Notice to the undersigned shall
be sufficient, if sent to Sonus Networks, Inc., 5 Carlisle Road, Westford,
Massachusetts 01886; Attention: Chief Financial Officer.

     This agreement shall be binding upon the undersigned and the successors,
heirs, executors, and administrators of the undersigned, and shall inure to the
benefit of CCJV and its heirs, executors, administrators and assigns.

                             EXHIBIT "G" Page 1 of 2
<Page>

     EXECUTED this 5th day of March, 2002.

                             Guarantor:

                             Sonus Networks, Inc.,
                                a Delaware corporation

                             By:     /s/ Peter S. Hemme
                                     ------------------------
                             Name:   Peter S. Hemme
                                     ------------------------
                             Title:  Vice President and Controller
                                     -----------------------------

                             EXHIBIT "G" Page 2 of 2
<Page>

                                   EXHIBIT "H"

                     [CONSENT BY LENDER TO TRLP TERMINATION]

                                 March 5, 2002

James Reynolds
Texas Capital Bank, National Association
2100 McKinney Ave., Suite 900
Dallas, Texas 75201

RE:      Termination of Office Lease Agreement (the "Termination") by and
         between TR Lookout Partners, Ltd. ("Landlord") and telecom
         technologies, inc. ("Tenant")

Ladies and Gentlemen:

     The Termination attached hereto has been consented to by Texas Capital
Bank, National Association ("Lender"). Lender holds the first lien on the
building affected by the Termination. Please sign where indicated below to
evidence your consent in writing to the Termination.

                             Very truly yours

                             TR Lookout Partners, Ltd.,
                              a Texas limited partnership

                             By:      Thompson Realty Investment Corporation

                                      By:      /s/ W.T. Field
                                               ---------------------
                                               W.T. Field, President

                             telecom technologies, inc.,
                               a Texas corporation

                             By:    /s/ G.M. Eastep
                                    ---------------------
                              Name: G.M. Eastep
                                    ---------------------
                              Title: Vice President and Chief Operating
                                     Officer
                                    -----------------------------------

ACCEPTED AND AGREED TO:

Texas Capital Bank, National Association
By:  /s/ James R. Reynolds
     -----------------------------
Name: James R. Reynolds
         -------------------------
Title:  SVP
      ----------------------------

                             EXHIBIT "H" Page 1 of 1
<Page>

                                   EXHIBIT "I"

           [CONSENT BY LENDER TO CCJV TERMINATION AND FIFTH AMENDMENT]

                                 March 5, 2002

Principal Life Insurance Company
C/O Principal Financial Group
Des Moines, IA 50392-1360

RE:      Termination of Office Lease Agreement (the "Termination") and Fifth
         Amendment to Office Lease Agreement (the "Amendment"), both by and
         between Collins Campbell Joint Venture ("Landlord") and telecom
         technologies, inc. ("Tenant")

Ladies and Gentlemen:

     The Termination and the Amendment attached hereto have been consented to by
Principal Life Insurance Company ("Lender"). Lender holds the first lien on the
building affected by the Termination and the Amendment. Please sign where
indicated below to evidence your consent in writing to the Termination and the
Amendment.

                             Very truly yours

                             COLLINS CAMPBELL JOINT VENTURE,
                              a Texas general partnership
                             By:      Jaytex Properties, Ltd.,
                                      a Texas limited partnership
                             By:      JRS Management, Inc.

                                      By:      /s/ W.T. Field
                                               ---------------------
                                               W.T. Field, President

                             telecom technologies, inc.,
                              a Texas corporation

                             By:      /s/ G.M. Eastep
                                      -------------------
                             Name:    G.M. Eastep
                                      -------------------
                             Title:   Vice President and Chief
                                      Operating Officer
                                      ----------------------

ACCEPTED AND AGREED TO:

PRINCIPAL LIFE INSURANCE COMPANY,
 an Iowa corporation

By:  /s/ Deborah A. Reinhard
     -----------------------------
Name: Deborah A. Reinhard
     -----------------------------
Title: Senior Loan Administrator
      ----------------------------

                             EXHIBIT "I" Page 1 of 1
<Page>

                                   EXHIBIT "J"

                           LIMITED INDEMNITY AGREEMENT

     This Limited Indemnity Agreement (this "INDEMNITY") is entered into this
5th day of March, 2002, by and among Collins Campbell Joint Venture ("CCJV"),
telecom technologies, inc., a Texas corporation ("TTI"), and Sonus Networks,
Inc. ("SONUS").

     WHEREAS, CCJV entered into a certain letter agreement, dated April 4, 1997
(the "AGREEMENT"), with Hamid Ansari and Anousheh Ansari (collectively, the
"ANSARIS"), as amended by that certain letter agreement, dated November 1, 2000
(the "AMENDED AGREEMENT"), by and between the Ansaris and CCJV;

     WHEREAS, the Agreement and the Amended Agreement (collectively, the "LETTER
AGREEMENTS") provide for the payment by CCJV of a certain profit fee to the
Ansaris under certain conditions and circumstances more fully described in the
Letter Agreements, and which circumstances and conditions have not occurred as
of this date and may not occur;

     WHEREAS, TTI has consented to the terms of the Letter Agreements, but is
not obligated to make any payments under the same to the Ansaris, nor has TTI
agreed to perform any obligations under the Letter Agreements; and

     WHEREAS, CCJV, TTI, and Sonus, among others, have entered into the terms of
a certain global agreement, dated March 5, 2002, (the "GLOBAL AGREEMENT"), and
CCJV, TTI, and Sonus acknowledge and agree that the terms of the Global
Agreement shall be binding on the parties hereto;

     NOW, THEREFORE, for and in consideration of the payment in the amount of
Ten and No/100 Dollars ($10.00) and other good and valuable consideration,
including the mutual covenants and agreements between and among CCJV, TTI, and
Sonus in the Global Agreement, the receipt and sufficiency of which are hereby
acknowledged, and in further consideration of the mutual covenants and
agreements contained herein, CCJV, TTI, and Sonus hereby agree to the above
Recitals and as follows:

     1.  This Limited Indemnity Agreement shall be subject to the occurrence of
all of the events set forth in the Global Agreement in Paragraph 1 thereof.

     2.  Subject to paragraph 3 below, CCJV agrees to (i) defend Sonus and TTI
against any claims, suits or actions brought by the Ansaris (or either one of
them) against Sonus or TTI for performance of TTI's obligations, if any, in the
Letter Agreements (the "ANSARI CLAIMS"), and (ii) indemnify Sonus and TTI
against any damages, liabilities, costs and expenses (including reasonable
attorneys' fees) awarded by a court of final jurisdiction arising out of the
Ansari Claims. CCJV shall assume the defense of the Ansari Claims against Sonus
and TTI by counsel retained at CCJV's own expense.

     3.  CCJV's indemnification obligation is conditioned on Sonus' and TTI's
compliance with the following procedures: (a) Sonus and TTI will promptly notify
CCJV in writing of any claim or the commencement of any suit, action, proceeding
or threat that Sonus and TTI believe will result in costs for which TTI or Sonus
will be entitled to indemnification; (b) Sonus and TTI will tender to CCJV (and
its insurer) full authority to defend or settle any such claim; and (c) Sonus
and TTI shall cooperate in the defense of such claim. CCJV has no obligation to
indemnify Sonus and TTI in connection with any settlement made without CCJV's
written consent.

                             EXHIBIT "J" Page 1 of 2
<Page>

     IN WITNESS WHEREOF, CCJV, Sonus, and TTI have executed this Limited
Indemnity Agreement as of the date first written above.

                             TTI:

                             telecom technologies, inc.,
                               a Texas corporation

                             By:     /s/ G.M. Eastep
                                     -------------------------
                             Name:   G.M. Eastep
                                     -------------------------
                             Title:  Vice President and Chief Operating
                                     Officer
                                     -----------------------------------

                             SONUS:

                             SONUS NETWORKS, INC.,
                                a Delaware corporation

                             By:     /s/ Peter S. Hemme
                                     -------------------------
                             Name:   Peter S. Hemme
                                     -------------------------
                             Title:  Vice President and Controller
                                     ------------------------------

                             CCJV:

                             COLLINS CAMPBELL JOINT VENTURE,
                               a Texas general partnership

                             By:      Jaytex Properties, Ltd.,
                                       a Texas limited partnership

                                      By:      JRS Management, Inc.

                                               By:      /s/ W.T. Field
                                                        ----------------------
                                                        W.T. Field, President

                            EXHIBIT "J" Page 2 of 2

</TEXT>
</DOCUMENT>
