Document:

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                                                                    EXHIBIT 10.6

         CERTAIN INFORMATION IN THIS EXHIBIT HAS BEEN OMITTED AND FILED
        SEPARATELY WITH THE COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN
            REQUESTED WITH RESPECT TO THE OMITTED PORTIONS. OMITTED
                     INFORMATION HAS BEEN REPLACED BY [*].

                           GMAC COMMERCIAL FINANCE LLC
                           1290 Avenue of the Americas
                            New York, New York 10104

                     INTERFACTOR AND SUBORDINATION AGREEMENT

                                                         as of December 12, 2003

SCM TELCO FINANCE LLC
c/o Corporation Service Company
2711 Centerville Road, Suite 400
Wilmington, DE 19808

                          Re: Arbinet-thexchange, Inc.

Gentlemen:

     Reference is made to the Factoring Agreement between Arbinet-thexchange,
Inc. (the "Client") and GMAC Commercial Finance LLC (the "Senior Factor") dated
February 1, 2003 (the "Senior Factoring Agreement"; together with all related
documents and agreements executed and/or delivered in connection therewith, as
the same may now exist or may hereafter be amended, supplemented, renewed or
extended, collectively, the "Senior Factoring Agreements").

     Reference is made to the Factoring Agreement between the Client and SCM
Telco Finance LLC (the "Junior Factor') dated December 12, 2003 (the "Junior
Factoring Agreement"; together with all related documents and agreements
executed and/or delivered in connection therewith, as the same may now exist or
may hereafter be amended, supplemented, renewed or extended, collectively, the
"Junior Factoring Agreements").

     Initially capitalized terms used and not otherwise defined herein shall
have their respective meanings as set forth or as referenced in the Senior
Factoring Agreement.

     This letter sets forth the agreement between the Senior Factor and the
Junior Factor concerning, among other things, designation of the sales of the
Client which will be factored by each of them, respectively, the appointment by
Junior Factor of Senior Factor as attorney in fact to collect those Accounts
factored in part by Junior Factor and in part by Senior Factor, it being
understood and agreed that Accounts factored only by Junior Factor will be
collected only by Junior Factor, the application by the Senior Factor of
collections on Accounts and the distribution of collections on Accounts not
credit approved in whole or in part by the Senior Factor (to the extent not so
approved, the "Unapproved Accounts") by Senior Factor to Junior Factor.

     1. Senior Factor's Right of First Refusal on Credit Requests; Allocation of
Sales. Junior creditor acknowledges and agrees that:

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     (a) All of Client's requests for credit approvals or credit lines with
respect to the Client's Customers shall be submitted first to the Senior Factor
and then, to the extent that they are Unapproved Accounts, to the Junior Factor.

     (b) Senior Factor shall factor all sales of the Client, which it has credit
approved in whole or in part (to the extent so approved, "Approved Accounts")
and Junior Factor may, in its sole discretion, factor all Unapproved Accounts.

     (c) Sales to Foreign Customers factored by the Junior Factor shall not be
further factored by Junior Factor through another factor such as Factors Chain
International or International Factors Group.

     2. Collection of Accounts; Subordination of Application of Collections.
Senior Factor shall collect all Approved Accounts of Client, and shall not
collect any Unapproved Accounts. If Junior Factor elects to factor Unapproved
Accounts, Junior Factor shall have the sole right to collect such Accounts.
Senior Factor may take any action or commence any proceeding or action as may be
necessary to effect collection of Approved Accounts. In furtherance of
collection by Senior Factor of Accounts factored in part by each of Senior
Factor and Junior Factor ("Joint Accounts") and to enable Senior Factor to
assert and enforce its rights therein, Senior Factor and any person whom Senior
Factor may designate are hereby irrevocably appointed attorney in fact for the
Junior Factor, with full power to act in the place and stead of the Junior
Factor, including the right to make, present, file and vote proofs of claim
against the Client's Customers on account of any Joint Accounts and to demand,
sue for, collect and receive any and all of such monies or dividends, assets or
other payments thereon and to apply collected funds in respect thereof, first to
the payment in full of Approved Accounts and then to the Junior Factor in
payment of Unapproved Accounts. Junior Factor will (i) execute and deliver to
Senior Factor such instruments as may be required by it to collect payment of
any and all of the Unapproved Accounts, to effectuate aforesaid power of
attorney, and to effect collection of any and all instruments or other payments
which may be made any time on the Unapproved Accounts, and (ii) provide to
Senior Factor all documents in possession of Junior Factor pertaining to the
Unapproved Accounts reasonably requested by Senior Factor from time to time. In
the event Senior Factor makes a payment to the Client on an Approved Account by
reason of Senior Factor having the Credit Risk on such Account, and thereafter
Senior Factor collects more than the amount of such payment on the invoice
evidencing such Account (such excess, "Excess Proceeds"), Senior Factor shall
credit such Excess Proceeds to Client's account in accordance with the terms of
the Senior Factoring Agreement, and Senior Factor shall have no obligation to
pay such excess funds to Junior Factor, who acknowledges that it shall obtain
any such excess funds from the Client.

     3. Standstill. Junior Factor agrees that it shall not exercise any rights
nor assert any claims with respect to any Joint Accounts, nor seek to foreclose
on its security interests in any such Accounts, nor take any action or institute
any proceedings, directly or indirectly, with respect to any such Accounts
(including, but not limited to, commencing or joining with any other creditor or
creditors in commencing any bankruptcy, reorganization or insolvency case
against any Customer obligated on any such Accounts) until the earlier of (i)
receipt by Junior Factor of notice from Senior Factor that Client has
indefeasibly satisfied in full all of Client's Obligations to Senior Factor, and
(ii) (A) if Senior Factor has failed to initiate enforcement of its rights with
respect to any Joint Account within forty-five (45) days of the assignment of
such Joint Account to Senior Factor and the posting of such Joint Account to
Client's account in accordance with the Senior Factoring Agreement, or (B) if

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Client has not submitted a Payment Request (as defined in the Senior Factoring
Agreement) to Senior Factor in respect of any Joint Account in accordance with
the time periods provided in Paragraph 3(c) of the Senior Factoring Agreement
after the expiration of which such time periods Senior Factor shall have no
obligation to Client with respect to such Joint Account, then upon two (2)
business days prior written notice to Senior Factor, Junior Factor may exercise
its rights and assert any claim with respect to such Joint Account, and, at its
option, seek to foreclose on its security interests in any such Joint Account,
or take any action or institute any proceedings, directly or indirectly, with
respect to any such Joint Account.

     4. Waiver. No waiver shall be deemed to be made by Junior Factor or Senior
Factor of any of their respective rights hereunder unless the same shall be in
writing signed by either Senior Factor or Junior Factor, as the case maybe, and
each waiver, if any, shall be a waiver only with respect to the specific
instance involved and shall in no way impair the rights of Junior Factor or
Senior Factor in any other respect at any other time.

     5. Assignment; Entire Agreement.

     (a) All of the terms, covenants and conditions contained herein shall inure
to the benefit of and be binding upon the parties hereto and their successors
and assigns, as the case may be.

     (b) None of the interests in any Unapproved Accounts held by Junior Factor
may be assigned or transferred by Junior Factor or its successors and assigns
unless Senior Factor has received from the assignee a written acknowledgment
stating that it has received a copy of this Agreement and agrees to be bound by
the terms hereof.

     (c) This Agreement sets forth the entire understanding of the parties
hereto with respect to the subject matter hereof. Neither this Agreement nor any
term may be modified, altered, waived, discharged, or terminated except by an
instrument in writing executed by the party against whom such alteration,
waiver, discharge or termination is sought to be enforced.

     6. No Benefit to Third Parties. The terms and provisions of this Agreement
shall be for the sole benefit of the parties hereto and their respective
successors and assigns; no other person, firm, entity or corporation shall have
any right, benefit, priority or interest under this Agreement.

     7. Further Assurances.

     (a) Junior Factor shall execute and deliver such additional documents and
take such additional actions as shall be necessary to effectuate the provisions
and purposes of this Agreement. If requested by Senior Factor, Junior Factor
shall execute such notice filings to be filed with the Uniform Commercial Code
records in each jurisdiction where filings have been made with respect to the
Accounts, indicating the existence of this Agreement and confirming the terms
hereof.

     (b) Without limiting the generality of the foregoing, Junior Factor agrees
that each and every financing statement filed by Junior Factor claiming a
security or other interest in any assets of the Borrower shall bear a
conspicuous legend to the effect that:

     "SECURED PARTY'S RIGHTS ARE SUBJECT TO THE TERMS OF AN INTERFACTOR AND
     SUBORDINATION AGREEMENT

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     BETWEEN SECURED PARTY AND GMAC COMMERCIAL FINANCE LLC, 1290 AVENUE OF THE
     AMERICAS, NEW YORK, NEW YORK 10104."

     8. Governing Law/Consent to Jurisdiction. JUNIOR FACTOR HEREBY WAIVES TRIAL
BY JURY IN ANY ACTION OR PROCEEDING ARISING OUT OF OR IN CONNECTION WITH THIS
AGREEMENT AND FURTHER HEREBY WAIVES ANY RIGHT OF OFFSET OR RIGHT TO INTERPOSE
ANY COUNTERCLAIM IN ANY SUCH ACTION. EACH OF THE PARTIES HERETO EXPRESSLY
SUBMITS IN ADVANCE TO THE NON-EXCLUSIVE JURISDICTION OF THE SUPREME COURT,
COUNTY OF NEW YORK AND THE UNITED STATES DISTRICT COURT FOR THE SOUTHERN
DISTRICT OF NEW YORK IN ANY ACTION OR PROCEEDING RELATING TO ANY CLAIM, DISPUTE
OR OTHER MATTER PERTAINING DIRECTLY OR INDIRECTLY TO THIS AGREEMENT. THIS
AGREEMENT SHALL BE GOVERNED BY AND INTERPRETED IN ACCORDANCE WITH THE LAWS OF
THE STATE OF NEW YORK.

     9. Reserved.

     10. Notices. All notices, requests or demands required to be made or given
hereunder shall be deemed to have been duly given or made; if by hand,
immediately upon delivery; if by certified mail, return receipt requested, five
(5) days after mailing; if by overnight delivery service, one day after
dispatch; or if by telex, telecopier (fax.) or telegram, immediately upon
receipt. All notices, requests or demands shall be in writing and shall be sent
to the respective parties at the addresses set forth below (or such other
addresses as either party may designate by notice in accordance with the
provisions of this paragraph):

     To Senior Creditor:     GMAC COMMERCIAL FINANCE LLC
                             1290 Avenue of the Americas New
                             York, New York 10104
                             Attention: John Manini
                                        Vice President
                             Fax:       212 884-7317

     To Junior Creditor:     SCM TELCO FINANCE LLC
                             Corporation Service Company
                             2711 Centerville Road, Suite 400
                             Wilmington, Delaware 19808
                             Attention: Linda Ratchford
                             Fax:       302 636-5454

     To Client:              ARBINET-THEXCHANGE, INC.
                             120 Albany Street
                             Tower II, Suite 450
                             New Brunswick, New Jersey 08901
                             Attention: Office of Contract
                             Compliance
                             Fax:       732-509-9101

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     11. Insolvency. This Agreement shall be applicable both before and after
the commencement of any Insolvency Case (as hereinafter defined) by or against
the Client under the Bankruptcy Code and all converted and succeeding cases in
respect thereof. The relative rights, as provided for in this Agreement, shall
continue after the commencement of any such case on the same basis as prior to
the date of the commencement of any such case, as provided in this Agreement,
subject to any court order approving the financing of or use of cash collateral
by the Client, as debtor-in-possession. "Insolvency Case" means any insolvency
or bankruptcy case under Title 11 of the United States Code (the "Bankruptcy
Code") or any other federal or state insolvency statute, or any receivership,
liquidation, reorganization or other similar proceedings in connection
therewith, relative to the Client or its property, or in the event of any
proceedings for voluntary liquidation, dissolution or other winding up of the
Client, whether or not involving insolvency or bankruptcy, or in the event of
any assignment for the benefit of creditors of Borrower.

     12. Term. This Agreement is a continuing agreement and shall remain in
force and effect until the payment satisfaction in full of all Obligations to
Senior Factor and the termination of all the Senior Factoring Agreements, or
until Senior Factor notifies Junior Factor, in writing, of the termination of
this Agreement, whichever shall first occur; provided that, termination of this
Agreement shall not release any party of its obligations hereunder with respect
to matters arising or events occurring prior to termination.

     13. Counterparts. This Agreement may be executed in any number of
counterparts, each of which shall be deemed to be an original hereof and
admissible into evidence, and all of which together shall be deemed to be a
single instrument.

     14. Paragraph Headings. The paragraph headings contained in this Agreement
are for reference purposes only and shall not affect in any way the meaning or
interpretation of this Agreement.

     If the foregoing correctly states our understanding and agreement, kindly
sign the counterpart of this Agreement in the space provided below.

                                        GMAC COMMERCIAL FINANCE LLC

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

AGREED:

SCM TELCO FINANCE LLC

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

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                          ACKNOWLEDGMENT AND AGREEMENT

     The undersigned hereby agrees to the terms set forth in Sections 1 and 2 of
the foregoing Interfactor and Subordination Agreement between SCM TELCO FINANCE
LLC and GMAC COMMERCIAL FINANCE LLC (the "Interfactor Agreement") and agrees
that it will, together with its successors and assigns, be bound by such terms.

     The undersigned acknowledges that it does not and will not receive any
right, benefit, priority or interest under or because of the existence of the
foregoing Interfactor Agreement.

     The undersigned agrees to execute and deliver such additional documents and
take such additional action as may be necessary or desirable to effectuate the
provisions and purposes of the Interfactor Agreement.

     THE UNDERSIGNED AGREES THAT THE VALIDITY, INTERPRETATION AND EFFECT OF SUCH
INTERFACTOR AGREEMENT SHALL BE GOVERNED BY THE LAWS OF THE STATE OF NEW YORK AND
IT HEREBY IRREVOCABLY CONSENTS TO THE NON-EXCLUSIVE JURISDICTION OF THE SUPREME
COURT OF THE STATE OF NEW YORK AND THE UNITED STATES DISTRICT COURT FOR THE
SOUTHERN DISTRICT OF NEW YORK AND WAIVES TRIAL BY JURY IN ANY ACTION OR
PROCEEDING WITH RESPECT TO SUCH INTERFACTOR AGREEMENT.

                                        ARBINET-THEXCHANGE, INC.

                                        By:  /s/ Peter P. Sach
                                            ------------------------------------
                                            Peter P. Sach
                                        Title: CAO & Treasurer

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          GUARANTY AGREEMENT, dated as of December 12, 2003, between
HIGHBRIDGE/ZWIRN SPECIAL OPPORTUNITIES FUND, L.P., a Delaware limited
partnership (the "Guarantor"), and ARBINET-THEXCHANGE, INC., a Delaware
corporation (the "Company").

                              W I T N E S S E T H :

          WHEREAS, the Guarantor is the indirect owner of 90% of the issued and
outstanding limited liability company interests of SCM TELCO FINANCE LLC, a
Delaware limited liability company (the "Factor");

          WHEREAS, the Company and the Factor have entered into a Factoring
Agreement, dated as of December 12, 2003 (the "Factoring Agreement"), pursuant
to which the Factor will provide factoring services to the Company; and

          WHEREAS, to induce the Company to enter into the Factoring Agreement,
the Guarantor is entering into this Agreement and the guaranty provided for
herein.

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

          Section 1. Guaranty. The Guarantor unconditionally and irrevocably
guarantees to the Company:

          (a) the due, prompt and complete payment by the Factor of all amounts
     due under the Factoring Agreement, when and as the same shall become due
     and payable in accordance with the terms of the Factoring Agreement, and

          (b) the due, prompt and faithful performance of, and compliance with,
     all other undertakings of the Factor contained in the Factoring Agreement
     and in any other agreement or document executed by the Factor pursuant to
     the Factoring Agreement (the Factoring Agreement and other such agreements
     and documents being sometimes collectively hereinafter referred to as the
     "Operative Documents", and the amounts payable by the Factor under any of
     the Operative Documents, and all other obligations of the Factor
     thereunder, being sometimes collectively hereinafter referred to as the
     "Guaranteed Obligations").

          This guaranty is a guaranty of payment, performance and compliance and
is in no way conditioned or contingent upon any attempt to collect from or
enforce performance or compliance by the Factor or upon any other event or
condition whatsoever. If for any reason whatsoever the Factor shall fail or be
unable duly,

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punctually and fully to pay such amounts as and when the same shall become due
and payable or to perform or comply with any other Guaranteed Obligation, the
Guarantor will forthwith pay or cause to be paid such amounts to the Company
under the terms of the applicable Operative Document, in lawful money of the
United States, at the place specified in such Operative Document, or perform or
comply with such Guaranteed Obligations or cause such Guaranteed Obligations to
be performed or complied with, together with interest (in the amounts and to the
extent required of the Factor under such Operative Documents) on any amount due
and owing from the Factor. The Guarantor, promptly after demand, will reimburse
the Company for all costs and expenses of collecting such amounts or otherwise
enforcing this Agreement, including, without limitation, the fees and expenses
of counsel.

          Section 2. Representations and Warranties. The Guarantor hereby
represents and warrants as follows:

          (a) Organization, Good Standing, Etc. The Guarantor is a limited
     partnership duly organized and validly existing and in good standing under
     the laws of the State of Delaware, and has all requisite partnership power
     and authority to own and operate its properties, to carry on its business
     as now conducted and as proposed to be conducted, and to enter into and to
     carry out the terms of this Agreement.

          (b) Due Execution and Delivery; Enforceability. This Guarantee has
     been duly executed and delivered by the Guarantor and constitutes a valid
     and legally binding obligation of the Guarantor enforceable in accordance
     with its terms, except as such enforceability may be limited by bankruptcy,
     insolvency, reorganization, moratorium or similar laws affecting creditors'
     rights generally and subject to general principles of equity. The execution
     and delivery of this Guarantee by the Guarantor and the performance by the
     Guarantor of its obligations hereunder do not violate or conflict with any
     law applicable to it, any provision of its constitutive documents, any
     order or judgment of any court or other agency of government applicable to
     it or any of its assets or any contractual provision binding on or
     affecting it or any of its assets, in any manner that could reasonably be
     expected to impair its ability to perform its obligations hereunder.

          (c) Qualification. The Guarantor is duly qualified and in good
     standing as a foreign corporation authorized to do business in each
     jurisdiction (other than the jurisdiction of its establishment) in which
     the nature of its activities or the character of the properties it owns or
     leases makes such qualification necessary and in which the failure so to
     qualify would have a materially adverse effect on the Guarantor's ability
     to perform its obligations hereunder.

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          (d) Litigation, Etc. There is no action, proceeding or investigation
     pending or threatened in writing (or any basis therefor known to the
     Guarantor) which questions the validity of this Agreement. There is no
     action, proceeding or investigation pending or threatened in writing which
     might result, either in any case or in the aggregate, in any material
     adverse change in the business, operations, affairs, condition (financial
     or otherwise), properties or assets of the Guarantor, or in any liability
     on the part of the Guarantor, which would be material to the Guarantor.

          (e) Compliance with Other Instruments, Etc. The Guarantor is not in
     violation of any term of its charter documents, constituting agreements or
     by-laws, and the Guarantor is not in violation in any material respect of
     any term of any agreement or instrument to which it is a party or by which
     it is bound or any term of any applicable law, ordinance, rule or
     regulation of any governmental authority or any term of any applicable
     order, judgment or decree of any court, arbitrator or governmental
     authority, the consequences of which violation might have a materially
     adverse effect on the business, operations, affairs, condition (financial
     or otherwise), properties or assets of the Guarantor; the execution and
     delivery by the Guarantor of, and performance of the obligations of the
     Guarantor under, this Agreement will not result in any violation of or be
     in conflict with or constitute a default under any such term or result in
     the creation of (or impose any obligation on the Guarantor to create) any
     lien upon any of the properties or assets of the Guarantor pursuant to any
     such term, which violation, conflict, default or lien might have a
     materially adverse effect on the business, operations, affairs, condition
     (financial or otherwise), properties or assets of the Guarantor or upon the
     ability of the Guarantor to perform its obligations under this Agreement;
     and there is no such term which materially adversely affects or in the
     future may (so far as the Guarantor can now reasonably foresee) materially
     adversely affect the business, operations, affairs, condition (financial or
     otherwise), properties or assets of the Guarantor.

          (f) Governmental Consent. No consent, approval or authorization of, or
     declaration or filing with, any governmental authority, on the part of the
     Guarantor is required for the valid execution and delivery of this
     Agreement and the due performance of the obligations of the Guarantor under
     this Agreement.

          Section 3. Guarantor's Obligations Unconditional. The obligations of
the Guarantor under this Agreement are primary, absolute and unconditional
obligations of the Guarantor, are not subject to any counterclaim, set-off,
deduction, diminution, abatement, recoupment, suspension, deferment or defense
based upon any claim the Guarantor or any other person may have against the
Factor, the Company or any other person, and shall remain in full force and
effect without regard to, and shall not be released, discharged or in any way
affected by, any circumstance or condition whatsoever

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(whether or not the Guarantor or the Factor shall have any knowledge or notice
thereof), including, without limitation:

          (a) any amendment of or change in, or termination or waiver of, any of
     the Operative Documents;

          (b) any furnishing, acceptance or release of, or any defect in any
     security for, any of the Guaranteed Obligations;

          (c) any failure, omission or delay on the part of the Factor to
     conform or comply with any term of any of the Operative Documents or any
     other instrument or agreement referred to in paragraph (a) above;

          (d) any waiver of the payment, performance or observance of any of the
     obligations, conditions, covenants or agreements contained in any Operative
     Document, or any other waiver, consent, extension, indulgence, compromise,
     settlement, release or other action or inaction under or in respect of any
     of the Operative Documents or any other instrument or agreement referred to
     in paragraph (a) above;

          (e) any failure, omission or delay on the part of the Company to
     enforce, assert or exercise any right, power or remedy conferred on it in
     this Agreement;

          (f) any voluntary or involuntary bankruptcy, insolvency,
     reorganization, arrangement, readjustment, assignment for the benefit of
     creditors, composition, receivership, conservatorship, custodianship,
     liquidation, marshalling of assets and liabilities or similar proceedings
     with respect to the Factor or any other person or any of their respective
     properties or creditors, or any action taken by any trustee or receiver or
     by any court in any such proceeding;

          (g) any limitation on the liability or obligations of the Factor or
     any other person under any of the Operative Documents, or any discharge,
     termination, cancellation, frustration, irregularity, invalidity or
     unenforceability, in whole or in part, of any of the Operative Documents or
     any other agreement or instrument referred to in paragraph (a) above or any
     term hereof;

          (h) any merger or consolidation of the Factor or the Guarantor into or
     with any other corporation, or any sale, lease or transfer of any of the
     assets of the Factor or the Guarantor to any other person;

          (i) any change in the ownership of any limited liability company
     interests of the Factor, or any change in the equity ownership of the
     Factor, or any termination of such ownership; or

<PAGE>

          (j) any other occurrence, circumstance, happening or event whatsoever,
     whether similar or dissimilar to the foregoing, whether foreseen or
     unforeseen, and any other circumstance which might otherwise constitute a
     legal or equitable defense or discharge of the liabilities of a guarantor
     or surety or which might otherwise limit recourse against the Guarantor,

          Section 4. Full Recourse Obligations. The obligations of the Guarantor
set forth herein constitute the full recourse obligations of the Guarantor
enforceable against it to the full extent of all of its assets and properties.

          Section 5. Waiver. The Guarantor unconditionally waives, to the extent
permitted by applicable law, (a) notice of any of the matters referred to in
Section 3, (b) notice to the Guarantor of the incurrence of any of the
Guaranteed Obligations, notice to the Guarantor or the Factor of any breach or
default by the Factor with respect to any of the Guaranteed Obligations or any
other notice that may be required, by statute, rule of law or otherwise, to
preserve any rights of the Company against the Guarantor, (c) presentment to or
demand of payment from the Factor or the Guarantor with respect to any Purchased
Account or protest for nonpayment or dishonor, (d) any right to the enforcement,
assertion, exercise or exhaustion by the Company of any right, power, privilege
or remedy conferred in the Factoring Agreement or any other Operative Document
or otherwise, (e) any requirement of diligence on the part of the Company, (f)
any requirement to mitigate the damages resulting from any default under any
Operative Document, (g) any notice of any sale, transfer or other disposition by
the Company of any right, title to or interest in any Purchased Account or in
any other Operative Document, (h) any release of the Guarantor from its
obligations hereunder resulting from any loss by it of its rights of subrogation
hereunder and (i) any other circumstance whatsoever which might otherwise
constitute a legal or equitable discharge, release or defense of a guarantor or
surety or which might otherwise limit recourse against the Guarantor.

          Section 6. Subrogation. Upon the payment in full of all amounts
payable by the Factor under the Operative Documents, and the performance in full
of all obligations to be performed or observed by the Factor under or pursuant
to the Operative Documents, the Guarantor shall be subrogated to the rights of
the Company in respect of any payment or other obligation with respect to which
an amount has been payable by the Guarantor hereunder. The Guarantor shall not
seek to exercise any rights of subrogation, reimbursement or indemnity arising
from payments made by the Guarantor pursuant to the provisions of this Agreement
until the full and complete payment or performance and discharge of the
Guaranteed Obligations.

          Section 7. Effect of Bankruptcy Proceedings. This Guaranty shall
continue to be effective or be automatically reinstated, as the case may be, if
at any time any payment made by any person on account of any of the sums due the
Company

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pursuant to the terms of the Factoring Agreement or any other Operative Document
is rescinded or must otherwise be restored or returned by the Company upon the
insolvency, bankruptcy, dissolution, liquidation or reorganization of the Factor
or any other person, or upon or as a result of the appointment of a custodian,
receiver, trustee or other officer with similar powers with respect to the
Factor or other person or any substantial part of its property, or otherwise,
all as though such payment had not been made.

          Section 8. Term of Agreement. This Agreement and all guarantees,
covenants and agreements of the Guarantor contained herein shall continue in
full force and effect and shall not be discharged until such time as all of the
Guaranteed Obligations and other independent payment obligations of the
Guarantor under this Agreement shall be paid and performed in full and all of
the agreements of the Guarantor hereunder shall be duly paid and performed in
full.

          Section 9. Notices. All notices under the terms and provisions hereof
shall be in writing, and shall be delivered or sent by telex or telecopy or
mailed by first-class mail, postage prepaid, addressed, (a) if to the Company,
at the address set forth on Schedule 7(d) to the Factoring Agreement, or at such
other address as the Company shall from time to time designate in writing to the
Guarantor and (b) if to the Guarantor, at Highbridge/Zwim Special Opportunities
Fund, L.P., 9 W. 57th Street, 27th floor, New York, NY 10019, Attention: Ivan
Zinn, or at such other address as the Guarantor shall from time to time
designate in writing to the Company. Any notice so addressed shall be deemed to
be given when so delivered or sent or, if mailed, on the third business day
after being so mailed.

          Section 10. Amendments, etc. No amendment, alteration, modification or
waiver of any term or provision of this Agreement, nor consent to any departure
by the Guarantor therefrom, shall in any event be effective unless the same
shall be in writing and signed by the company, and then such waiver or consent
shall be effective only in the specific instance and for the specific purpose
for which given.

          Section 11. Submission to Jurisdiction. The Guarantor, for itself and
its successors and assigns, hereby irrevocably (a) agrees that any legal or
equitable action, suit or proceeding against the Guarantor arising out of or
relating to this Agreement or any transaction contemplated hereby or the subject
matter of any of the foregoing may be instituted in any state or federal court
in the State of New York, (b) waives any objection which it may now or hereafter
have to the venue of any action, suit or proceeding, (c) irrevocably submits
itself to the nonexclusive jurisdiction of any state or federal court of
competent jurisdiction in the State of New York for purposes of any such action,
suit or proceeding. The Guarantor has designated and appointed Corporation
Service Company (or any successor corporation), at its office at 1177 Avenue of
the Americas, New York, New York 10036, as its authorized agent to accept and
acknowledge on its behalf service of any and all process which may be served in
any

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such action, suit or proceeding with respect to any matter as to which it has
submitted to jurisdiction as set forth in this Section 11, and agrees that
service upon such authorized agent shall be deemed in every respect service of
process upon the Guarantor or its successors or assigns, and, to the extent
permitted by applicable law, shall be taken and held to be valid personal
service upon it. Such designation and appointment shall be irrevocable. The
Guarantor represents and warrants that Corporation Service Company has agreed to
act as such agent for service of process. The Guarantor will take all action,
including the filing of any and all documents and instruments, as may be
necessary to continue in full force and effect the designation and appointment
as such agent of Corporation Service Company or any successor corporation or
such other corporation as shall be satisfactory to the Company, so that the
Guarantor shall at all times have an agent for service of process for the above
purposes in the County of New York, State of New York, Nothing contained in this
Section 11 shall be deemed to affect the right of the Company to serve process
in any other manner permitted by law or to commence legal proceedings or
otherwise proceed against the Guarantor in any jurisdiction.

          Section 12. WAIVER OF JURY TRIAL. EACH OF THE GUARANTOR AND THE
COMPANY IRREVOCABLY AND UNCONDITIONALLY WAIVES THE RIGHT TO TRIAL BY JURY IN ANY
LEGAL OR EQUITABLE ACTION, SUIT OR PROCEEDING ARISING OUT OF OR RELATING TO THIS
AGREEMENT OR ANY OF THE OTHER OPERATIVE DOCUMENTS OR ANY TRANSACTION
CONTEMPLATED HEREBY OR THEREBY OR THE SUBJECT MATTER OF ANY OF THE FOREGOING.

          Section 13. Survival. All warranties, representations and covenants
made by the Guarantor herein or in any certificate or other instrument delivered
by it or on its behalf hereunder shall be considered to have been relied upon by
the Company and shall survive the execution and delivery of this Agreement,
regardless of any investigation made by the Company or on its behalf. All
statements in any such certificate or other instrument shall constitute
warranties and representations by the Guarantor hereunder.

          Section 14. Miscellaneous. Any provision of this Agreement which is
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction. To the extent permitted
by applicable law, the Guarantor hereby waives any provision of law that renders
any provision hereof prohibited or unenforceable in any respect. The terms of
this Agreement shall be binding upon, and inure to the benefit of, the Guarantor
and the Company and their respective successors and assigns. No term or
provision of this Agreement may be changed, waived, discharged or terminated
orally, but only by an instrument in writing signed by the Guarantor and the
Company. The section and

                                        7

<PAGE>

paragraph headings in this Agreement and the table of contents are for
convenience of reference only and shall not modify, define, expand or limit any
of the terms or provisions hereof, and all references herein to numbered
sections, unless otherwise indicated, are to sections in this Agreement. This
Agreement shall in all respects be governed by, and construed in accordance
with, the laws of the State of New York (without giving effect to its choice of
law principles), including all matters of construction, validity and
performance.

                                        8

<PAGE>

          IN WITNESS WHEREOF, the Guarantor and the Company have each caused
this Agreement to be duly executed as of the day and year first above written.

                                        HIGHBRIDGE/ZWIRN SPECIAL
                                        OPPORTUNITIES FUND, L.P.

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

                                        ARBINET-THEXCHANGE, INC.

                                        By  /s/ Peter P. Sach
                                           -------------------------------------
                                           Title: CAO & Treasurer

                                        9

<PAGE>

                                                               December 12, 2003

Silicon Valley Bank\One Newton
Executive Park 2221 Washington
Street, Suite 200 Newton,
Massachusetts 02462

          Re: Loan Arrangement with Arbinet-thexchange, Inc.

Gentlemen:

     Reference is made to a certain loan arrangement entered into by and between
ARBINET-THEXCHANGE, INC., a Delaware corporation with its principal place of
business at 120 Albany Street, New Brunswick, New Jersey 08901 (the "Borrower"),
and SILICON VALLEY BANK, a California-chartered bank, with its principal place
of business at 3003 Tasman Drive, Santa Clara, California 95054 and with a loan
production office located at One Newton Executive Park, Suite 200, 2221
Washington Street, Newton, Massachusetts 02462, doing business under the name
"Silicon Valley East" ("SVB" or the "Primary Lender"), as evidenced by, among
other documents, a certain Accounts Receivable Financing Agreement dated as of
February 3, 2003 (together with all documents executed in connection therewith
or related thereto, as amended, the "AR Agreement").

     Reference is further made to a certain loan arrangement entered into by and
between the Borrower, various other parties, and ORIX VENTURE FINANCE LLC, a
Delaware limited liability company (formerly ORIX Merchant Banking LLC,
successor in interest to ORIX USA Corporation), with its principal place of
business at 1177 Avenue of the Americas, 10th Floor, New York, New York 10036
("ORIX") (ORIX and SVB shall collectively be referred to herein as the
"Lenders"), as evidenced by a certain Loan and Security Agreement dated as of
January 31, 2002 (together with all documents executed in connection therewith
or related thereto, as amended, the "ORIX Agreement").

     Reference is further made to a certain factoring arrangement entered into
by and between the Borrower and SCM TELCO FINANCE LLC, a Delaware limited
liability company with a place of business at c/o Corporation Service Company,
2711 Centerville Road, Suite 400, Wilmington, DE 19808 ("SCM") as evidenced by,
among other documents, a certain Factoring Agreement dated as of December 12,
2003 (together with all documents executed in connection therewith or related
thereto, as amended, the "Factoring Agreement").

<PAGE>

     Whereas, SVB has been granted a perfected security interest in all assets
of the Borrower, including, without limitation, a perfected security interest
in, among other things, the Borrower's accounts; and

     Whereas, ORIX has been granted a perfected security interest in all assets
of the Borrower, including, without limitation, a perfected security interest
in, among other things, the Borrower's accounts; and

     Whereas, the Borrower has requested consent from the Lenders to enter into
the Factoring Agreement with SCM.

     Now, therefore, for good and valuable consideration, SVB. ORIX, SCM and the
Borrower hereby agree as follows:

     1. All Purchased Accounts (as defined in the Factoring Agreement in effect
on the date hereof) which are purchased by SCM pursuant to the Factoring
Agreement shall be purchased subject to and subordinate to the prior security
interest in such assets of SVB and of ORIX. No other assets of the Borrower
(other than the Purchased Accounts) are or will be purchased by, or are or will
be subject to a security interest in favor of, SCM. SCM and Borrower represent
and warrant that they have provided a true, complete and correct copy of the
Factoring Agreement to the Lenders.

     2. SCM will not exercise any rights or remedies against the Borrower's
assets except for rights with respect to Purchased Accounts specifically
permitted pursuant to the terms of this Agreement.

     3. All payments owing or due to Borrower under the Factoring Agreement
shall be made by SCM to the Primary Lender, when and if such amounts are due
from SCM to the Borrower under the Factoring Agreement, notwithstanding any
contrary instructions which may hereafter be issued by Borrower or any party
other than the Primary Lender. Without limiting the foregoing, SCM shall pay the
Primary Lender the Cash Payment (as defined in the Factoring Agreement) with
respect to each Purchased Account. Each Lender hereby represents and warrants to
SCM, on behalf of itself only, and not the other Lender, that while such Lender
is the Primary Lender, no other person or entity has or will have a right to
payment of the amounts payable hereunder superior to such Lender's rights
hereunder, and that such Lender alone will be entitled to such payments and
accordingly, each Lender, on behalf of itself only, and not the other Lender,
agrees that it shall hold SCM harmless from and against any loss or reasonable
expense incurred or sustained by SCM by reason of the assertion against SCM of
claims by parties asserting that such person or entity's entitlement to such
payments, while such Lender was the Primary Lender, was superior to that of such
Lender; provided that such Lender's liability under this indemnity agreement
shall be limited to the amount of such payments received by such Lender from
SCM. The Lenders are not hereby agreeing to

                                        2

<PAGE>

indemnify SCM for the wrongful acceptance by the other Lender of amounts
received by such other Lender from SCM.

     4. In consideration of the payment by SCM to the Primary Lender of the Cash
Payment with respect to any Purchased Account, the Lenders shall be deemed to
subordinate any security interest they may have in such Account, up to the
amount of the Cash Payment paid by SCM to the Primary Lender, but the Lenders
shall retain their senior security interest in that portion of the Purchased
Account due from the Customer of such Account as exceeds the Cash Payment paid
by SCM to the Primary Lender. The Lenders shall retain their senior security
interest in such portion of the Purchased Account, to secure any amounts which
may continue to be owed by the Borrower to the Lenders. Where SCM has paid the
Cash Payment with respect to a particular Purchased Account to the Primary
Lender, and notified the Primary Lender in writing of such payment, subsequent
collections on any such Purchased Account shall first be paid to SCM until the
aggregate amount paid to or collected by SCM shall equal the Cash Payment with
respect to the particular Account. The proceeds of any other collection of any
Account (by SCM, or the Primary Lender, in accordance with Section 6 hereof),
shall be paid first to the Lenders, in accordance with the terms of a certain
Intercreditor Agreement dated February 3, 2003 by and between the Lenders.
Nothing contained herein shall impose any liability on the Lenders to (x)
reimburse SCM for payments and collections on Accounts that are received by the
Lenders before the Lenders receive payment of the Cash Payment with respect to
any Purchased Account; or (y) reimburse SCM for payments and collections on
Accounts that are received by the Borrower, either directly or in Borrower's
bank accounts, including, without limitation, cash collateral, lockbox, or other
accounts. Nothing contained herein shall obligate the Lenders to account for
each other or make or direct any payments to SCM or Borrower on account of
monies received by the other Lender.

     5. In the event that the Lenders, in the exercise of their rights against
Borrower, take possession of the books and records of Borrower during the period
while any Purchased Accounts purchased by SCM remain outstanding, the Lenders
shall grant SCM access to such books and records for the purpose of obtaining
information necessary to collect and enforce such Accounts.

     6. During the period that any Purchased Accounts are outstanding, the
Lenders shall refrain from enforcing their security interests in any such
Accounts. SCM and Borrower agree that if the Primary Lender, following the
occurrence of an event of default under its loan arrangement with the Borrower
(while there are outstanding obligations under such loan arrangement), instructs
SCM to cease collection efforts with respect to Purchased Accounts due from a
specific Customer owing Accounts for which SCM has not theretofore paid the Cash
Payment to the Primary Lender or from all Customers owing Purchased Accounts for
which SCM has not theretofore paid the Cash Payment to the Primary Lender, SCM
shall comply with such request, and SCM and

                                        3

<PAGE>

Borrower hereby agree that SCM's Purchase Commitment (as defined in the
Factoring Agreement) on such Accounts shall be deemed terminated and the Primary
Lender may enforce its security interest in such Accounts. Borrower waives any
and all claims against the Lenders resulting from such termination.

     7. Unless and until SVB provides written notice to the contrary, SVB shall
be the Primary Lender for purposes of this agreement. Upon termination of the AR
Agreement and satisfaction in full of the Obligations (as defined therein), ORIX
shall become the Primary Lender hereunder. SCM may continue to consider SVB the
Primary Lender in the event that ORIX claims to have become the Primary Lender
but SVB disputes such claim.

     8. Unless otherwise provided hereunder, all notices or demands by any party
relating to this agreement or any other agreement entered into in connection
herewith shall be in writing and (except informal documents which may be sent by
first-class mail, postage prepaid) shall be personally delivered or sent by
certified mail, postage prepaid, return receipt requested, or by facsimile, or
by reputable overnight delivery service, to the parties hereto, at their
respective addresses or fax numbers set forth below:

          If to SVB:

          SILICON VALLEY BANK
          One Newton Executive Park, Suite 200
          2221 Washington Street
          Newton, Massachusetts 02462
          Attn: Mr. David Reich, Senior Vice President
          Fax: (617) 969-5965

          With a copy to:

          RIEMER & BRAUNSTEIN LLP
          Three Center Plaza, 6th Floor
          Boston, Massachusetts 02108
          Attn: David A. Ephraim, Esquire
          Fax: (617) 880-3456

          If to ORIX:

          ORIX VENTURE FINANCE LLC
          1177 Avenue of the Americas, 10th Floor
          New York, New York 10036
          Ref: Arbinet-thexchange, Inc.
          Fax: (212) 739-1701

                                        4

<PAGE>

          With a copy to:

          ORIX USA CORPORATION
          1177 Avenue of the Americas, 10th Floor
          New York, New York 10036
          Attn: Legal Department
          Fax: (212) 739-1701

          If to SCM:

          SCM TELCO FINANCE LLC
          c/o Corporation Service Company 2711
          Centerville Road, Suite 400
          Wilmington, Delaware 19808
          Attn: Linda Ratchford
          Fax: (302) 636-5454

          With a copy to:

          DEBEVOISE & PLIMPTON, LLP
          919 Third Avenue
          New York, New York 10022
          Attn: Deborah F. Stiles, Esq.
          Fax: (212) 909-6836

          If to the Borrower:

          ARBINET-THEXCHANGE, INC.
          120 Albany Street
          New Brunswick, NJ 08901
          Attn: Mr. Michael Lemberg
          Fax:

          With a copy to:

          ARBINET-THEXCHANGE, INC.
          120 Albany Street
          New Brunswick, NJ 08901
          Attn: Chi K. Eng, Esquire
          Fax:

     The parties hereto may change the address at which they are to receive
notices hereunder, by notice in writing in the foregoing manner given to the
other.

                                        5

<PAGE>

     This letter shall be governed by and construed in accordance with the laws
of the State of New York without regard to the conflicts of law provisions
thereof (other than Section 5-1401 of the New York General Obligations Law).

                                        6

<PAGE>

     This letter shall take effect as a sealed instrument under the laws of the
State of New York as of the date first written above.

                                        Very truly yours,

SILICON VALLEY BANK                     SCM TELCO FINANCE LLC

By:  /s/ David Reich                    By:  /s/ Daniel Zwirn
   ----------------------------------       ------------------------------------

Name: David Reich                       Name
     --------------------------------        -----------------------------------

Title: SVP                              Title
      -------------------------------         ----------------------------------

                                        ORIX VENTURE FINANCE LLC

                                        By:  /s/ Kevin P. Sheehan
                                            ------------------------------------
                                        Name: Kevin P. Sheehan
                                        Title: President & CEO

Agreed to and accepted:

ARBINET-THEXCHANGE, INC.

By:  /s/ Peter P. Sach
   -----------------------------------

Name: Peter P. Sach
     ----------------------------------

Title: CAO & Treasurer

                                        7

<PAGE>

     FACTORING AGREEMENT, dated as of December 12, 2003 (the "Effective Date"),
between SCM TELCO FINANCE LLC ("Factor") and ARBINET-THEXCHANGE, INC.
("Client").

     1.   APPOINTMENT

     Client hereby appoints Factor to act as its factor upon the terms and
conditions set forth in this Agreement.

     2.   DEFINED TERMS

     Defined terms used herein without definition shall have the respective
meanings ascribed thereto in Section 14.

     3.   COVERED SALES; SECURITY INTEREST

          (a) Client hereby assigns and sells to Factor, as absolute owner, and
Factor hereby purchases from Client, all Purchased Accounts created on or after
the Effective Date, subject to the Current Security Interests to the extent set
forth in the Interfactor Agreement and the Intercreditor Agreements (the "Senior
Security Interests"). Factor's purchase of and acquisition of title to each
Purchased Account will be effective as of the date of its generation.

          (b) Client hereby grants to Factor a security interest in all of the
Collateral as security for the performance of Client's obligations hereunder,
subject to the Senior Security interests.

     4.   CUSTOMER PURCHASE APPROVAL

          (a) Client may submit a written request (a "Credit Analysis Request")
to Factor to indicate, with respect to one or more Customers listed in Credit
Analysis Request (the "Proposed Customers") whose Accounts Client may request
Factor to purchase, the aggregate Credit Limit with respect to any Purchase
Period for each Proposed Customer (each, an "Estimated Credit Limit"). Each
Credit Analysis Request shall contain the following information:

               (i) the identity of such Proposed Customer;

               (ii) the maximum dollar amount of Accounts of such Proposed
Customer that Client wishes Factor to purchase in any Purchase Period;

               (iii) whether such Proposed Customer is a Domestic Customer or a
Foreign Customer;

               (iv) the factoring arrangements, if any, then in effect between
GMAC and such Proposed Customer; and

               (v) such other information reasonably requested by Factor to
analyze the creditworthiness of such Proposed Customer.

          (b) Not later than the seventh business day following delivery of any
Credit Analysis Request, Factor will provide to Client a non-binding estimate of
the Estimated Credit Limit (which may be zero) for each Proposed Customer listed
in such Credit Analysis Request.

          (c) Not later than five business days prior to the commencement of any
Purchase Period, Client may request that Factor purchase all or a portion of the
Accounts (the "Requested

<PAGE>

Accounts") of any Proposed Customer with respect to such Purchase Period by
submitting a written request (a "Purchase Request"*) to Factor containing the
following information:

               (i) the identity of such Proposed Customer;

               (ii) the maximum dollar amount of Accounts of such Proposed
Customer that Client wishes Factor to purchase in such Purchase Period;

               (iii) whether such Proposed Customer is a Domestic Customer or a
Foreign Customer; and

               (iv) the factoring arrangements, if any, then in effect between
GMAC and such Proposed Customer.

          (d) Such Purchase Request may be in the form of a spreadsheet and may
include all information relating to Requested Accounts in one file.

          (e) Factor may in its sole discretion agree to purchase all or a
portion of the Requested Accounts of any Proposed Customer for any Purchase
Period. Factor will provide Client with written confirmation of which Requested
Accounts, if any, will be purchased for the applicable Purchase Period (a
'"Purchase Commitment"). The Purchase Commitment will include the maximum dollar
amount Factor will purchase with respect to each Proposed Customer for such
Purchase Period (each, a "Credit Limit") and such other terms as will be agreed
to by Factor and Client. If Factor does not provide a written response declining
any of the Requested Accounts three business days prior to the start of the
applicable Purchase Period, such Requested Accounts shall be deemed approved by
Factor pursuant to a Purchase Commitment.

          (f) If Client receives a Purchase Commitment with respect to the
Requested Accounts of any Customer and does not submit to Factor a new Purchase
Request for such Customer's Requested Accounts in a subsequent Purchase Period,
then the Purchase Commitment for such Customer's Requested Accounts shall remain
in effect for successive consecutive Purchase Period, unless otherwise
terminated or reduced pursuant to Section 4(g).

          (g) Factor may at any time terminate any Purchase Commitment or reduce
the Credit Limit with respect to any Customer in Factor's sole discretion,
provided that (i) no Credit Limit may be reduced below an amount equal to the
sum of (x) the undrawn amount of unexpired letters of credit issued for the
account of such Customer, so long as the issuer, form and substance of the
letter of credit are acceptable to Factor and have been issued to Factor as
beneficiary or to Client as beneficiary subject of an assignment of proceeds in
favor of Factor (with the comment of the Issuer) that are acceptable to Factor
as to form and substance and (y) the amount, if any, of cash deposited with
Factor to secure any Customer's obligations pursuant to cash collateral
agreements acceptable to Factor as to form and substance and (ii) a Purchase
Commitment with respect to a Customer shall be deemed automatically cancelled
upon the occurrence of an Insolvency Event with respect to such Customer. If
Factor cancels or is deemed to have cancelled a Purchase Commitment in respect
of a Customer, then Factor shall have no further obligations with respect to any
Accounts generated after the date of such cancellation by Factor and if Factor
reduces the Credit Limit in respect of any Customer, the Purchased Accounts of
such Customer after such reduction shall be subject to such Credit Limit, as so
reduced.

          (h) In the event either Client or Factor obtains knowledge of any
Insolvency Event with respect to any Customer whose Accounts have been purchased
hereunder, it shall immediately provide notice thereof to the other party
hereto.

                                        2

<PAGE>

          (i) Client shall immediately provide notice to Factor regarding any
change in the factoring arrangements between GMAC and Client with respect to any
Account that is a Joint Account.

     5.   PURCHASE PRICE OF PURCHASED ACCOUNTS; PAYMENT REQUEST

          (a) The purchase price of each Purchased Account shall be the Gross
Face Amount thereof (regardless of any computational or other error of Client
with respect thereto), as adjusted pursuant to Section 5(b) (the "Purchase
Price").

          (b) The Purchase Price of each Purchased Account shall be paid in cash
by Factor only to the extent required by Section 5(c). Factor's obligation to
pay the Purchase Price of any Purchased Account shall be reduced if and to the
extent (i) that Client receives payment in respect of such Purchased Account
from the applicable Customer, (ii) that such Customer fails to pay such Purchase
Price within 75 days after the original due date of such Customer's Purchased
Account for any reason other than an Insolvency Event, (iii) of the Purchase
Price Discount provided for in Section 5(d) or (iv) any portion of such Purchase
Price is the subject of a Dispute, provided that if such Dispute is finally
                                   --------
settled in accordance with Section 9(e) of the Trading Terms, the Purchase Price
of such Purchased Account shall be increased by the dollar amount of the
settlement of such Dispute.

          (c) If any Purchased Account of any Customer remains wholly unpaid for
75 days or more after the original due date of such Purchased Account solely on
account of an Insolvency Event with respect to such Customer, Client may deliver
to Factor a Payment Request not later than 90 days after the original invoice
date of such Purchased Account. Upon receipt of any such Payment Request, Factor
shall pay to Client on the Settlement Date an amount equal to 95% of the
Purchase Price (the "Cash Payment") for each Purchased Account as to which
Client has submitted a Payment Request. Without limitation of any of Factor's
rights set forth herein and notwithstanding anything to the contrary set forth
herein, Factor shall have no obligation to pay to Client the Purchase Price of
any Purchased Account as to which a Payment Request has been submitted if (i)
Client shall not have delivered to Factor following the delivery by Factor to
Client of a written request therefor, (x) within 10 business days, all Credit
Loss Documentation with respect to such Purchased Account, (y) within 20
business days, all applicable Customer Orders with respect to such Purchased
Account or (z) within 10 business days, reasonable evidence satisfactory to
Factor that Client's title to such Purchased Account and all other payment
obligations, however arising, due to Client from such Customer with respect to
such Purchased Account, are free and clear of all Liens other than Permitted
Liens, provided that if Factor believes Client has not delivered to Factor all
of the information required to be delivered pursuant to this clause (i) within
the period set forth above in clauses (x), (y) or (z), as applicable, SCM will
provide notice to Client specifying the outstanding information and Client shall
have five business days from its receipt of such notice to provide such
outstanding information, (ii) Client shall have made any change to the terms of
such Purchased Account without Factor's prior written consent or (iii) if Client
shall be in breach of any material representation, warranty or covenant
hereunder.

          (d) Upon payment of the Purchase Price of any Purchased Account of any
Customer pursuant to Section 5(c), Factor shall collect such Purchased Account
directly from such Customer, subject the provisions of the Interfactor
Agreement. Client agrees that, in the event that Factor recovers all or any
portion of the Purchase Price of any Paid Account from a Customer, the proceeds
thereof shall be applied first, to pay, or reimburse Factor for the payment of,
any reasonable expenses of collecting such Purchase Price; second, to reimburse
Factor for the Cash Payment paid by Factor pursuant to Section 5(c); and third,
to pay Client the Purchase Price Discount.

                                        3

<PAGE>

     6.   FEES

          (a) Client shall pay to Factor the following fees (collectively the
"Fees") in respect of Factor's services hereunder:

               (i) as a utilization fee (the "Utilization Fee"), on or prior to
the fifth business day following the end of each Purchase Period, the sum of the
products of (x) [*]% times (y) the Gross Face Amount of each Purchased Account
purchased during such Purchase Period (the "Purchased Account Gross Amounts");

               (ii) as a commitment fee (the "Unused Line Fee"), on or prior to
the fifth business day following the end of each Purchase Period, the sum of the
products of (x) [*]% times (y) the difference between (A) the Monthly Credit
Limit of each Customer and (B) the Purchased Account Gross Amount of such
Customer with respect to such Purchase Period;

               (iii) as a monitoring fee (the "Monitoring Fee"), on or prior to
the fifth business day following the end of each Purchase Period, the sum of the
products of (x) [*]% times (y) the Monthly Credit Limit of each Customer;

               (iv) on or prior to the fifth business day following the end of
each calendar quarter (other than the calendar quarter in which the Effective
Date falls (the "First Quarter"') and the calendar quarter immediately following
the First Quarter (the "Second Quarter"), the difference between (x) the sum of
the Minimum Quarterly Fees for such quarter and each preceding quarter in the
applicable calendar year and (y) the sum of (A) the aggregate Utilization Fees,
Unused Line Fees and Monitoring Fees paid in respect of the Purchase Periods
during such quarter and each preceding quarter in the applicable calendar year
plus (B) the aggregate Minimum Quarterly Fees paid in respect of each such
preceding quarter in the applicable calendar year; and

               (v) on the Effective Date, as a prepaid Minimum Quarterly Fee for
(x) the period from the Effective Date through the last day of the First Quarter
and (y) the Second Quarter, an amount equal to (A) for the First Quarter, the
product of (1) the Minimum Quarterly Fee for such quarter times (2) a fraction,
the numerator of which is the number of days in the First Quarter on and after
the Effective Date and the denominator of which is the number of days in the
First Quarter and (B) for the Second Quarter, the Minimum Quarterly Fee for such
quarter. For the last calendar quarter during the Term (the "Last Quarter"), the
Minimum Quarterly Fee shall be the product of (1) the Minimum Quarterly Fee for
such quarter times (2) a fraction, the numerator of which is the number of days
in the Last Quarter to and including the last day of the Term and the
denominator of which is the number of days in the Last Quarter.

          (b) The fees payable pursuant to Section 6(a) shall be paid by wire
transfer to Account No. 2090067 of Factor at LaSalle Bank N.A. - Chicago, ABA
071000505. Factor must provide Client with written notification at least five
business days prior to changing the details for any wire transfer.

          (c) In the event Client shall fail to pay any portion of a fee arising
under this Article 6 when due (any such portion, an "Unpaid Fee"). Client shall
pay a Late Fee with respect to such Unpaid Fee.

     7.   REPRESENTATIONS, WARRANTIES AND COVENANTS

     Client hereby represents, warrants and covenants that:

          (a)  As of each day on which an Account is purchased hereunder, (i)
               Client has good title to such Purchased Account, free of and
               clear of all Liens other than Permitted Liens, (ii) each such

                                        4

<PAGE>

Purchased Account is a bona fide, enforceable obligation arising in the ordinary
course of business of Client, (iii) the applicable Customer is unconditionally
obligated to pay at maturity the full amount of such Purchased Account relating
to it without defense, counterclaim or offset other than offsets permitted
pursuant to the Trading Terms and (iv) all documents evidencing such Customer's
payment obligations with respect to such Purchased Account are in full force and
effect.

          (b) Client's exact legal name is as set forth on the signature page of
this Agreement. Client will provide Factor with written notice within 30
business days of changing its legal name.

          (c) Client is an organization of the type and organized in the
jurisdiction set forth on Schedule 7(c). Schedule 7(c) accurately sets forth
Client's organizational identification number or accurately states that Client
has none and accurately sets forth Client's federal employer identification
number. Client will provide Factor with written notice within 30 business days
of changing its organizational identification number or changing its type of
organization. Client shall not change its jurisdiction, of organization unless
Factor shall have received not less than 30 business days' prior written notice
of such proposed change.

          (d) Client's chief executive office and mailing address and Client's
Records concerning Accounts are located only at the address identified as such
on Schedule 7(d). Client shall not change its chief executive office or mailing
address unless Factor shall have received not less than 30 business days' prior
written notice of such proposed change.

          (e) Client shall furnish to Factor (i) within five business days after
the last business day of each Purchase Period, a detailed sales register and a
detailed aged trial balance that includes all Purchased Accounts as of the end
of such Purchase Period, certified by Client's Chief Executive Officer, Chief
Financial Officer, Chief Administrative Officer, Vice President of Finance, Vice
President of Business Planning and Treasury Operations or Vice President of
Business Systems and (ii) within 120 days after the end of Client's fiscal year,
an audited financial statement with respect to such fiscal year, certified by
Client's Chief Executive Officer, Chief Financial Officer or Chief
Administrative Officer and reviewed by Ernst & Young or another independent
certified public accountant acceptable to Factor, such acceptance to be provided
by Factor prior to the accountant's undertaking its annual audit. Client shall,
at Client's expense, furnish Factor with other financial and operational
information reasonably requested by Factor from time to time. Upon reasonable
notice, Factor shall have full access to and the right to audit, check, inspect
and make abstracts and copies from Client's Records, audits, correspondence and
all other papers relating to the Purchased Accounts and the operation of
Client's business. Factor and its agents may enter upon Client's premises at any
time and from time to time, during business hours upon reasonable notice, for
the purpose of inspecting any and all Records pertaining to the Purchased
Accounts and to the operation of Client's business. On the first day of each
month following any month in which Factor has performed any collection audit or
field examination, Client shall pay to Factor a fee equal to Factor's then
effective standard rate per day, per person employed or retained by Factor to
perform such audits and field examinations, it being acknowledged that as of the
Effective Date, Factor's standard rate is $1,500 per day, per person, plus all
reasonable costs, fees and expenses incurred by Factor or its representatives in
the performance of such audits and field examinations, provided that Client
shall be required to pay the foregoing fee for no more than two persons per
audit or field examination. Factor agrees that until the second anniversary of
the Effective Date Factor's standard rate per day, per person, shall remain
$1,500. So long as Client is not in breach of this Agreement, Factor shall
conduct no more than one collection audit of Client's Records during any
calendar year. All information provided to Factor shall be governed by the
Non-Disclosure Agreement, dated as of November 15, 2003, between Factor and
Client.

          (f) Client shall, within fifteen business days after a Dispute with
respect to an amount greater than $100,000 related to a Purchased Account is
asserted, notify Factor of the assertion and provide Factor copies of all
communications between Client and the applicable Customer with regard to such
Dispute, Client will settle all Disputes at no cost or expense to Factor.

          (g) Client is and shall remain in compliance with all laws,
regulations and rules applicable to Client's business, including all laws, rules
and regulations of the United States and state and local governmental entities
relating to telecommunications services and all laws, rules and regulations of
foreign jurisdictions in which Client has a physical presence, including but not
limited to personnel, real estate and equipment, whether leased or owned, except
to the extent that the failure to comply therewith is not reasonably likely,
alone or in the aggregate, to have a material adverse effect on the business,
operations or condition (financial or otherwise) of Client.

          (h) Client shall take all other reasonable actions requested by Factor
from time to time to cause the attachment, perfection and priority of, and
Factor's ability to enforce, Factor's security interest in any and all of the
Collateral, subject only to the prior security interest of the Lenders and GMAC.
Client irrevocably and unconditionally authorizes Factor (or Factor's agent) to
file and ratifies the

<PAGE>

filing at any time and from time to time of such financing statements with
respect to the Collateral naming Factor or Factor's designee as the secured
party and Client as debtor, as Factor may require, and including any other
information with respect to Client or otherwise required by Article 9 of the
Uniform Commercial Code of such jurisdictions as Factor may determine, together
with any amendment and continuation statements with respect thereto, which
authorization shall apply to all financing statements filed on, prior to or
after the date hereof. In no event shall Client at any time file, or permit or
cause to be filed, any amendment or termination statement with respect to any
financing statement (or amendment or continuation statement with respect
thereto) naming Factor or Factor's designee as secured party and Client as
debtor.

          (i) Upon Factor's reasonable request, Client shall, at Client's
expense, duly execute and deliver, or cause to be duly executed and delivered,
to Factor such further instruments and do and cause to be done such further acts
as may be necessary or proper in the opinion of Factor to effectuate the
provisions and purposes of this Agreement.

     8.   INVOICES; CREDIT INFORMATION REQUESTS

          (a) With respect to each Trading Account Invoice of Client evidencing
Purchased Accounts due from Customers, at Factor's option, Client shall either
(i) furnish Factor with a legible duplicate of the original invoice or (ii) make
such invoice available for the Factor to view on thexchange website. Client
shall at the end of each Purchase Period furnish to Factor evidence satisfactory
to Factor of each rendition of services by Client to Customers in respect of the
Purchased Accounts. Client agrees that Factor shall not be liable for any
selling expenses, orders, purchases or contracts of any kind resulting from any
of Client's transactions and Client shall indemnify Factor and hold Factor
harmless with respect thereto. Other than Value Added Tax in the United Kingdom,
Client represents and warrants to Factor that there are no taxes payable as a
result of Customers' purchases of telecommunications network capacity and that
Client will at all times promptly pay such taxes when due and file all tax
returns relating to such taxes in a timely manner.

          (b) Factor may at any time request Client to provide detailed credit
information with respect to any Purchased Account or Customer, and Client shall
provide all such requested information to Factor within five business days of
receiving any such request.

     9.   EXCLUSIVITY

          (a)  Except for Client's factoring arrangements with GMAC, any
               factoring arrangements entered into pursuant to current
               discussions between Client and Marsh USA, Inc. ("Marsh")

                                        6

<PAGE>

regarding potential factoring arrangements, and Client's financing arrangements
with the Lenders, Factor shall be the exclusive provider of factoring services
to Client during the Term (i) in the United States so long as the rate payable
by each Customer under its Customer Agreement in respect of its utilization fees
for any Billing Period is at least [*] and (ii) in any other country so long
as (x) Factor is legally able to provide such services in such country and (y)
the rate payable by each Customer under its Customer Agreement in respect of its
utilization fees for any Billing Period is at least [*].

          (b) Except for Client's factoring arrangements with GMAC, Client shall
not solicit or enter into any agreement on the same terms or in competition
with, this Agreement during the term of this Agreement, without the prior
written consent of Factor.

     10.  RIGHT OF FIRST REFUSAL

     In the event that:

          (a) the GMAC Agreement shall have been terminated;

          (b) the GMAC Agreement shall have been amended or modified so that the
factoring obligations of GMAC thereunder have been reduced; or

          (c) GMAC or any other GMAC Factor shall withhold or withdraw credit
approval for any Customers of Client;

Client shall not accept any offer (an "Offer") from any person other than Factor
or Marsh to provide factoring services substantially similar to the services
provided by GMAC under the GMAC Agreement in any country in which Factor is
legally able to provide such services without first giving written notice of
such offer (the "Offer Notice") to Factor, identifying the proposed provider of
services and specifying the fees and other terms and conditions of the Offer,
Client agrees that if Factor delivers a written notice to Client within 30
business days after receipt of the Offer Notice agreeing to provide Client the
services described in the Offer Notice on terms and conditions substantially
similar to the terms and conditions of the Offer (including the fees specified
therein). Factor shall have the right to provide such services on such terms and
conditions unless Client's Board of Directors does not approve Factor's
proposal.

     11.  TERMINATION

     This Agreement shall remain in full force and effect during the period from
the Effective Date to and including the second anniversary of the Effective Date
(the "Term"), unless sooner terminated as follows:

          (a) Either party may terminate this Agreement at any time upon 60
business days' prior written notice to the other party, provided that if Client
gives such notice prior to the first anniversary of the Effective Date, Client
shall pay Factor a termination fee of $250,000 upon the termination of this
Agreement.

          (b) Either party hereto may terminate this Agreement immediately,
without notice to the other party, and, in the case of termination by Client
pursuant to this clause (b), without payment of the fee described in clause (a),
if the other party shall suspend business, sell all or a significant portion of
its assets, become insolvent, make an assignment for the benefit of creditors,
or apply for an extension from creditors; or if a meeting of its creditors is
called; or if a receiver or trustee shall be appointed for it or its property;
or if its property shall become subject to any Lien or attachment except
attachments that are bonded or discharged within 30 business days after they
first arise; or if a Bankruptcy Case shall be filed by or against it; or if the
other party shall seek relief under any insolvency statute, federal, state or
other; or if a custodian shall be appointed for all or substantially all of its
property; or if the other party shall breach this

                                        7

<PAGE>

Agreement or any other agreement between Factor and Client or between Client and
any affiliate of Factor; or if the other party shall fail to pay any obligation
when due hereunder or if ownership or control of 50% or more of the other
party's aggregate outstanding stock, stock equivalents or any other equity
changes after the Effective Date.

     12.  PLACE OF PAYMENT; NEW YORK LAW, FORUM SELECTION; WAIVER OF JURY TRIAL

          (a) This Agreement shall be governed by and construed according to the
laws of the State of New York (without giving effect to its choice of law
principles).

          (b) Client agrees that (i) all actions and proceedings arising out of
or relating directly or indirectly to this Agreement or any ancillary agreement
shall be litigated in the United States District Court for the Southern District
of New York or, at Factor's option, in any other courts located in New York or
elsewhere as Factor may select, (ii) such courts are convenient forums, and
(iii) it shall submit to the personal jurisdiction of such courts. Client hereby
consents to the service of process therein by registered or certified mail,
return receipt requested, directed to Client at Client's address set forth below
its name on the signature page hereof, and Client agrees that service so made
shall be deemed complete five business days after the date of mailing.

          (c) TO THE EXTENT LEGALLY PERMISSIBLE, EACH OF CLIENT AND FACTOR WAIVE
ALL RIGHT TO TRIAL BY JURY IN ANY LITIGATION RELATING TO THIS AGREEMENT, WHETHER
SOUNDING IN CONTRACT, TORT OR OTHERWISE.

     13.  REMEDIES; WAIVERS

          (a) Factor's rights and remedies under this Agreement will be
cumulative and not exclusive of any other right or remedy Factor may have under
the UCC or otherwise.

          (b) Factor shall have the right, in Factor's sole discretion, to
determine any rights or remedies Factor may at any time pursue or to take any
other action and incur any costs or expenses with respect thereto and such
determination will not in any way modify or affect any of Factor's rights
hereunder. Failure by Factor to exercise any right, remedy or option under this
Agreement or any delay by Factor in exercising the same will not operate as a
waiver and no waiver by Factor will be effective unless set forth in a signed
writing and then only to the extent specifically stated.

     14.  DEFINITIONS

     As used herein:

          "Accounts" shall mean, with respect to any Customer and any time
period, all of Client's present and future rights to payment that are due from
such Customer in respect of the net purchase of telecommunications traffic
through Client during such time period pursuant to a Customer Agreement.

          "Bankruptcy Case" shall mean a case or proceeding under the United
States Bankruptcy Code.

          "Billing Period" shall mean, with respect to any calendar month, each
of the period from the Is1 through the 15th days of such month and the period
From the 16th through the last day of such month.

          "Cash Payment" shall have the meaning set forth in Section 5(c).

                                        8

<PAGE>

          "Collateral" shall mean and include ail Purchased Accounts and all
proceeds and products of the Purchased Accounts.

          "Credit Limit" shall have the meaning set forth in Section 4(e).

          "Credit Loss Documentation" shall mean, with respect to each Purchased
Account for which Client has submitted a Payment Request to Factor, each and all
of the following, in form and substance acceptable to Factor in its reasonable
discretion: (a) Factor's credit approval number, if any, with respect to each
such Purchased Account; (b) the Trading Account Invoice with respect to such
Purchased Account and any trading account statements accompanying such Trading
Account Invoice, (c) written evidence of the occurrence of an Insolvency Event
with respect to such Customer, (d) all correspondence relating to such Purchased
Account and Client's original collection file with respect to such Customer and
(e) such additional documentation relating to each such Purchased Account as
Factor may from time to time reasonably request of Client.

          "Current Security Interests" shall mean the security interests with
respect to the Purchased Accounts granted by Client to or for the benefit of
GMAC, Silicon and Orix pursuant to the GMAC Agreement and the Intercreditor
Agreements, respectively.

          "Customer" shall mean any person who is a "Member" of Client (as
defined in the Trading Terms).

          "Customer Agreement" shall mean, with respect to any Customer, the
Member Application entered into by such Customer with Client, including the
Trading Terms, substantially in the form attached hereto as Annex A.

          "Customer Orders" shall mean with respect to each Purchased Account
for which Client has submitted a Payment Request, the applicable Customer Buy
Orders and Sell Orders with respect to the Billing Period covered by the Trading
Account Invoice with respect to such Purchased Account.

          "Daily Credit Limit" shall mean, with respect to any Customer and any
day in a Purchase Period, the Credit Limit of such Customer in effect on such
day.

          "Dispute" shall mean any dispute between Client and any Customer
relating to any Trading Account Invoice pursuant to Section 9(c) of the Trading
Terms.

          "Domestic Customer" shall mean a Customer organized under the laws of
a state of the United States or Canada and the principal place of business of
which is located in the United States or Canada.

          "Effective Date" shall mean the date set forth in the introductory
paragraph hereto.

          "Financing Agreements" shall mean (a) the Accounts Receivable
Financing Agreement, dated as of February 3, 2002, between Silicon and Client,
and (b) the Loan and Security Agreement, dated as of January 31, 2002, among
Client, Orix and various other parties, in each case as amended from time to
time.

          "Foreign Customer" shall mean a Customer organized under the laws of a
country other than the United States or Canada and the principal place of
business of which is located in a country other than the United States or
Canada.

          "GMAC" shall mean GMAC Commercial Finance LLC.

                                        9

<PAGE>

          "GMAC Agreement" shall mean the Factoring Agreement, dated as of
February 10, 2003, between GMAC and Client, as amended from time to time.

          "GMAC Factor" shall mean GMAC or any affiliate thereof which provides
factoring services to Client or extends credit to Client secured by Accounts.

          "Gross Face Amount" shall mean with respect to any Purchased Account
of any Customer for any Billing Period (a) that is not a Joint Account, the
amount due to Client from such Customer for purchased telecommunications network
capacity utilized during such Billing Period, net of amounts due to such
Customer from Client for telecommunications network capacity sold by such
Customer through Client and utilized during the same Billing Period, in each
case as shown on the Trading Account Invoice with respect to such Billing Period
(the "Utilized Amount") or (b) that is a Joint Account, the excess, if any, of
(i) the Utilized Amount over (ii) the maximum aggregate dollar amount of ail
credit extended by GMAC with respect to the Purchased Accounts of such Customer
for such Billing Period, provided that in no event shall the Gross Face Amount
of any Purchased Account, when aggregated with the Gross Face Amounts of all
other Purchased Accounts of such Customer with respect to the Purchase Period in
which such Purchased Account is purchased, exceed the Credit Limit for such
Customer with respect to such period.

          "Insolvency Event" shall mean, with respect to any Customer, (a) the
commencement of a Bankruptcy Case by or against such Customer, (b) the
commencement of insolvency proceedings by or against such Customer under any
other law or (c) the appointment of a trustee, receiver or custodian with
respect to all or substantially all of the property of such Customer.

          "Interfactor Agreement" shall mean the Interfactor and Subordination
Agreement, dated on or about December 12, 2003, between Factor and GMAC.

          "Intercreditor Agreements" shall mean (a) the letter agreement, dated
as of February 3, 2003, among GMAC, Orix and Silicon and (b) the letter
agreement, dated on. or about December 12, 2003 among Factor, Client, Orix and
Silicon.

          "Interest Rate" shall mean 1.00% per month.

          "Joint Account" shall mean an Account that is being factored in part
by each of Factor and GMAC.

          "Late Fee" shall mean, with respect to any period and any Unpaid Fee,
the product of: (a) the Interest Rate, (b) such Unpaid Fee and (c) a fraction,
the numerator of which is the number of days from and including the day on which
such Unpaid Fee is due to and excluding the day on which such Unpaid Fee is paid
and the denominator of which is 30.

          "Lender" shall mean each of Silicon, Orix and any other lender to
Client approved by Factor.

          "Lien" shall mean, as applied to any property, real or personal,
tangible or intangible, any pledge, mortgage, lien, charge, security interest or
encumbrance of any kind thereon (including any conditional sale or other title
retention agreement, any lease in the nature thereof or the interest of the
lessor under any capitalized lease).

          "Minimum Quarterly Fee" shall mean (a) $100,000, with respect to any
calendar quarter-in which Factor has agreed to purchase Accounts of Customers
located only in the United States and the United Kingdom and (b) $150,000, with
respect to any calendar quarter in which Factor has agreed to purchase Accounts
of Customers located in the United States and the United Kingdom and at least $5

                                       10

<PAGE>

million of Accounts of Customers located in four additional jurisdictions
selected by Client and agreed to by Factor.

          "Monthly Credit Limit" shall mean, with respect to any Customer and
any Purchase Period, the sum of the Daily Credit Limits of such Customer for
each day in such Purchase Period, divided by the number of days in such Purchase
Period.

          "ORIX" shall mean Orix Merchant Banking LLC.

          "Paid Account" shall mean any Purchased Account as to which Factor has
made a Cash Payment to Client pursuant to Section 5(c).

          "Payment Request" shall mean, as to any Purchased Account, Client's
written request for payment by Factor to Client of any remaining outstanding
balance of the Purchase Price thereof.

          "Permitted Lien" shall mean any Lien with respect to a Purchased
Account in favor of Factor, any Lender or GMAC.

          "Purchase Commitment" shall have the meaning set forth in Section
4(e).

          "Purchase Period" shall mean the two Billing Periods within any
calendar month.

          "Purchase Price" shall have the meaning set forth in Section 5(a).

          "Purchase Price Discount" shall mean, with respect to any Paid
Account, the difference between the Purchase Price thereof and the Cash Payment
with respect thereto.

          "Purchase Request" shall have the meaning set forth in Section 4(c).

          "Purchased Account" shall mean, with respect to any Customer and any
Billing Period, an Account that (a) has been approved by Factor pursuant to
Section 4(e) pursuant to a Purchase Commitment, (b) is created during such
Billing Period, (c) is evidenced by a Trading Account Invoice with respect to
such Billing Period and (d) the dollar amount of which, together with all other
Purchased Accounts of such Customer with respect to the Purchase Period in which
such Purchased Account is purchased, does not exceed the Credit Limit of such
Customer for such Purchase Period.

          "Records" shall mean all of Client's present and future books of
account of every kind or nature, purchase and sale agreements, invoices, ledger
cards, ledger sheets, bills of lading and other shipping evidence, statements,
files, documents, correspondence, memoranda, credit files and other data
relating to any Customer or Purchased Account, business papers, computers,
computer software (whether owned by Client or in which it has an interest),
computer programs, together with the tapes, disks, diskettes and other data and
software storage media and devices, File cabinets or containers in or on which
the foregoing are stored (including, without limitation, any of Client's rights
with respect to the foregoing maintained with or by any other person).

          "Requested Account" shall have the meaning set forth in Section 4(c).

          "Settlement Date" shall mean, with respect to any Purchased Account,
the date that is 90 days after the original due date of the Purchased Account.

          "Silicon" shall mean Silicon Valley Bank.

          "Term" shall have the meaning set forth in Section 11.

                                       11

<PAGE>

          "Trading Account Invoke" shall mean, with respect to any Purchased
Account, the Trading Account Invoice (as defined in the Trading Terms) with
respect thereto.

          "Trading Terms" shall mean the Arbinet-Thexchange United States
Exchange Delivery Point Member Trading Terms attached to a Customer Agreement.

          "UCC" shall mean the Uniform Commercial Code as in effect on the
Effective Date in the State of New York, as from time to time amended.

          '"Unpaid Fee" shall have the meaning set forth in Section 6(c).

     15.  CONFIDENTIALITY

     Except as may be required by applicable law, each party hereto agrees not
to disclose the terms of this Agreement or any of the transactions contemplated
hereby to any other person without the other party's prior written consent.

     16.  GENERAL

          (a) This Agreement may not be amended except in a writing signed by
each party hereto and is for the benefit of and binding upon the parties and
their respective successors and assigns except that Client may not assign or
transfer any of Client's rights or obligations under this Agreement without
Factor's prior written consent, and no such assignment or transfer of any such
obligation shall relieve Client thereof unless Factor has consented to such
release in a writing specifically referring to the obligation from which Client
is to be released. This Agreement, and any concurrent or subsequent written
supplements thereto or amendments thereof signed by each of Factor and Client,
represent the entire understanding of the parties and supersede all inconsistent
agreements and communications, written or oral, between Client's and Factor's
officers, employees, agents and other representatives.

          (b) This Agreement shall not be effective unless signed by Client and
Factor.

          (c) Except for Payment Requests delivered by Client in accordance with
Article 5, written communications made pursuant to this Agreement may be made by
email.

          (d) If any obligation to be performed pursuant to the Agreement is
required hereunder to be performed on a day that is not a business day, such
obligation shall be deemed to be required to be performed on the next succeeding
day that is a business day.

                                       12

<PAGE>

     IN WITNESS WHEREOF, each of Factor and Client has executed this Agreement
as of the Effective Date.

                                        SCM TELCO FINANCE LLC

                                        By:  /s/ Authorized Representative
                                            ------------------------------------
                                           Title:

                                        Address: c/o Corporation Service Company
                                                 2711 Centerville Road, Suite
                                                 400 Wilmington, DE 19808

                                        ARBINET-THEXCHANGE, INC.

                                        By:  /s/ Peter P. Sach
                                           -------------------------------------
                                           Title: CAO & Treasurer

                                        Address: 120 Albany Street Suite 450,
                                                 Tower II New Brunswick, New
                                                 Jersey 08901

                                       13

<PAGE>

SCHEDULES TO
FACTORING AGREEMENT
between
SCM TELCO FINANCE LLC
and
ARBINET-THEXCHANGE, INC.

Schedule 7(c)   Client Organization Information

                Organization Type: Corporation

                Jurisdiction of Organization: Delaware

                Organization Identification Number: 268341

                Federal Employer Identification Number: 13-3930916

Schedule 7(d)   Chief Executive Office:

                120 Albany Street, New Brunswick, New Jersey 08901

                Other Locations:

                1. 460 Herndon Pkway., Suite 150
                   Herndon, VA20170

                2. 441 Old Newport Blvd., Suite 104
                   Newport Beach, CA 92663

                3. 12/18 Paul Street
                   London EC2A 4JH

                                       14

<PAGE>

                                                                       Exhibit A

                                  TRADING TERMS

                                 (see attached)

                                       15

<PAGE>

                               ARBINET-TH EXCHANGE
                  UNITED STATES EXCHANGE DELIVERY POINT MEMBER
                                  TRADING TERMS

                                                               [LOGO] thexchange
                                                            Optimize Your World"

                                                                      Addendum B

1.   Introduction.

     (a) Arbinet-thexchange, Inc. ({"thexchange") provides an exchange for
facilitating the sale and purchase of telecommunication services by and between
telecommunications carriers, Internet telephony service providers, prepaid card
service providers and others. It is understood and agreed by Member that
thexchange's operation of the exchange does not constitute the provision by
thexchange of common carrier telecommunications services. Member agrees that it
will conduct all of its activities on the exchange in compliance with ail
applicable legal and regulatory requirements.

     (b) Thexchange may amend these Trading Terms or the Fee Schedule (Addendum
A) at any time by posting the amended Trading Terms or the Fee Schedule at
www.thexchanqe.com. The amended Trading Terms or Fee Schedule shall
automatically be effective thirty {30} days after they are initially posted on
www.thexchange.corn. Member agrees that such posting shall constitute reasonable
notice of such amendments. Thexchange shall notify Member's Primary Contact (as
specified in the Member Application) by fax or e-mail 30 days prior to the
effective date of any Trading Terms amendment. Member agrees that such web
posting and fax or e-mail notification shall constitute reasonable notice of
such amendments. Any changes to the contact information of the Primary Contact
must be communicated in writing to Member Services via e- mail to
Member.ServicesfSthexchanqe.com and such changes shall be effective upon receipt
by Member Services.

2.   Definitions.

The following terms as used herein have the meanings given to such terms in this
Section Z.

Answer Seizure Ratio (ASR) - The ratio of the number of seizures that result in
an answer signal, to the total number of seizures on a route or destination code
base during a specified time interval (as denned by the International
Telecommunications Union, ITU-T Terms and Definitions of Traffic Engineering
3/93).

Buy Order - A bid or buy offer by a Member to purchase minutes at a specific
price and quality.

Call Detail Record fCDR) - Call accounting record specifying the necessary call
information, such as date, duration, number called, etc.

Calling Code Inclusions and Exclusions - Country codes, city codes, prefixes or
exchanges designated to specific types or geographical areas or destinations
that are included or excluded from destination dialing (hereinafter referred as
"CCIE"), offered by Arbinet-thexchange and posted on the www.thexch3nge.com
website.

End Date - The termination date requested by a Member for a given Buy or Sell
Order.

Exchange Delivery Point - Any interconnect facility owned or operated by
thexchange, which provides Member with the ability to route (e.g., send or
receive) telecommunications traffic through the facility.

Member - An organization, which has received all membership approvals required
by thexchange and has been assigned a Member ID.

Route Plan Generation - An automated process of generating route plans based on
matched Buy and Sell Orders.

Sell Order - An ask or a sell offer by a Member to sell minutes at a specific
price and quality.

Start Dote - The commencement date requested by a Member for a given Buy or Sell
Order.

UTC - Coordinated Universal Time, formerly known as Greenwich Mean Time.

3.   Eligibility for Membership.

Member represents and warrants that it possesses all requisite legal and
regulatory authority to buy and/or sell, and transmit all telecommunications
services offered, sold or traded on thexchange.

4.   Thexchange is Only an Exchange.

Member acknowledges and agrees that (i) thexchange is an exchange for sellers
and for buyers to sell and buy telecommunications service for their own use;
(ii) thexchange is not responsible for and has no control over the quality,
safety or legality of telecommunications services offered or requested by
Members over the exchange, the truth or accuracy of any information provided by
Members, the ability of Members to sell telecommunications services or the
ability of Members to buy telecommunications services; and (iii) completion of
the sale of telecommunications services offered and purchased on the exchange is
solely the responsibility of Members and thexchange has no control of or
responsibility for Members' completion of the sale, purchase or delivery of
telecommunications services Members have agreed to trade.

5.   No Advice.

Member acknowledges that thexchange will not provide Member with any legal,
regulatory, tax or accounting advice, or advice regarding the appropriateness,
suitability or profitability of any transaction which Member undertakes on or
through thexchange. Member also acknowledges that thexchange's employees are not
authorized to give any such advice and that Member will not solicit or rely upon
any such advice from thexchange or any of its employees. Thexchange and its
officers, directors, employees, agents and affiliates will have no liability
with respect to any such advice.

6.   Credit Management.

     (a)  Thexchange reserves the right to impose such

Corporate Offices
120 Albany Street
lower II, t?' floor
New Brunswick, NJ 08901 USA
+1 732 509 9100
+1 732 509 9101 Fax

New York EDP
75 Broad Street
20* Floor
New York, NY 10004 USA
+1 917 320 2000
+1 917 320 1895 Fax

Los Angeles EDP
611 West' Street
12e' Floor
Los Angeles, CA 90017 USA
+1 80O"ARB]NET
+1 949 631 1237 Fax

London EDP 12/18 Paul
Street London EC2A 43H
United Kingdom +44 (0)
207 377 9449 +44 (0) 207
375 1854 Fax

Frankfurt vEDP
Itenos, Kleyerstrasse 90
60326 Frankfurt Am Main
Germany
+44 {0) 207 377 9449
+44 (0) 207 375 1854 Fax

<PAGE>

                                                                         arbinet
                                                               [LOGO] thexchange
                                                            Optimize Your World"

credit risk reduction management conditions on Member as are detailed in
thexchange's Credit Management Policy (attached hereto as Addendum C and as
amended from time to time), including, but not limited to, requiring authorized
trading deposits, advance payments and letters of credit, as thexchange deems
necessary and appropriate. Member agrees to the provisions of the Credit
Management Policy.

     (b) Changes to the Credit Management Policy will be reflected in the posted
policy thirty (30) days before such changes take effect. Member agrees tat
notification of Credit Management Policy changes by posting a revised.policy at
www.thexchange.com with contemporaneous notification by fax or e-mail to the
Primary Contact of Member, will constitute reasonable notice of such changes and
agrees to comply with such policy as amended from time to time.

7.   Member Responsibilities.

7.1  General

     (a) Member shall perform its obligations under these Trading Terms and use
the exchange in a manner consistent with applicable law, and shall not use the
exchange, or permit the exchange to be used, for any illegal purpose or in any
unlawful manner. Any Member's transmission of any and all material in violation
of any federal, state or local law, order or regulation is prohibited, and shall
constitute grounds for termination hereof by thexchange in its sole discretion.

     (b) Member is responsible for (i) provision of, and expenses associated
with, installation of all interconnection facilities and other actions necessary
for it to use thexchange and (ii) payment for all costs relating to equipment
and/or facilities obtained by thexchange on Member's behaLf.

     (c) Thexchange and Member will use reasonable best efforts to maintain the
security and confidentiality of any transactions conducted or information
transmitted through the exchange, subject to applicable law. Member acknowledges
that it is responsible for the security and confidentiality of information it
transmits through thexchange.

     (d) Member shall be responsible for (i) all trading and related activity on
the exchange and the www.thexchange.com website by all users of any of the
Member's trading accounts with thexchange and (ii) communicating the Trading
Terms set forth herein to such users. Alt such users will be deemed to have
read, understood and agreed to these Trading Terms. Member will provide to
thexchange in writing the names, addresses, telephone and fax numbers and email
addresses of all individuals, other than those listed in Member's member
application, authorized to trade on Member's behalf on the exchange. Such
notification shall be issued under Member's company letterhead and signed by
Member's Primary Contact or authorized representative.

7.2  Quality Standards for Selling Members

     (a) Member shall use its reasonable best efforts to verify that all
services provided by it through the exchange meet or exceed all quantitative and
qualitative service standards and route characteristics posted by or on behalf
of such Member on the exchange.

     (b)  [Intentionally left blank.]

     (c) Thexchange will from time to time (a) monitor the quality of the route
characteristics of the Member's network and (b) regrade and repost new quality
measurements on thexchange website and for Route Plan Generation. Member agrees
that the quality measurements of thexchange, not those of Member, shall govern
any dispute between Member and thexchange.

8.   Member Acknowledgments.

Member hereby acknowledges and agrees as follows:

     (a) Member is responsible for the accuracy of all orders and prices posted
by or on behalf of Member on the exchange. Thexchange assumes no responsibility
for any delays or errors in trade execution, for interruptions in
telecommunications services, or for misrouting of any telecommunications
services bought or sold by any Member through thexchange. Member agrees that
thexchange's CDRs and other records, not those of Member's, shall govern and be
used as the basis for any discussion or dispute or the resolution of any such
dispute. Member agrees to hold thexchange harmless from liability for any errors
or delays in trade execution or misrouting or interruptions in
telecommunications services, including but not limited to errors as to prices or
quality quoted by other Members. NOTWITHSTANDING ANY PROVISION TO THE CONTRARY
HEREIN, NEITHER THEXCHANGE NOR ITS AFFILIATES NOR MEMBER SHALL BE LIABLE FOR ANY
INDIRECT, SPECIAL, PUNITIVE OR CONSEQUENTIAL DAMAGES.

     (b) Sell prices posted on the exchange represent the seller's rates for
terminating minutes at the Exchange Delivery Points and are based on Member
orders. Member understands that other Members may make available limited
capacity at specified prices, and that a price displayed on thexchange may not
be available for all calls of similar characteristics at all times, as a result
of limited capacity.

     (c) [Intentionally left blank.]

     (d) [Intentionally left blank.]

     (e) Thexchange may, in its reasonable discretion, suspend, discontinue or
temporarily block Member's right to buy or sell telecommunications services
through thexchange, and remove or refuse to list any Order of the Member to buy
or sell telecommunications services if it deems such action necessary, either to
protect against improper use or to protect against fraud (e.g.. False Answer
Supervision or any other signal from Member, which tends to confuse, deceive,
disrupt or otherwise interferes with the network operation of other Members or
thexchange) or the commission of suspected illegal activities, or to otherwise
protect its personnel, agents, facilities or services, and/or arrange for
disconnection of Member's facilities interconnected with any Exchange Delivery
Point, without prior notice. Thexchange may terminate Member's membership for
any or no reasons and shall use reasonable efforts to provide Member whose
facilities are to be disconnected with advance notice of disconnection. Member
may, in its reasonable discretion, discontinue, suspend or temporarily block
services if it deems such action necessary, either to prevent improper use or to
protect against fraud or the commission of suspected illegal

Corporate Offices
120 Albany Street
Tower II, 4* Floor
New Brunswick, N3 OS901 USA
+1 732 503 9100
+1 732 509 9101 Fax

Hew York EDP
75 Broad Street
20* Floor
New York, NY 10004 USA
+1 917 320 2000
+1 917 320 1895 Fax

Los Angeles EDP
611 West ^ Street
12* Floor
Los Angeles, CA 90017 USA
+1 800 ARB1NFJ
+1 949 6311237 Fax

London EDP 12/18 Paul
Street London EC2A 43H
United Kingdom +44 (0)
207 377 9449 +44 (0) 207
375 1854 Fax

Frankfurt vEDP
Itenos, Kleyerstrasse 90
60326 Frankfurt Am Main
Germany
+44 (0) 207 377 9449
+44 (0) 207 375 1854 Fax

<PAGE>

                                                                         arbinet
                                                            ,. [LOGO] thexchange
                                                            Optimize Your World*

activities, or to otherwise protect its personnel, agents, facilities or
services. Member may discontinue participation on the exchange and may
discontinue membership on thexchange upon ten (10) days prior written notice to
thexchange. Member is responsible for any and all installation charges incurred
prior to the effective disconnection or discontinuation date. In the event
thexchange provides local access service to Member, Member must notify
thexchange in writing thirty (30) days in advance of such disconnection or
discontinuation. AH expenses incurred as a result of such disconnection or
discontinuation shall be the responsibility of Member.

     (f) If Member attempts to route traffic to a particular destination through
the exchange without providing a corresponding Buy Order, thexchange will use
commercially reasonable efforts to effect termination of such traffic, and
Member agrees to pay for such termination at the price obtained by thexchange,
plus any applicable fees.

     (g) If Seller receives and terminates a call for which it has no active
Sell order, the settlement rate of that call will be at the Seller's standard
published wholesale rate.

     (h) Thexchange shall be entitled to delete from the www.thexchanqe.coin
website any Buy Order or Sell Order posted by or on behalf of a Member if such
order has not been matched with a corresponding Sell Order or Buy Order or was
matched but Generated only negligible call volumes in the 30 days prior to such
deletion.

     (i) Thexchange will use commercially reasonable efforts to maintain the
accuracy of the Calling Code Inclusions and Exclusions ("CCIE") offered by
Arbinet-thexchange and posted on the www.thEXchanqe.com website. Thexchange will
use commercially reasonable efforts to update CCIE, but shall have no liability
for any of the information set forth in the CCIE and no obligation to update the
CCIE except upon receipt of written notice from the appropriate regulatory
authorities of changes in the information set forth on such list. All orders and
traffic routing on the exchange will occur based on the CCIE in effect at the
time of the relevant transaction. Thexchange shall not be responsible for
changes in prices that occur due to changes in codes, whether or not such codes
are reflected in the CCIE.

     0) Thexchange hereby grants to Member a non- exclusive, non-transferable,
personal right to access and use the information contained in the CCIE according
to the terms and conditions herein.

     (k) Member agrees the CCIE contains proprietary information of thexchange,
which is protected by copyright and other intellectual property laws. Thexchange
retains all rights in the CCIE and in any manner of distribution, including,
without limitation, all copyright and other proprietary rights worldwide. Member
shall not contest or otherwise interfere with such rights. Except as expressly
permitted under these Trading Terms and under U.S. copyright laws, Member may
not, or may not permit others to, reproduce, publish, distribute, sell, rent,
sublicense, lease, transfer, assign, access or provide access, use any
information retrieved from or contained ti the CCIE in any manner whatsoever or
alter, translate, modify, or adapt it to create derivative works of the CCIE.

     (l) Member acknowledges that Buy Orders and Sell Orders placed with a given
Start Date may become active as soon as the first scheduled Route Plan
Generation on or after said given Start Date is completed.

     (m) Member acknowledges that Buy Orders and Sell Orders placed with a
designated End Date will be deactivated as soon as the completion of the first
Route Plan Generation after the specified End Date that a Buy Order or Sell
Order has been requested to end.

     (n) Upon the request of thexchange, Member agrees to send, at Member's
cost, a summary of CDRs of traffic traded on the exchange to thexchange.

     (o) Member acknowledges that thexchange may from time to time combine or
break out destinations so as to simplify trading on the exchange; provided,
however, thexchange provides Member with 48 hours prior notice via e-mail.

9.   Payment/Settlement.

     (a) Subject to Section 9{d) below, thexchange will remit payment to Member
for traffic sold by Member through thexchange, and Member agrees to remit
payment to thexchange for traffic purchased by Member through thexchange, in
accordance with invoices issued by thexchange. Member also agrees to pay the
applicable fees as specified in the effective Fee Schedule. All fees will be
detailed by thexchange to Members. Thexchange reserves the right to modify,
impose new, or remove fees from the Fee Schedule pursuant to Section l(b) above.
Member is responsible for all applicable taxes and all other costs incurred by
Member in connection with participation on thexchange.

     (b) All traffic routed to a Seller at any U.S. Exchange Delivery Point will
be rated based on call durations measured by a thirty (30) second minimum period
followed by six (6) second billing increments. All traffic routed to a Seller at
the London Exchange Delivery Point will be rated based on call durations
measured by one (1) second billing increments. Notwithstanding the above, all
traffic routed to a Seller selling a destination in Mexico, regardless of the
particular Exchange Delivery Point the Seller is connected to, will be rated
based on a one (1) minute minimum period followed by one (1) minute billing
increments. Thexchange, in its discretion, may, from time to time on thirty (30)
days written notice by web posting and fax or e-mail, introduce additional call
duration measurement intervals pursuant to Section l{b) above.

     (c) All calculations and ratings of calls will be performed to the one
thousandth of a cent (US$x.xxxxx). Final settlements will be rounded up in the
Trading Account Invoice (as defined below) to the nearest whole cent (US$x.xx)
for each destination.

     (d) (i) Trading Account Invoice. Arbinet-thexchange shall issue invoices
relating to traffic (usage) traded on Arbinet-thexchange ("Trading Account
Invoice") twice monthly. The invoice dates shall be the first and the sixteenth
of a month (the "Invoice Date"). Trading Account Invoices bearing Invoice Dates
of the l" and 16th of a month shall detail Member's trading activities from the
16th through the last day of the previous month, and from

Corporate Offices
120 Albany Street
Tower II, 4* Floor
New Brunswick, N3 08901 USA
+1 732 509 91D0
+1 732 509 9101 Fax

New York EDF
75 Broad Street
20th Floor
Mew York, NY 10004 USA
+1 917 320 2000
+1 917 320 1S95 Fax

Los Angeles EDP
611 West 6* Street
12th Floor
Los Angeles, CA 90017 USA
+1 800 ARBINET
+1 949 631 1237 Fax

London EDP 12/18 Paul
Street London EC2A 40H
United Kingdom +44 (0)
207 377 9449 +44 (0) 207
375 1854 Fax

Frankfurt vEOP
Itenos, KleyerstrasseSO
60326 Frankfurt Am Main
Germany
+44 (0)(pound)07 377 9449
+44 (0) 207 375 1854 Fax

<PAGE>

                                                                         arbinet
                                                               [LOGO] thexchange
                                                            Optimize Your World*

the lst through the 15tfl of the month, respectively. The applicable due dates
for the Trading Account Invoices ("Trading Account Due Dates") are: for invoices
dated the f\ Trading Account payment ("Trading Account Payment") must be
received on or before the 15lfl of the same month; for invoices dated the 16vil,
Trading Account Payment must be received on or before the 30th of the same
month, except February, where payment must be received by March 2nd. If the
applicable Trading Account Due Date falls on a U.S. banking holiday or weekend,
then payment must be received no later than the business day immediately prior
to such banking holiday or weekend. As Member may be a net buyer or net seller
during a billing period ("Billing Period"), the Trading Account Due Dates shall
apply to Member or thexchange as the case may be. The Trading Account Invoice
and any accompanying trading account statements shall supersede any
contradictory or inconsistent reports issued by thexchange.

          (ii) Trading Account Payment Procedure. Member shall include
remittance advice detail ("Remittance Advice Detail") in the wire information
sent to thexchange. The Remittance Advice, Detail shall include: Member Name,
Member's Arbinet-thexchange Account Number, Invoice Number(s) and Invoice
Date(s) associated with the Trading Account Payment, and, if the Trading Account
Payment is different from the Invoice Amount, an explanation of discrepancies
between the Trading Account Payment and the Invoice Amount. If the Remittance
Advice Detail is not received by thexchange or its authorized agent, thexchange
or its authorized agent reserves the right to apply the Trading Account Payment
in the following order: {1} Trading Account Invoices (from the oldest to the
most current outstanding Trading Account Invoices), and (2) any outstanding
finance charges and collection fees. If there are funds remaining after applying
the Trading Account Payment to all outstanding Trading Account Invoices,
thexchange shall then apply the remaining funds to outstanding Member Account
Invoice(s) (as defined below) by applying the remaining funds from the oldest to
the most current outstanding Member Account Invoice. If excess funds remain
after applying the Trading Account Payment to alt Member Account Invoices,
thexchange will then retain the excess funds as prepayment for Member's current
or future trading activity unless Member requests in writing that the excess
funds be returned. Thexchange reserves the right to apply the excess funds to
Member's current trading activity on thexchange. The Remittance Advice Detail
shall supersede any inconsistent or contradictory instructions from Member
regarding the application of funds.

          (iii) Member Account Invoice. Arbinet- thexchange shall issue an
invoice relating to access to the exchange and services of Arbinet-thexchange
("Member Account Invoice"). The Member Account Invoice shall be dated the 2nd of
a month. Payments to thexchange for the Member Account Invoice shall be received
by thexchange no Later than the 261*1 of the month ("Member Account Due Date").
If the Member Account Due Date falls on a U.S. banking holiday or weekend, then
the Member Account payment must be received no later than the business day
immediately prior to such banking holiday or weekend. The Member Account Invoice
and any accompanying summary statements shall supersede any contradictory or
inconsistent reports issued by thexchange.

          (iv) Member Account Payment Procedure. Member shall include Remittance
Advice Detail (as defined above) in the wire information sent to thexchange. If
Member does not send Remittance Advice Detail as specified above, thexchange or
its authorized agent reserves the right to apply the Member Account Payment in
the following order: (1) outstanding finance charges and collection fees (if
any), and (2) Member Account Invoices (from the oldest to the most current
outstanding Member Account Invoices). If there are funds remaining after
applying the Member Account Payment to all outstanding Member Account Invoices,
thexchange shall then apply the remaining funds to outstanding Trading Account
Invoices by applying the remaining funds to the oldest to the most current
outstanding Trading Account Invoice. If excess funds remain after applying the
Member Account Payment to all Member Account Invoices, thexchange will then
retain the excess funds as prepayment for Member's current or future trading
activity unless Member requests in writing that the excess funds be returned.
Thexchange reserves the right to apply the excess funds to Member's current
trading activity on thexchange. The Remittance Advice Detail shall supersede any
inconsistent or contradictory instructions from Member regarding the application
of funds.

          (v) Member acknowledges and agrees that any amounts (including but not
limited to interest) payable to thexchange by Member for access, usage or other
fees may be deducted from my amount payable to Member by thexchange; such
offsetting may be done with respect to any invoice and/or among one or more
invoices. All amounts payable to thexchange by Member that remain unpaid on the
day after the applicable Due Date will bear interest from the Invoice Date at a
rate equal to the lesser of 18% per annum or the maximum amount permitted by
law.

          (vi) Thexchange will not accept funds from third parties or remit
payments to third parties, unless Member and thexchange agree otherwise in
writing.

          (vii) Member shall send payments to thexchange or its assignee by
electronic funds transfer as specified in thexchange's invoices. Thexchange wilt
charge the Member an administrative fee of 5250 if Member sends payments by
means other than electronic funds transfer. Thexchange reserves the right to
withhold payment if the total amount due Member is under $100. All costs
associated with electronic funds transfer shall be the responsibility of the
paying party.

     (e) If Member disputes any invoice or portions thereof, Member must provide
thexchange with written notice of the dispute (including the details thereof)
and accompanying documentation to support each claim within thirty (30) days of
the applicable invoice date; such notification should be delivered to
Arbinet-thexchange Member Services, at 460 Herndon Parkway, Suite 150, Herndon,
VA 20170 or e-mailed to billing@thexchange.com. The support documentation shall
include a written statement of the disputed amount, reasons for disputing such
amount, the order numbers (generated on thexchange trading floor) and CDRs in
Comma Delimited format (a csv file). The minimum required fields with the CDRs
are: Start Date, Start Time (UTC), Destination Number (dialed digits),
Destination Name, Duration, and Rate. Notification of such disputes does not
relieve Member from its obligation to remit the undisputed portion of invoices
on or prior to the applicable Payment Date. The parties shall work in good faith
to investigate and resolve all such settlement disputes. Accordingly, thexchange
wilt

Corporate Offices
120 Albany Street
Tower II, 4* Floor
New Brunswick, N3 08901 USA
+1 732 509 9100
+1 732 509 9101 Fax

New York EDP
75 Broad Street
20* Floor
New York, MY 10004 USA
+1 917 320 2000
+1 917 320 1895 Fax

Los Angeles EDP
611 West 681 Street
12* Floor
Los Angeles, CA 90017 USA
+ 1 800 ARBINET
+ 1 949 631 1237 Fax

London EDP 12/18 Paul
Street London EC2A 40K
United Kingdom +44 (0)
207 377 9449 +44 (0) 207
375 1854 Fax

Frankfurt vEDP
Itenos, Kieyerstrasse 90
60326 Frankfurt Am Main
Germany
+44 (0) 207 377 9449
+44 (0) 207 375 1854 Fax

<PAGE>

                                                               [LOGO] thexchange
                                                            Optimize Your World"

provide to Member a determination {the "Determination") no Later than ten (10)
business days from receipt of such notification and support documentation.
Member shall have no more than ten {10) business days from receipt of the
Determination to request in writing reconsideration thereof. Such request for
reconsideration shall inriude a detailed analysis and comparison of thexchange's
data with those of Member; otherwise, the reconsideration request will not be
accepted, Tiexchange reserves the right to review and resettle, if necessary,
invoices at any time for a period of thirty (30) days after the original invoice
has been issued as a result of thexchange's review of settlement data.
Thexchange settlement data shall be considered final unless demonstrated
otherwise.

     (f) Unless otherwise stated in the Fee Schedule, all fees are quoted in
U.S. Dollars. Member is responsible for paying all applicable taxes and for
other costs Member incurred to bid, buy, sell or access thexchange's facilities
or thexchange. Unless otherwise stated in the Fee Schedule, all settlement
payments between Member and thexchange shall be made in U.S. Dollars by
electronic funds transfer.

     (g) Member may maintain an open account vith thexchange to facilitate the
settlement of invoices.

     (h) In the event of non-payment by a Member, thexchange may in its sole
discretion direct traffic for termination to that Member in order to mitigate
risk through the netting process. In such event the settlement trade rate for
such traffic will be the fair market rate as determined by thexchange. In
addition, thexchange, in its sole discretion, may suspend, block and/or
disconnect Member's access to the exchange.

     (i) Member's consent shall not be required for any assignment or transfer
by thexchange to any third party of thsxchange's right to receive any monies due
to thexchange.

10.  Miscellaneous

     (a) In the event disputes exist between thexchange and Member, the
then-effective Trading Terms and Credit Management Policy shall govern,
supersede and be employed as the sole basis for determining all resolutions of
such disputes.

     (b) Nothing in these Trading Terms is intended to create any agency,
partnership or joint venture arrangement between thexchange and Member, nor are
there to be any third-patty beneficiaries hereunder.

     (c) Notwithstanding any provision herein to the contrary, thexchange
provides the www.thexchanqe.com website and thexchange's services "AS IS" AND
"AS AVAILABLE" AND MAKES NO EXPRESS WARRANTIES AND DISCLAIMS ALL IMPLIED
WARRANTIES, INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY AND OF
FITNESS FOR A PARTICULAR PURPOSE, with regard to the quality, capacity,
availability, reliability or other characteristics of thexchange, the
www.thexchanqe.com website or any telecommunications service offered by any
Member on thexchange. Member makes no express or implied warranty or condition
to thexchange or any other Member, whether of merchantability, fitness for a
particular purpose or otherwise with respect to any telecommunications services.

     (d) Thexchange's and Member's obligations are subject to, and they shall
not be responsible for, any delays, failure to perform or operation of
thexchange where such delay or failure is the result of fire, flood, water, the
elements, labor disputes or shortages, utility curtailments, power failures,
explosions, civil disturbances, acts of war, acts of God, governmental actions,
including but not limited to changes in regulations, tariffs, or rates, which
make it impossible or impractical for thexchange or Member to provide the
telecommunications services offered on thexchange or to fulfill the obligations
contemplated hereby.

     (e) These Trading Terms shall be interpreted in accordance with the laws of
the State of New York without regard to conflicts of Laws principles. Member
hereby consents to the exclusive jurisdiction of the federal or state courts
located in fie City and County of New York, with respect to all Legal actions
regarding these Trading Terms, or thexchange. Any and all disputes arising
hereunder which cannot be resolved by the parties hereto within thirty (30) days
of commencement of negotiations shall be resolved pursuant to arbitration
conducted in New York, New York pursuant to the rules of the American
Arbitration Association.

     (f) All rights to thexchange's intellectual property, including but not
limited to copyrights, patents, software, trademarks and service marks, shall
remain the sole property of thexchange.

     (g) These Trading Terms are subject to all present and future valid orders
and regulations of any governmental or regulatory body having jurisdiction over
the subject matter hereof and to the laws of the United States of America, any
of its states, or any foreign governmental agency having jurisdiction over the
parties hereto. In the event these Trading Terms shall be found contrary to or
in conflict with any such order, rule, regulation a law, these Trading Terms
shall be deemed modified to the extent necessary to comply with any such order,
rule, regulation or law and shall be modified in such a way as is consistent
with the form, intent and purpose hereof.

     (h) These Trading Terms constitute the entire understanding between
thexchange and Member with respect to the subject matter hereof.

     (i) Thexchange will use reasonable best efforts to protect the identity of
Member with respect to its transactions on thexchange. Thexchange may identify
Member as a Member of thexchange without specifying that such Member is a buyer
or seller.

     (j) Member's rights under the Member Application and all addenda and
amendments hereto are personal to Member and may not be assigned, sub-licensed,
or otherwise transferred in any fashion, regardless of whether such an
arrangement is characterized as an assignment, a sub-license, or any other
agreement.

Corporate Offices
120 Albany Street
Tower II, 4* Floor
New Brunswick, N3 08901 USA
+1 732 509 9100
+1 732 509 9101 Fax

New York EDP
75 Broad Street
Ztf Floor
New York, MY 10004 USA
+1 917 320 2DO0
+1 917 320 1895 Fax

Los Angeles EDP
611 West 6th Street
12* Floor
Los Angeles, CA 90017 USA
+1 800 ARBINET
+1 949 631 1237 Fax

London EDP 12/18 Paul
Street London EC2A 4JH
United Kingdom +44 (0)
207 377 9449 +44 (0) 207
37B 1854 Fax

Frankfurt vEFJP
Itenos, Kleyerstrasse 90
60326 Frankfurt Am Main
Germany
+44 (0) 207 377 9449
+44 (0) 207 375 1854 Fax<PAGE>
                                                                   EXHIBIT 10.23

                                 [LOGO] TEKELEC

                           STANDARD PURCHASE AGREEMENT

                                     BETWEEN

                                     TEKELEC

                                       AND

                            ARBINET-THEXCHANGE, INC.

Tekelec Business Confidential                                       Page 1 of 20

<PAGE>

This Standard Purchase Agreement (hereinafter "Agreement") is made between
Tekelec, a California corporation having an office at 5200 Paramount Parkway,
Morrisville, NC 27560 (hereinafter "TEKELEC"), and Arbinet-thexchange, Inc. a
corporation, with its principal place of business at 120 Albany Street, Tower
II, 4th Floor, New Brunswick, NJ 08901 (hereinafter "Buyer").

1.   AGREEMENT TO TERMS. These terms and conditions, and the appendices attached
     hereto, shall govern all sales by TEKELEC to Buyer. Except as expressly
     provided herein, this Agreement supersedes all prior or contemporaneous
     agreements, oral or written, and any other understandings between TEKELEC
     and Buyer relating to the subject matter of this Agreement.

2.   DEFINITIONS. For purposes of this Agreement, the following terms shall have
     the meanings set forth:

     2.1  "Conformance Test Plan." The term "Conformance Test Plan" shall mean a
          formal, written, mutually agreed upon set of tests to be performed by
          TEKELEC and/or Buyer to verify that the Products materially conform to
          the applicable specifications as set forth in associated TEKELEC
          technical publications, which describe the functionality of said
          Products.
     2.2  "Equipment," The term "Equipment" shall mean those hardware components
          which are manufactured, assembled, and/or installed by TEKELEC in the
          Products, such as printed wiring assemblies, plug-in circuits packs,
          back planes, shelves, frames and cables.
     2.3  "Initial Products." The term "Initial Products" shall mean those
          Products that are included on Buyer's initial order for a complete
          system.
     2.4  "Products." The term "Products" shall mean those TEKELEC products
          listed in the Quotation.
     2.5  "Quotation." The term "Quotation" shall mean a formal, written
          proposal prepared by TEKELEC as an offer to provide Products and
          Services to Buyer.
     2.6  "Services." The term "Services" shall mean those services performed by
          TEKELEC (or its representatives) under this Agreement, such as
          engineering, installation, training, shipping, warranty support,
          technical services, or other services as required.
     2.7  "Software." The term "Software" shall, mean any computer programs in
          object form or firmware incorporated into or otherwise accompanying
          any Product, and any replacement software therefor,
     2.8  "Spare Parts." The term "Spare Parts" shall mean the standard repair
          and replacement parts for the Products made available by TEKELEC from
          time to time.

3.   TERM. This Agreement will be effective as of May 19, 2003 (the "Effective
     Date") and continue thereafter for a period of twenty-four (24) months
     following the Effective Date (the "Term"), unless earlier terminated as
     provided herein. This Agreement may be extended by mutual agreement by both
     parties. The terms of this Agreement will continue in effect for any Order
     hereto that is outstanding at the time of termination of this Agreement or
     expiration of the Term.

4.   ORDERS. Any written Purchase Order or Statement of Work ("Order") issued by
     Buyer for Equipment, Software or Services which reference this Agreement,
     shall be deemed to be placed under and incorporate the terms and conditions
     of this Agreement and any Quotations issued by TEKELEC. Whenever the
     provisions of an Order conflict with the provisions of the Agreement, the
     typewritten provisions of the Order which are not preprinted as part of a
     form shall control. Printed provisions on the reverse side of Buyer's
     Orders shall be deemed deleted. TEKELEC reserves the right to reject any
     Order that is not in compliance with this Agreement and/or a Quotation. In
     addition, some Orders will be based on Quotations that contain multiple
     systems/subsystems that are able to function independently from one
     another. Some of these systems/subsystems may be delivered prior to the
     other systems/subsystems within the Quotation. Should this be the case, the
     Buyer agrees that the use and payment for each system/subsystem shall not
     be contingent upon the use and payment of the other undelivered
     systems/subsystem. These system/subsystem will be identified in the
     Quotation.

5.   PRICES. The prices for TEKELEC Products and Services are set forth in the
     Quotation(s). Such prices do not include import/export fees, duties,
     customs, value-added taxes ("VAT"), national, state or local taxes

Tekelec Business Confidential                                       Page 2 of 20

<PAGE>

     applicable to this transaction (excluding only taxes based on TEKELEC's
     income), which taxes will be added by TEKELEC to the price where TEKELEC
     has the legal obligation to collect the same and will be invoiced to and
     paid by Buyer, unless Buyer provided TEKELEC with a proper tax exemption
     certificate. Neither TEKELEC nor Buyer is responsible for any tax liability
     accruing to the other party, arising from income derived from this
     transaction. All prices are subject to change without notice.

6.   INVOICING AND TERMS OF PAYMENT. Unless otherwise set forth in a Quotation,
     TEKELEC shall invoice Buyer for all Products and Services (except Custom
     Extended Warranty Service) upon initial shipment of Order. Custom Extended
     Warranty Service shall be invoiced in accordance with Appendix A. All
     payments shall be made in U.S. Dollars. Payment for the Initial Products
     shall be due as follows: ninety percent (90%) of the total invoice amount
     shall be due thirty (30) days from the date of receipt of goods from the
     carrier at Buyer's designated site, and the remaining ten percent (10%)
     shall be due ninety (90) days from the date of the invoice, on approved
     credit. The terms of payment for all subsequent Orders for Products and
     Services shall be one hundred percent (100%) net due and payable thirty
     (30) days from the date of receipt of goods from the carrier at Buyer's
     designated site to Buyer, on approved credit. In the event Buyer does not
     pay an invoice when due, such invoice shall bear interest at the lesser
     rate of one and half percent (1.5%) per month or the maximum rate permitted
     by applicable law.

7.   SHIPMENT, TITLE AND RISK OF LOSS. For shipments to destinations within the
     United States Equipment and Software shall be delivered FOB destination and
     shipped to the destination designated by Buyer in its Order or otherwise in
     writing to TEKELEC. For shipments to destinations OUTSIDE the United States
     Equipment and Software shall be delivered DDU (Incoterms 2000) and shipped
     to the destination designated by Buyer in its Order or otherwise in writing
     to TEKELEC. Title to the Equipment and any media on which the Software is
     placed and risk of loss of or damage to the Equipment and Software shall
     pass to Buyer upon delivery to the destination designated by Buyer in its
     Order or otherwise in writing to TEKELEC. TEKELEC shall arrange for
     transportation of the Equipment and Software to the destination designated
     by Buyer. TEKELEC shall in its discretion select the mode of shipment and
     the carrier unless specific shipping instructions have been given by Buyer
     to TEKELEC. TEKELEC shall obtain transit insurance (subject to a nominal
     deductible) for the benefit of Buyer covering the shipment of the Equipment
     and Software. All costs of transportation, handling and insurance for the
     shipment of the Equipment and Software from TEKELEC's point of shipment to
     the destination designated by Buyer shall be prepaid by TEKELEC. Buyer
     shall reimburse TEKELEC for all transportation, handling and insurance
     charges that are incurred by TEKELEC in connection with the shipment of
     such Equipment and Software and separately stated on an invoice rendered to
     Buyer.

8.   EXPORT CONTROL LAWS. Both parties shall comply with the then current export
     and import laws and regulations of the United States and such other
     governments as are applicable when distributing the Equipment or Software.
     Both parties hereby certify that they will not directly or indirectly
     export, reexport, or transship the Equipment or Software or related
     information, media, or products in violation of United States laws and
     regulations. In the event that an export license is required to ship the
     Equipment or Software out of the United States, TEKELEC agrees that it will
     provide assistance to Buyer in obtaining such license.

9.   FORCE MAJEURE. Neither party shall be responsible for delays or failures in
     performance of this Agreement resulting from (1) acts or occurrences beyond
     reasonable control of such party (including, without limitation thereto,
     fire, explosion, power failure, lightning, severe weather, acts of God,
     war, revolution, civil commotion, any law, order, regulation, ordinance, or
     requirement of any government or legal body or any representative of any
     such government or legal body); (2) labor unrest (including, without
     limitation thereto, strikes, slowdowns, picket-lines, and boycotts whether
     primary or secondary, and without regard to whether such labor unrest could
     have been settled by acceding to the demands of a labor organization The
     affected party shall immediately notify the other party as to the nature
     and the extent of the force majeure. In the event that any such event of
     force majeure shall continue for more than sixty (60) days, then the
     parties shall enter into good faith negotiations directed toward a mutually
     acceptable resolution of outstanding obligations.

10.  INDEMNITY. Subject to Buyer's fulfillment of all Its obligations under this
     Agreement, TEKELEC will defend any suit or proceeding brought against Buyer
     insofar as such suit or proceeding shall be based upon

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<PAGE>

     a claim that the unmodified Software owned by TEKELEC infringes any United
     States patent or copyright (a U.S. Proprietary Right). Buyer shall notify
     TEKELEC in writing of any such suit or proceeding promptly upon Buyer's
     first learning of such suit or proceeding, and shall provide TEKELEC at no
     cost with such assistance and cooperation as TEKELEC may reasonably request
     in the defense thereof. TEKELEC shall have sole control over any such suit
     or proceeding, including, without limitation, the right to settle on behalf
     of Buyer on any terms TEKELEC deems desirable in the sole exercise of its
     discretion. Subject to Buyer's fulfillment of its obligations under this
     Section 10, TEKELEC shall pay all damages and costs finally awarded against
     Buyer (or payable by Buyer pursuant to a settlement agreement) in
     connection with any such suit or proceeding, provided, however, that
     TEKELEC's obligations to pay such damages and costs on behalf of Buyer
     shall not exceed the amounts paid by Buyer hereunder for such Equipment or
     Software. TEKELEC shall not enter into any settlement agreement pursuant to
     this Section 10 in excess of such amount without the prior consent of
     Buyer, which approval will not be unreasonably withheld. In the event that
     the Equipment or such Software becomes, or in TEKELEC's opinion is likely
     to become, the subject of a claim of infringement of a U.S. Proprietary
     Right, Buyer shall, upon receipt of written instructions from TEKELEC,
     cease to use such Equipment or Software and TEKELEC may at its option (i)
     modify the infringing Equipment or Software so that the use thereof by
     Buyer ceases to be infringing; or (ii) procure for Buyer the right to
     continue using the Equipment or Software as permitted hereunder; or (iii)
     if, neither (i) nor (ii) is commercially reasonable, demand the return of
     all units of the Equipment or Software and upon receipt thereof, refund to
     Buyer the depreciated value of said units of such Equipment or Software,
     based on a five (5) year straight line depreciation, and this Agreement
     shall terminate with respect to such Equipment or Software. TEKELEC shall
     have no liability to Buyer whatsoever for any loss or damage resulting from
     a claim of infringement or wrongful use of a U.S. Proprietary Right based
     upon and arising from (i) TEKELEC's compliance with Buyer's designs,
     specifications or instructions, (ii) the use of the Equipment or Software
     in combination with any equipment, products, software or data not
     manufactured, designed or assembled by TEKELEC, or (iii) any unauthorized
     alteration or modification of any Equipment or Software.

     The parties both agree to indemnify and hold harmless each other against
     any suit, claim or proceeding brought against the other party for direct
     damages that result from death, bodily injury or damage to personal,
     tangible personal property, to the extent the damages are proven to be the
     result of the indemnifying party's actions or inactions.

11.  TERMS OF WARRANTY AND TECHNICAL SERVICES.

     A.   The Standard Warranty (as defined in Appendix A) shall be effective
          for twelve (12) months from the completion of the Conformance Test
          Plan or Buyer's placement of Equipment and Software into service,
          whichever occurs first. In no event shall the period between TEKELEC's
          shipment and warranty commencement exceed ninety (90) days unless
          delay is solely attributable to TEKELEC. If purchased or otherwise
          provided, the Custom Extended Warranty Service (as defined in Appendix
          A) takes effect on the date of expiration of the Standard Warranty and
          can be renewed on a multi-year basis. Both the Standard Warranty and
          the Custom Extended Warranty Service include unlimited telephone
          support with TEKELEC Technical Assistance Center (TAC) at no extra
          charge. TAC normal operating hours are 8 a.m. to 8 p.m. ET, Monday
          through Friday excluding TEKELEC holidays. Emergency service hours are
          8 p.m. to 8 a.m. ET Monday through Friday, weekends and holidays.

     B.   TEKELEC warrants that during the Standard Warranty period, and the
          Custom Extended Warranty Service period, if applicable, TEKELEC will
          repair or replace defective Equipment in accordance with TEKELEC's
          Hardware Warranty (Appendix B).

     C.   TEKELEC warrants that during the Standard Warranty period, and the
          Custom Extended Warranty Service period, if applicable, TEKELEC will
          support Software delivered on the Products in accordance with
          TEKELEC's Software Warranty (Appendix C).

     D.   In the event that TEKELEC is unable to support the TEKELEC
          manufactured Products purchased by Buyer under this Agreement, TEKELEC
          will provide on an "as is" basis to Buyer, exclusively for its
          internal use and at no charge, all Software codes, hardware drawings
          and schematics necessary to

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<PAGE>

          maintain and support such Products. In such an event, Buyer's
          obligation to continue the Custom Extended Warranty Service payment is
          terminated.

     E.   TEKELEC's TAC will make available, at Buyer's expense, additional
          on-site or remote assistance as set forth in Appendix F, that may be
          requested by Buyer beyond the support that is provided under the
          Standard Warranty period or the Custom Extended Warranty Service.

     F.   EXCEPT AS EXPRESSLY STATED IN THIS AGREEMENT, THERE ARE NO WARRANTIES,
          EXPRESS OR IMPLIED, BY OPERATION OF LAW OR OTHERWISE. TEKELEC
          DISCLAIMS THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
          PARTICULAR PURPOSE AS TO BOTH TEKELEC AND NON-TEKELEC MANUFACTURED
          PRODUCTS.

12.  PRODUCT COMPLIANCE. TEKELEC will demonstrate to Buyer, within thirty (30)
     days following the installation of the Initial Products purchased under
     this Agreement, that such Products shall comply in all material respects
     with the Conformance Test Plan.

13.  LIMITATION OF LIABILITY

     A.   TEKELEC WILL NOT BE LIABLE TO BUYER. OR ANY OTHER PARTY FOR PUNITIVE,
          SPECIAL, INCIDENTAL, CONSEQUENTIAL, INDIRECT OR OTHER SIMILAR DAMAGES,
          INCLUDING, BUT NOT LIMITED TO, DAMAGES OR COSTS INCURRED AS A RESULT
          OF LOSS OF TIME, LOSS OF DATA, LOSS OF PROFITS OR REVENUE, OR LOSS OF
          USE OF THE EQUIPMENT OR SOFTWARE. IN ADDITION, TEKELEC IS NOT
          RESPONSIBLE OR LIABLE FOR DAMAGES OR COSTS IN CONNECTION WITH
          OBTAINING SUBSTITUTE EQUIPMENT OR SOFTWARE, CLAIMS BY OTHERS,
          INCONVENIENCE OR SIMILAR COSTS.

     B.   IN NO EVENT WILL TEKELEC'S LIABILITY FOR ANY DAMAGES TO BUYER OR ANY
          OTHER PERSON EXCEED THE PRICE PAID FOR THE EQUIPMENT OR LICENSE TO USE
          THE SOFTWARE, REGARDLESS OF THE FORM OF ANY CLAIM.

14.  SOFTWARE LICENSE. See Appendix D.

15.  PRODUCT CHANGE POLICY. See Appendix E.

16.  REMOTE ASSISTANCE. As part of each initial base system purchase, TEKELEC
     will provide remote assistance for Buyer's first interoperability and
     protocol conformance tests. TEKELEC Technical Service Center will remotely
     assist Buyer in their execution of Level 2 and 3 protocol conformance
     scripts on Buyer provided diagnostic equipment.

     If, through no fault of TEKELEC, Buyer's site, facilities or third-party
     negotiations (if any) are incomplete or are unready for the commencement of
     the scheduled TEKELEC-assisted interoperability tests, TEKELEC reserves the
     right to reschedule its participation in such tests.

17.  TRAINING. TEKELEC will make available training and training materials
     ("Training") to Buyer to enable Buyer to properly and effectively use the
     Equipment and Software. Training can be provided for the courses shown and
     at the costs listed in The Quotation. The cost and expense of travel to the
     North Carolina facility, and boarding and lodging of Buyer's personnel are
     the responsibility of the Buyer. The expenses incurred by TEKELEC Training
     personnel at the Buyer's site are the responsibility of the Buyer. Travel
     expenses incurred by TEKELEC Training personnel traveling to and from the
     Buyer's site are the responsibility of the Buyer.

18.  TERMS OF ANCILLARY EQUIPMENT. Ancillary equipment, including modems,
     terminals, and printers, shall be supplied by Buyer. If requested by Buyer,
     TEKELEC may supply ancillary equipment, accompanied by specifications and
     recommendations, if any, at the prices shown in the Quotation. The
     ancillary equipment shall carry the original equipment manufacturer's
     warranty, if any.

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19.  TERMS OF INSTALLATION. The installation of the Products will be performed
     by TEKELEC unless otherwise agreed upon between TEKELEC and the Buyer. The
     prices for installation shall be as set forth in the Quotation.

20.  SOFTWARE. Notwithstanding the "purchase" and "sale" language and similar
     terms hereof, the Buyer understands that any Software furnished by TEKELEC
     whether on magnetic media, semiconductor chips or file transfer protocols,
     is not sold to Buyer, but is licensed to Buyer under the terms and
     conditions set forth in TEKELEC's Software License (Appendix D).

21.  CANCELLATION. Buyer may cancel this Agreement only with TEKELEC's prior
     written approval and the payment of reasonable charges pursuant to any
     outstanding Orders as determined by TEKELEC.

22.  CONFIDENTIALITY. For purposes of this Agreement, "Confidential Information"
     shall mean any information or material that is proprietary to the
     disclosing party or designated in writing as Confidential Information by
     the disclosing party and not generally known to the public. Confidential
     Information also includes information that the disclosing party obtains
     from any third party that the disclosing party treats as proprietary or
     designates as Confidential Information, whether or not owned by the
     disclosing party. "Confidential Information" does not include the
     following:

          i.   information which is known by the receiving party at the time of
               receipt from the disclosing party which is not subject to any
               other non-disclosure agreement between the parties;
          ii.  information which is now, or which hereafter becomes, generally
               known to the industry through no fault of the receiving party, or
               which is later published or generally disclosed to the public by
               the disclosing party; or
          iii. information which is otherwise lawfully developed by the
               receiving party, or lawfully acquired from a third party without
               any obligation of confidentiality.

     The receiving party agrees to hold in confidence and not to disclose or
     reveal to any person or entity any Confidential Information disclosed
     hereunder without the clear and express prior written consent of a duly
     authorized representative of the disclosing party. The receiving party
     further agrees not to use or disclose any of the Confidential Information
     for any purpose at any time, other than for the limited purpose(s)
     expressly authorized by this Agreement. In the event that either party is
     directed to disclose any portion of any Confidential Information of the
     other party or any other materials proprietary to the other party in
     conjunction with a judicial proceeding or arbitration, the party so
     directed shall immediately notify the other party both orally and in
     writing. Each party agrees to provide the other with reasonable cooperation
     and assistance in obtaining a suitable protective order and in taking any
     other steps to preserve confidentiality.

23.  NOTICES. All notices required under this Agreement shall be in writing and
     shall be given by personal delivery, telecopier, international courier
     service of recognized reputation (e.g., DHL), or by airmail, certified or
     registered, postage prepaid, return receipt requested, to the parties at
     their respective addresses set forth below. All notices shall be deemed
     effective upon personal delivery, or one (1) business day following receipt
     by telecopier, or seven (7) days following deposit in the mail, or three
     (3) business days following deposit with any international courier service
     of recognized reputation (e.g., DHL).

          TEKELEC
          Contact Name: Contracts Manager
          Address: 5200 Paramount Parkway
                   Morrisville, NC 27560
          Telephone No.: (919)461-5500
          FAX No.: (919)388-1416

          BUYER
          Contact Name: Peter P. Sach
          Address: 120 Albany Street. Tower II, 4th Floor
                   New Brunswick, NJ 08901
          Telephone No.: 732-509-9100
          FAX No.: 732-509-9101

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24.  GENERAL PROVISIONS. This Agreement shall be construed and enforced in
     accordance with the laws of the State of California which are applicable to
     the construction and enforcement of contracts between parties resident in
     California which are entered into and fully performed in California. If
     either party brings an action against the other party to enforce its rights
     under this Agreement, the prevailing party shall be entitled to recover its
     costs and expenses, including without limitation, attorney's fees and costs
     incurred in connection with such action, including any appeal of such
     action. With respect to all disputes arising out of or related to this
     Agreement or the transactions contemplated hereunder, the parties hereby
     submit to the personam jurisdiction of the state and Federal courts in Los
     Angeles, California.

     Buyer shall not assign this Agreement or any interest herein or right
     hereunder other than to a successor to its entire business and goodwill or
     that part of its business used in the performance of this Agreement without
     the prior written consent of TEKELEC. This Agreement shall be binding upon
     and inure to the benefit of the successors and assigns of each party as
     permitted herein.

     No waiver of any provision of this Agreement shall be effective unless made
     in writing. No waiver of any breach of any provision of this Agreement
     shall constitute a waiver of any subsequent breach of the same or of any
     other provision of this Agreement. In the event that any provision hereof
     is found invalid or unenforceable pursuant to judicial decree or decision,
     the remainder of this Agreement shall remain valid and enforceable
     according to its terms.

     Each party's obligations under this Agreement that by their nature would
     continue beyond expiration or termination of this Agreement, shall so
     survive such expiration or termination. This Agreement shall not be
     modified, amended or in any way altered, except by an instrument in writing
     signed by authorized representatives of TEKELEC and Buyer.

25.  ACCEPTED AND AGREED UPON:

TEKELEC                                  ARBINET THEXCHANGE, INC

By:    /s/ Lori A. Craven                By:   /s/ Peter P. Sach
    ----------------------------------       -----------------------------------

Print: LORI CRAVEN                       PRINT: Peter P. Sach

TITLE: VP & GM NSD                       TITLE: CAO & TREASURER

DATE: 5/20/03                            DATE: May 19, 2003

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                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                             Warranty Provisions
                                                                      Appendix A

                            TEKELEC STANDARD WARRANTY

The Standard Warranty is included, at no charge, for all Products purchased by
Buyer under this Agreement.

The Standard Warranty provides:

1.   Hardware repair and return,
2.   Software problem resolution,
3.   Unlimited telephone access to the Technical Assistance Center (24 hrs. per
     day, 7 days per week), and
4.   Any Feature Constant Generic Software Loads released and installed during
     the coverage period.

For Hardware and Software, the Standard Warranty expires twelve (12) months
after completion of the Conformance Test Plan or twelve (12) months after the
Hardware and Software are placed into service, whichever occurs first. In no
event shall the Standard Warranty commence later than ninety (90) days following
shipment, unless a delay is solely attributable to TEKELEC.

Hardware extensions and Software problem resolution is provided for additional
Product(s) purchased after the Initial Products, is warranted for ninety (90)
days or the balance of any remaining standard warranty coverage, whichever is
longer.

Under the Standard Warranty, TEKELEC will repair or return defective Equipment
with functionally equivalent Equipment during the coverage period. Repaired or
replaced Equipment is warranted for ninety (90) days or the balance of any
remaining warranty coverage, whichever is longer.

Provided that the Software delivered and maintained by TEKELEC has not been
altered by the Buyer, without authorization, TEKELEC warrants that (i) the
Software shall be readable and executable for the hardware for which it was
designated and (ii) the Software (including Feature Constant Generic Software
Loads) will, upon proper configuration, conform materially to the applicable
specifications as set forth in associated TEKELEC technical publications, which
describe the functionality and performance of said Software. Feature Constant
Generic Software Loads are limited to minor patches and bug fixes and do not
include upgrades or new software feature modules.

All ancillary equipment not manufactured by TEKELEC, to be supplied under this
Agreement, shall carry the original equipment manufacturer's warranty, if any.

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                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                             Warranty Provisions
                                                                      Appendix A

                        TEKELEC CUSTOM EXTENDED WARRANTY

To meet each Buyer's individual needs, TEKELEC offers a custom warranty service
called Custom Extended Warranty Service (CEWS), providing continued coverage
after the expiration of the Standard Warranty.

Buyer may elect to enroll in the optional Custom Extended Warranty Service plan
that provides additional multi-year continued coverage that includes:

..    a continuation of telephone access to the Technical Assistance Center and
     Software problem resolution, as per the Standard Warranty;
..    hardware repair and return;
..    Feature Constant Generic Software Loads released and installed during the
     coverage period. (Feature Constant Generic Software Loads are limited to
     minor patches and bug fixes and do not include upgrades or new software
     feature modules.); and
..    50% discount from the then-current list price for any Hardware or Software
     prerequisites required to purchase additional functionality for previously
     purchased equipment covered under CEWS.

CEWS coverage is purchased in multi-year terms, which will be billed on an
annual basis. Pricing for CEWS is 10% of the then-current list-price for the
system value.

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                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                             Warranty Provisions
                                                                      Appendix A

                       CUSTOM EXTENDED WARRANTY PROVISIONS

Invoicing for Custom Extended Warranty Service will occur in annual
installments. Invoices will be issued at least thirty (30) days prior to the
expiration of the current year's coverage. The basis of each annual installment
will be adjusted to reflect the then-current list value of the system and the
appropriate percentage will be calculated from the new basis, along with any
additional third party maintenance fees identified in The Quotation.

If Custom Extended Warranty Service coverage is desired, any time after initial
system purchase, TEKELEC reserves the right to audit said system for minimum
levels of maintainability and suitability for coverage under the Custom Extended
Warranty Service plan. Pricing for each tier will be adjusted to reflect the
general system condition.

Generic Vintage Requirements

Under both the Standard Warranty and Custom Extended Warranty Service, TEKELEC
will support the current generic release and two (2) previous releases.

WARRANTY LIMITATIONS:

AS PART OF TEKELEC'S CONTINUOUS IMPROVEMENT PROGRAM, GENERIC SOFTWARE LOADS MAY,
FROM TIME TO TIME, REQUIRE PREREQUISITE CHANGES TO BASE LEVELS OF HARDWARE.
COSTS ASSOCIATED WITH THESE "CLASS B" CHANGES ARE THE RESPONSIBILITY OF THE
BUYER AND ARE NOT COVERED UNDER EITHER THE STANDARD WARRANTY OR THE CUSTOM
EXTENDED WARRANTY SERVICE. TEKELEC MAY, IN ITS SOLE DISCRETION, ELECT TO OFFER
CERTAIN COMMERCIAL INCENTIVES TO THOSE USERS WISHING TO PARTICIPATE IN A
PARTICULAR "CLASS B" OFFERING. TEKELEC WILL USE ITS REASONABLE EFFORTS TO
MINIMIZE THE FREQUENCY, IMPACT AND COSTS OF ALL "CLASS B" OFFERINGS. REFER. TO
TEKELEC'S HARDWARE WARRANTY POLICY FOR ADDITIONAL DETAILS.

UPGRADES AND NEW SOFTWARE FEATURE MODULES ARE NOT COVERED BY THE STANDARD
WARRANTY OR BY THE CUSTOM EXTENDED WARRANTY SERVICE, AND MUST BE PURCHASED
SEPARATELY.

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                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                             Warranty Provisions
                                                                      Appendix A

NEITHER THE STANDARD WARRANTY NOR THE CUSTOM EXTENDED WARRANTY SERVICE COVERS
MATERIAL THAT HAS BEEN LOST, STOLEN, OR DAMAGED BY ACCIDENT, MISUSE, OR
UNAUTHORIZED MODIFICATION OR INSTALLATION; NOR DO THE WARRANTY SERVICES INCLUDE
INSTALLATION OR RELOCATION OF THE AFFECTED EQUIPMENT.

WHEN NOT COVERED BY EITHER THE STANDARD WARRANTY OR THE CUSTOM EXTENDED WARRANTY
SERVICE, REPAIR AND RETURN OF FAILED COMPONENTS WILL ENTAIL A HANDLING FEE, PER
FAILED COMPONENT AND HOURLY REPAIR AND MATERIAL CHARGES. WHERE POSSIBLE, TEKELEC
CUSTOMER SERVICE WILL PROVIDE THE BUYER WITH BUDGETARY ESTIMATES OF
COSTS-TO-REPAIR. A NEW COMPONENT WILL BE SUBSTITUTED FOR ANY FAILED COMPONENT,
WHEN REPAIR COSTS ARE ESTIMATED TO EXCEED LIST PRICE OF THE COMPONENT.

ALL ANCILLARY SUPPORT EQUIPMENT, SUCH AS VIDEO DISPLAY UNITS, KEYBOARDS,
PRINTERS, MODEMS, VOLTMETERS, OSCILLOSCOPES, SS7 TRAFFIC SIMULATION OR
SURVEILLANCE EQUIPMENT, SS7 OR LAN PROTOCOL ANALYZERS, DIGITAL TRANSMISSION TEST
EQUIPMENT, ETC., SHALL BE CONSIDERED ORIGINAL EQUIPMENT MANUFACTURER ("OEM")
EQUIPMENT, AND WILL CARRY ONLY THE OEM WARRANTY, IF ANY.

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                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                               Hardware Warranty
                                                                      Appendix B

                            TEKELEC HARDWARE WARRANTY

TEKELEC warrants that during the warranty period, the TEKELEC manufactured
hardware will be free of any material physical defects. During the warranty
period, TEKELEC will repair or replace defective Equipment with functionally
equivalent Equipment.

What is covered:

TEKELEC Equipment consists of printed wiring assemblies, plug-in circuit packs,
back planes, shelves, frames and cables manufactured, assembled and installed by
TEKELEC in the Products. On a normal basis, TEKELEC will provide repair or
functionally equivalent replacement of circuit packs within seven (7) calendar
days of TEKELEC's receipt of the defective Equipment, or in the case of
emergencies, within twenty-four (24) hours, if advance replacement is requested
by Buyer.

As a convenience to the Buyer, various ancillary support equipment, such as
video display units, keyboards, printers, modems, voltmeters, oscilloscopes, SS7
traffic simulation or surveillance equipment, SS7 or LAN protocol analyzers,
digital transmission test equipment, etc., may be purchased from TEKELEC and
supplied along with the Products under the terms of the Order. Such ancillary
support equipment shall be considered OEM equipment and will carry the OEM
warranty, if any.

Duration of Coverage:

TEKELEC Equipment is covered under warranty for twelve (12) months from the
completion of the Conformance Test Plan or Buyer's placement of the Equipment in
commercial service, whichever occurs first. In no event shall the period between
TEKELEC's shipment and warranty commencement exceed ninety (90) days unless
delay is solely attributable to TEKELEC. For Equipment additions, either working
or held as spare, TEKELEC Equipment is covered by the limited warranty for three
(3) months following shipment to Buyer or the balance of the Initial Product,
whichever is longer. Ancillary equipment shall be covered under the tennis and
conditions of the warranty supplied to TEKELEC by the original equipment
manufacturer, if any. The warranty for repaired or replaced Equipment is ninety
(90) days, or the balance of the original warranty, whichever is longer.

Buyer's Procedure for Obtaining Warranty Service:

1.   Contact TEKELEC's Technical Assistance Center ("TAC") to assist with
     confirmation of the defect and, if necessary, obtain a Return of Materials
     Authorization ("RMA") number. The TEKELEC TAC number is (919) 460-2150 or
     1-800-432-8919.
2.   Supply the following information to the TAC:
          -Buyer's Name, Address and Telephone Number,
          -Product Model and Serial Numbers,
          -Date and description of the problem experienced.
3.   Return defective Equipment to TEKELEC, as advised by the TAC, which will
     assist in identifying suspected faulty components and will recommend which
     (if any) must be returned.
4.   All returned Equipment must be shipped to the facility specified by the
     TAC, freight prepaid, in the original carton or equivalent, with shipping
     label clearly specifying the assigned RMA number. TEKELEC will use
     commercially reasonable efforts to repair or replace and return defective
     Equipment within seven (7) calendar days of receipt. TEKELEC will ship
     repaired or replaced Equipment freight prepaid. If Equipment returned is
     determined by TEKELEC not to be defective, TEKELEC may invoice for all
     related costs incurred including shipment.
5.   In the event Buyer has requested emergency advance replacement, and the
     defective Equipment is not received by TEKELEC within thirty (30) days
     following such replacement, TEKELEC shall invoice Buyer for the full list
     price of the advance replacement Equipment.

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<PAGE>

                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                               Hardware Warranty
                                                                      Appendix B

Class of Hardware Change:

Class A applies to changes required to correct a Product deficiency, such as, a
safety or fire hazard, electrically or mechanically inoperative Equipment,
operational or design defects that lead to higher than promised failure rates,
or a defect that causes the Product not to operate as documented in Product or
feature specifications, as warranted or specified in the purchase Agreement.

Class A Hardware Changes will be effected by replacement of affected Equipment
at TEKELEC's initiative, and the Buyer will not be billed for Class A Changes.

Class B applies to changes made to incorporate design improvements resulting in
better operation, improved testing or maintenance, longer life, service
improvement, cost reductions or feature additions.

Class B Hardware changes will be provided by TEKELEC only upon receipt of an
order from the Buyer, and the Buyer will be billed for Class B Changes.

Class D applies to changes that incorporate minor new features and design
improvements that do not affect existing functionality, such as those made to
facilitate manufacture or to effect a supplier cost reduction.

Class D Hardware Changes will be incorporated into newly manufactured Products
at TEKELEC's discretion, and will in no case cause unfavorable deviation from
standard prices or billing procedures for the Buyer.

Tekelec Business Confidential                                      Page 13 of 20

<PAGE>

                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                               Software Warranty
                                                                      Appendix C

                            TEKELEC SOFTWARE WARRANTY

TEKELEC warrants that during the warranty period, provided that the Software has
not been altered or modified by the Buyer, without TEKELEC's expresses written
permission:

1)   the Software delivered on the delivery medium will be readable and
     executable by the designated hardware (microprocessors) for which the
     Software is licensed; and

2)   upon proper configuration of the Software and designated hardware for which
     the Software is licensed, such Software will materially conform to the
     applicable user's guide and the associated TEKELEC documentation that
     describe functionality and performance of the Software.

What is covered:

"Software" in this warranty means the computer programs in object form and
system specific data loaded either on fixed or removable cartridge disks, or
recorded on semiconductor chips that are integral to TEKELEC plug-in equipment,
together with upgrades or modifications subsequently supplied by TEKELEC.
"Software copies" means actual copies of all or any portion of the Software,
including backups, upgrades, merged or partial copies that are permitted under
the terms of TEKELEC's Software License (Appendix D). "Related Documents" refers
to printed materials provided with Software or Software copies describing the
Software, its installation, or its use. During the warranty period, TEKELEC will
correct significant errors in the Software or Related Documents that render
either unusable, as defined in the Category of Software Changes section below,
with efforts TEKELEC believes suitable for the problem or, at TEKELEC's option,
furnish Software Maintenance Loads or Feature Constant Generic Software Loads.

Duration of Coverage:

TEKELEC Software is covered under warranty for twelve (12) months from the
completion of the Conformance Test Plan or Buyer's placement of the Software in
commercial service, whichever occurs first. In no event shall the period between
TEKELEC's shipment and warranty commencement exceed ninety (90) days unless
delay is solely attributable to TEKELEC. The warranty period for Software
Changes shall be ninety (90) days from the date the Software Change is effected,
or the remainder of the initial Software warranty, whichever is longer.

Buyer's Procedure for Obtaining Warranty Service:

To report or inquire about suspected Software and/or Related Document errors:

1)   Refer to the Category of Software Changes section below regarding the
     general guidelines for Software error identification, notification and
     resolution.
2)   Contact TEKELEC's Technical Assistance Center (TAC) to assist with
     confirmation of the defect and, if necessary, arrange to receive a Customer
     Service Request Number ("CSR"), for tracking purposes. The TEKELEC TAC
     number is (919) 460-2150 or 1-800-432-8919.
3)   Supply the following information to the TAC:
          a)   Buyer's Name, Address and Telephone Number,
          b)   Software Model and Serial Numbers;
          c)   Date and description of the problem experienced.

Tekelec Business Confidential                                      Page 14 of 20

<PAGE>

                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                               Software Warranty
                                                                      Appendix C

Any Software Changes or modifications become part of the Software licensed to
Buyer pursuant to the terms of TEKELEC standard Software License.

TEKELEC Customer Support Procedures:

TEKELEC, through its TAC staff, will provide, at its option, telephone support
or on-site assistance to Buyer in the use and operation of the most recent
release and the two (2) immediately preceding versions of the Software. The TAC
provides support twenty-four (24) hours a day, seven (7) days a week. This
includes emergency recovery support. TEKELEC TAC engineers have remote access
capabilities to every site, enabling them to work with Buyer's on-site
technicians.

Category of Software Changes:

1.   CRITICAL

Critical applies to Software Changes required to correct (fix) a Software
deficiency, such as, a fatal program error that forces continuous restarts,
inoperative Software that produces erroneous results (misrouted messages,
garbled or incorrect records, etc.) or a defect that causes the product not to
perform as documented in feature specifications, or as warranted/specified in
the purchase Agreement.

Critical Software Changes will be effected via Software maintenance loads or
Generic Software Loads (GSLs) at TEKELEC's initiative, and the Buyer will not be
billed for Critical Software Changes.

Critical Software Changes result from troubles characterized as Critical or
Major.

Critical troubles are those that severely affect service, traffic or maintenance
capabilities, and require immediate corrective action, regardless of the time of
day or the day of the week.

Critical troubles include, but are not limited to:

..    total system failures that result in the loss of all transaction processing
     capability (i.e., message routing and transmission);
..    significant reduction in system capacity or traffic handling capability;
..    loss of safety or emergency rerouting capability;
..    inability to restart a system processor;
..    loss of access for maintenance or recovery operations; and
..    loss of the system's ability to provide any required critical or major
     trouble notification.

The resolution time for Critical troubles is continuous around-the-clock support
until pre-incident condition exists.

Tekelec Business Confidential                                      Page 15 of 20

<PAGE>

                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                               Software Warranty
                                                                      Appendix C

2.   MAJOR

Major troubles are those that seriously affect system operation, maintenance and
administration, etc. and also require immediate action. However, the urgency is
less than for Critical troubles because of a less immediate or impending effect
on system performance, or a lesser impact on the operations and revenues of the
Buyer or its customers.

Major troubles will be effected via Software Maintenance Loads or Feature
Constant Generic Software Loads at TEKELEC's initiative and the Buyer will not
be billed for Major Software Changes.

Major troubles include:

..    reduction in any capacity or traffic measurement function;
..    any loss of functional viability or diagnostic capability.

The resolution time for Major troubles is thirty (30) days from Tekelec's
receipt of trouble notification from Buyer.

3.   MINOR

Minor applies to Software Changes made to incorporate design improvements
resulting in more efficient operation, improved testing or maintenance, or cost
reductions. Minor Software Changes result from troubles characterized as Minor.

Minor Software Changes will be provided, if commercially feasible, in the next
higher Feature Constant Generic Software Loads offered to Buyers covered by the
Standard Warranty or Tier 3 Custom Extended Warranty Service), or upon receipt
of an Order from Buyers who are not covered by the Standard Warranty or Tier 3
Custom Extended Warranty Service. The latter group will be billed for this
release either according to a published price list or a prior negotiated
purchase agreement, if applicable.

Minor troubles include

..    all non-service affecting troubles, nuisances or document errors.

Tekelec Business Confidential                                      Page 16 of 20

<PAGE>

                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                                Software License
                                                                      Appendix D

                            TEKELEC SOFTWARE LICENSE

EFFECTIVE DATE

This Software License shall become effective upon delivery of the Equipment and
Software.

DEFINITIONS

The term "Software" as used in this Agreement means the computer programs in
object form either in diskettes, transferred to the Equipment by various File
Transfer Protocols, or recorded on semiconductor chips that are part of the
TEKELEC Equipment, together with any upgrades, update or modifications
subsequently supplied by TEKELEC.

The term "Software Copies" means the actual copies of all or any portion of the
Software, including backups, upgrades, updates, merged or partial copies
permitted hereunder or subsequently supplied by TEKELEC.

The term "Related Materials" means all of the printed materials provided in this
package or later supplied by TEKELEC for use with the Software.

GRANT OF LICENSE

In consideration of the license fees stated in The Quotation, and of Buyer's
agreement to abide by the terms and conditions of this Agreement, TEKELEC hereby
grants to the Buyer a nonexclusive, nontransferable, perpetual, limited
Right-To-Use (RTU) license to use the Software identified in the Quotation on
the Equipment that is being supplied by TEKELEC to Buyer under this Agreement.
This RTU license is limited to use of the object code programs and related
documentation only and does not apply to any of the corresponding source code or
program listings.

PERMITTED USES

Buyer may:
     .    Load onto and use the Software on a single (1) TEKELEC system or those
          logical units that constitute a single (1) logical system.
     .    Install the Software onto a permanent storage device (a hard disk
          drive).
     .    Make and maintain back-up copies provided they are used only for
          back-up purposes, and Buyer maintains possession of the back-ups. In
          addition, all information appearing on the original disk labels
          (including the copyright notice) must be copied onto the back-up
          labels.

USES NOT PERMITTED

Buyer may not:
     .    Make copies of the Software, except as permitted above.
     .    Make copies of the Related Materials, except as permitted above.
     .    Rent, lease, sub-license, time-share, lend, or transfer the Software,
          Software Copies, Related Materials or Buyer's rights under this
          license except that transfers may be made with TEKELEC's prior written
          authorization.
     .    Alter, decompile, reverse engineer, or disassemble the Software, or
          make attempts to unlock or bypass initialization used on initialized
          disks, except as directed by TEKELEC's Technical Assistance Center
          staff.

Tekelec Business Confidential                                      Page 17 of 20

<PAGE>

                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                                Software License
                                                                      Appendix D

PROPRIETARY RIGHTS

Buyer acknowledges and agrees that TEKELEC retains all copyright, patent, trade
secret, trademark and trade name rights in the Software, Software Copies and all
Related Materials, and Buyer shall not acquire any right, title, or interest
therein, including any right, title or interest in any changes, modifications
and adaptations made by Buyer to the Software, the Software Copies and Related
Materials. Buyer agrees that it will not at any time during or after the term of
this Agreement assert or claim any interest in, or do anything which may
adversely affect the validity or enforceability of, any trademark, trade name,
copyright or logo belonging to or licensed to TEKELEC (including any act, or
assistance to any act, which may infringe or lead to the infringement of any
proprietary right in the Software, Software Copies or Related Materials). Buyer
will not remove or obscure any proprietary rights notice contained on or
incorporated in the Software, Software Copies or Related Materials.

TERMINATION.

In the event Buyer is in breach of any of their obligations under this Software
License, and such breach continues unremedied for a period of thirty (30) days
after written notice is given thereof, then in addition to all other rights and
remedies of law or equity, TEKELEC shall have the right to terminate this
Software License. In the event of such termination, Buyer shall immediately
cease its use of the Software, and shall return all Software, Software Copies,
and Related Materials to TEKELEC.

Tekelec Business Confidential                                      Page 18 of 20

<PAGE>

                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                           Product Change Policy
                                                                      Appendix E

                          TEKELEC PRODUCT CHANGE POLICY

Thirty (30) days in advance of the release of any revision to Equipment or
Software, a Product Change Notice (PCN) will be published and sent to all of
TEKELEC's customers. This group includes both current users with Products in
service and future users who have already signed a purchase order for one or
more Products. PCNs will be issued for all hardware changes, Classes A, B or D,
as well as Feature Constant Generic Software Loads. When a Generic Software Load
includes major new features, a PCN supplement will be included to describe their
operation and specific impact on systems in service.

TEKELEC Product Change Notices contain the following information.

1.   The PCN number, issue date and change classification that corresponds to
     this specific revision.

2.   Name, address and telephone number of the TEKELEC contact person to arrange
     hardware or Software upgrades.

3.   Complete description of affected product(s) and system(s).

4.   The unique product code (part number) and/or revision level for both
     a)   the affected Product currently installed or in service, and
     b)   the revised/updated Product to replace it.

5.   Associate Products or changes that must be applied in conjunction with or
     prior to this change.

6.   Detailed explanation of why change was necessary, and of the symptoms of
     the condition being corrected.

7.   Description of what to change, how to install change, and how to test or
     verify change.

8.   Effect of the change on the Product's service parameters, traffic handling,
     maintenance, reliability, technical/performance specifications, control and
     safety.

9.   Material/system Equipment affected by change, e.g., frame mounting, frame
     or inter-frame wiring, back planes, plug-in circuit packs, daughter boards,
     power, etc.

10.  Documents affected by change, e.g., system/unit/module descriptions,
     drawings, manuals, nomenclature, CLEI codes, ordering guides, etc.

11.  Modification implementation date, expiration date (for Class A changes),
     and cost of changes, where applicable.

Tekelec Business Confidential                                      Page 19 of 20

<PAGE>

                                             TEKELEC STANDARD PURCHASE AGREEMENT
                                                     Technical Assistance Center
                                                                      Appendix F

                       TEKELEC TECHNICAL ASSISTANCE CENTER

                           SERVICES AND RATE SCHEDULE

TEKELEC's Technical Assistance Center (TAC) provides a full range of services
for users of the TEKELEC Products. These services include Product Development
Planning and Validation, Product Delivery Assistance, Ongoing Customer Support
and Marketing Support.

Depending on the particular objective, TAC may provide on-site assistance or
support the Products remotely, through dial up access. Typically, TAC will
assist in the on-site turnover and execution of the Conformance Test Plan for
newly installed Products, at no additional charge. Thereafter, support is
provided via dial up access and telephone support. Additional on-site support
can be negotiated, as mutually agreed between the Buyer and TEKELEC.

Remote TAC assistance is available for:

     .    Problem Resolution

     .    Product Specific Technical Consultation

     .    Generic Software Load Installation and Turnover

     .    Interoperability Assistance

     .    Cutover Assistance

     .    Site Performance Audits

     .    Repair and Return Coordination

     .    Fault Isolation

When covered by either the Standard Warranty or the Custom Extended Warranty
Service, these remote services are provided at no charge.

When not covered by either the Standard Warranty or the Custom Extended Warranty
Service, or additional on-site assistance is required, the following rates
prevail:

     .    TAC telephone support services shall be billed at $175 per hour, with
          a minimum period of four (4) hours.

     .    If TAC personnel must be dispatched to the Buyer's site, the same
          hourly charges apply, plus travel and per diem expenses.

Tekelec Business Confidential                                      Page 20 of 20

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