Document:

<PAGE>

                                                                     EXHIBIT 4.3

                          FIRST SUPPLEMENTAL INDENTURE

     FIRST SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"), dated as of
February 28, 2003, among the subsidiaries listed on Schedules A and B hereto
(each, a "Guaranteeing Subsidiary"), each a direct or indirect subsidiary of IPC
Acquisition Corp. (or its permitted successor), a Delaware corporation (the
"Company"), the Company, the other Guarantors (as defined in the Indenture
referred to herein) and The Bank of New York, as trustee under the indenture
referred to below (the "Trustee").

                              W I T N E S S E T H

     WHEREAS, the Company has heretofore executed and delivered to the Trustee
an indenture (the "Indenture"), dated as of December 20, 2001 providing for the
issuance of 11.50% Senior Subordinated Notes due 2009 (the "Notes");

     WHEREAS, the Indenture provides that under certain circumstances the
Guaranteeing Subsidiary shall execute and deliver to the Trustee a supplemental
indenture pursuant to which the Guaranteeing Subsidiary shall unconditionally
guarantee all of the Company's Obligations under the Notes and the Indenture on
the terms and conditions set forth herein (the "Subsidiary Guarantee"); and

     WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture.

     NOW THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the receipt of which is hereby acknowledged, the
parties mutually covenant and agree for the equal and ratable benefit of the
Holders of the Notes as follows:

     1.   CAPITALIZED TERMS.  Capitalized terms used herein without definition
shall have the meanings assigned to them in the Indenture.

     2.   AGREEMENT TO GUARANTEE.  The Guaranteeing Subsidiary hereby agrees as
follows:

               (a)  Along with all Guarantors named in this or other
          Supplemental Indentures, to jointly and severally Guarantee to each
          Holder of a Note authenticated and delivered by the Trustee and to the
          Trustee and its successors and assigns, the Notes or the obligations
          of the Company hereunder or thereunder, that:

               (i)  the principal of, and premium and Special Interest, if any,
          and interest on the Notes will be promptly paid in full when due,
          whether at maturity, by acceleration, redemption or otherwise, and
          interest on the overdue principal of and interest on the Notes, if
          any, if lawful, and all other obligations of the Company to the
          Holders or the Trustee hereunder or thereunder will be promptly paid
          in full or performed, all in accordance with the terms hereof and
          thereof; and

               (ii)  in case of any extension of time of payment or renewal of
          any Notes or any of such other obligations, that same will be promptly
          paid in full when due or performed in accordance with the terms of the
          extension or renewal, whether at stated maturity, by acceleration or
          otherwise. Failing payment when due of any amount so

                                       1
<PAGE>
          guaranteed or any performance so guaranteed for whatever reason, the
          Guarantors shall be jointly and severally obligated to pay the same
          immediately.

               (b)  The obligations hereunder shall be unconditional,
          irrespective of the validity, regularity or enforceability of the
          Notes or the Indenture, the absence of any action to enforce the same,
          any waiver or consent by any Holder of the Notes with respect to any
          provisions hereof or thereof, the recovery of any judgment against the
          Company, any action to enforce the same or any other circumstance
          which might otherwise constitute a legal or equitable discharge or
          defense of a Guarantor.

               (c)  The following is hereby waived: diligence, presentment,
          demand of payment, filing of claims with a court in the event of
          insolvency or bankruptcy of the Company, any right to require a
          proceeding first against the Company, protest, notice and all demands
          whatsoever.

               (d)  This Subsidiary Guarantee shall not be discharged except by
          complete performance of the obligations contained in the Notes and the
          Indenture, and the Guaranteeing Subsidiary accepts all obligations of
          a Guarantor under the Indenture.

               (e)  If any Holder or the Trustee is required by any court or
          otherwise to return to the Company, the Guarantors, or any custodian,
          trustee, liquidator or other similar official acting in relation to
          either the Company or the Guarantors, any amount paid by either to the
          Trustee or such Holder, this Subsidiary Guarantee, to the extent
          theretofore discharged, shall be reinstated in full force and effect.

               (f)  The Guaranteeing Subsidiary shall not be entitled to any
          right of subrogation in relation to the Holders in respect of any
          obligations guaranteed hereby until payment in full of all obligations
          guaranteed hereby.

               (g)  As between the Guarantors, on the one hand, and the Holders
          and the Trustee, on the other hand, (x) the maturity of the
          obligations guaranteed hereby may be accelerated as provided in
          Article 6 of the Indenture for the purposes of this Subsidiary
          Guarantee, notwithstanding any stay, injunction or other prohibition
          preventing such acceleration in respect of the obligations guaranteed
          hereby, and (y) in the event of any declaration of acceleration of
          such obligations as provided in Article 6 of the Indenture, such
          obligations (whether or not due and payable) shall forthwith become
          due and payable by the Guarantors for the purpose of this Subsidiary
          Guarantee.

               (h)  The Guarantors shall have the right to seek contribution
          from any non-paying Guarantor so long as the exercise of such right
          does not impair the rights of the Holders under the Subsidiary
          Guarantee.

               (i)  Each Guaranteeing Subsidiary, and by its acceptance of
          Notes, each Holder hereby confirms that it is the intention of all
          such parties that the Subsidiary Guarantee of such Guarantor not
          constitute a fraudulent transfer or conveyance for purposes of
          Bankruptcy Law, the Uniform Fraudulent Conveyance Act, the Uniform
          Fraudulent Transfer Act or any similar federal or state law to the
          extent applicable to any Subsidiary Guarantee. To effectuate the
          foregoing intention, the Trustee, the Holders and the Guarantors
          hereby irrevocably agree that the obligations of such Guarantor will,
          after giving effect to any maximum amount and all other contingent and
          fixed liabilities that are relevant under any applicable Bankruptcy or
          fraudulent conveyance laws, and after

                                       2

<PAGE>
          giving effect to any collections from, rights to receive contribution
          from or payments made by or on behalf of any other Guarantor in
          respect of the obligations of such other Guarantor under the
          Indenture, this new Subsidiary Guarantee shall be limited to the
          maximum amount permissible such that the obligations of such Guarantor
          under this Subsidiary Guarantee shall not constitute a fraudulent
          transfer or conveyance.

     3.   EXECUTION AND DELIVERY. Each Guaranteeing Subsidiary agrees that the
Subsidiary Guarantees shall remain in full force and effect notwithstanding any
failure to endorse on each Note a notation of such Subsidiary Guarantee.

     4.   GUARANTEEING SUBSIDIARY MAY CONSOLIDATE, ETC. ON CERTAIN TERMS.

               (a)  The Guaranteeing Subsidiary may not sell or otherwise
          dispose of all substantially all of its assets to, or consolidate with
          or merge with or into (whether or not such Guarantor is the surviving
          Person) another Person, other than the Company or another Guarantor
          unless:

               (i)  immediately after giving effect to such transaction, no
          Default or Event of Default exists; and

               (ii) either (A) subject to Section 11.06 of the Indenture, the
          Person acquiring the property in any such sale or disposition or the
          Person formed by or surviving any such consolidation or merger
          unconditionally assumes all the obligations of that Guarantor,
          pursuant to a supplemental indenture in form and substance reasonably
          satisfactory to the Trustee, under the Notes, the Indenture and the
          Subsidiary Guarantee on the terms set forth herein or therein; or
          (B) the Net Proceeds of such sale or other disposition are applied in
          accordance with the applicable provisions of the Indenture, including
          without limitation, Section 4.10 thereof.

               (b)  In case of any such consolidation, merger, sale or
          conveyance and upon the assumption of the successor Person, by
          supplemental indenture, executed and delivered to the Trustee and
          satisfactory in form to the Trustee, of the Subsidiary Guarantee
          endorsed upon the Notes and the due and punctual performance of all
          of the covenants and conditions of the Indenture to be performed by
          the Guarantor, such successor Person shall succeed to and be
          substituted for the Guarantor with the same effect as if it had been
          named herein as a Guarantor. Such successor Person thereupon may
          cause to be signed any or all of the Subsidiary Guarantees to be
          endorsed upon all of the Notes issuable under the Indenture which
          theretofore shall not have been signed by the Company and delivered
          to the Trustee. All the Subsidiary Guarantees so issued shall in all
          respects have the same legal rank and benefit under the Indenture as
          the Subsidiary Guarantees theretofore and thereafter issued in
          accordance with the terms of the Indenture as though all of such
          Subsidiary Guarantees had been issued at the date of the execution
          hereof.

               (c)  Notwithstanding the foregoing, a Guarantor may consolidate
          or merge with or into another Guarantor or into the Company, and the
          Company may consolidate or merge with or into a Guarantor.

                                       3
<PAGE>
     5.   RELEASES.

               (a)  In the event of any sale or other disposition of all or
          substantially all of the assets of any Guarantor, by way of merger,
          consolidation or otherwise, or a sale or other disposition of all of
          the capital stock of any Guarantor, in each case to a Person that is
          not (either before or after giving effect to such transaction) a
          Subsidiary of the Company or if the Company designates any Restricted
          Subsidiary that is a Guarantor as an Unrestricted Subsidiary in
          accordance with Section 4.18 of the Indenture, then such Guarantor
          (in the event of a sale or other disposition, by way of merger,
          consolidation or otherwise, of all of the capital stock of such
          Guarantor or designation as an Unrestricted Subsidiary) or the
          corporation acquiring the property (in the event of a sale or other
          disposition of all or substantially all of the assets of such
          Guarantor) shall be released and relieved of any obligations under its
          Subsidiary Guarantee; provided that the Net Proceeds of such sale or
          other disposition are applied in accordance with the applicable
          provisions of the Indenture, including without limitation Section 4.10
          of the Indenture. Upon delivery by the Company to the Trustee of an
          Officers' Certificate and an Opinion of Counsel to the effect that
          such sale or other disposition was made by the Company in accordance
          with the provisions of the Indenture, including without limitation
          Section 4.10 of the Indenture, the Trustee shall execute any documents
          reasonably required in order to evidence the release of any Guarantor
          from its obligations under its Subsidiary Guarantee.

               (b)  Any Guarantor not released from its obligations under its
          Subsidiary Guarantee shall remain liable for the full amount of
          principal of and interest on the Notes and for the other obligations
          of any Guarantor under the Indenture as provided in Article 11 of the
          Indenture.

     6.   NO RECOURSE AGAINST OTHERS. No past, present or future director,
officer, employee, incorporator, stockholder or agent of the Guaranteeing
Subsidiary, as such, shall have any liability for any obligations of the
Company or any Guaranteeing Subsidiary under the Notes, any Subsidiary
Guarantees, the Indenture or this Supplemental Indenture or for any claim based
on, in respect of, or by reason of, such obligations or their creation. Each
Holder of the Notes by accepting a Note waives and releases all such liability.
The waiver and release are part of the consideration for issuance of the Notes.

     7.   NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW YORK
SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE BUT WITHOUT
GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT
THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.

     8.   COUNTERPARTS. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

     9.   EFFECT OF HEADINGS. The Section headings herein are for convenience
only and shall not affect the construction hereof.

     10.  THE TRUSTEE. The Trustee shall not be responsible in any manner
whatsoever for or in respect of the validity or sufficiency of this
Supplemental Indenture or for or in respect of the recitals contained herein,
all of which recitals are made solely by the Guaranteeing Subsidiary and the
Company.

                                       4
<PAGE>
     IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed and attested, all as of the date first above
written.

     Dated: February 28, 2003

                              EACH GUARANTOR LISTED ON SCHEDULE A HERETO

                              By: /s/ Timothy Whelan
                                  ----------------------------------------------
                              Name:  Timothy Whelan
                              Title: Treasurer

                              EACH GUARANTOR LISTED ON SCHEDULE B HERETO

                              By: IPC Information Systems, Inc., its sole member

                              By: /s/ Timothy Whelan
                                  ----------------------------------------------
                              Name:  Timothy Whelan
                              Title: Treasurer

                              IPC ACQUISITION CORP.

                              By: /s/ Timothy Whelan
                                  ----------------------------------------------
                              Name:  Timothy Whelan
                              Title: Chief Financial Officer

                              EACH GUARANTOR LISTED ON SCHEDULE I HERETO

                              By: /s/ Timothy Whelan
                                  ----------------------------------------------
                              Name:  Timothy Whelan
                              Title: Treasurer

                              THE BANK OF NEW YORK, as Trustee

                              By: /s/ Dorothy Miller
                                  ----------------------------------------------
                                  Authorized Signatory

                                       5
<PAGE>
                                   Schedule A

IPC Information Systems Holdings, Inc.

IPC Information Systems Holdings USA, Inc.

IPC Information Systems Services, Inc.

                                       6
<PAGE>
                                   Schedule B

IPC Information Systems Holdings, L.L.C.

IPC Information Systems Holdings USA, L.L.C.

IPC Information Systems Services, L.L.C.

                                       7
<PAGE>
                                   Schedule I

IPC Information Systems, Inc.

IPC Funding Corp.

IPC Information Systems Far East, Inc.

V Band Corp.

                                       8<PAGE>
                                                                     EXHIBIT 4.4

                         SECOND SUPPLEMENTAL INDENTURE

     SECOND SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"), dated as of
May 13, 2003, among the subsidiaries listed on Schedule A hereto (each, a
"Guaranteeing Subsidiary"), each a director or indirect subsidiary of IPC
Acquisition Corp. (or its permitted successor), a Delaware corporation (the
"Company"), the Company, the other Guarantors (as defined in the Indenture
referred to herein) and The Bank of New York, as trustee under the indenture
referred to below (the "Trustee").

                              W I T N E S S E T H

     WHEREAS, the Company has heretofore executed and delivered to the Trustee
an indenture (the "Indenture"), dated as of December 20, 2001 providing for the
issuance of 11.50% Senior Subordinated Notes due 2009 (the "Notes");

     WHEREAS, the Indenture provides that under certain circumstances the
Guaranteeing Subsidiary shall execute and deliver to the Trustee a supplemental
indenture pursuant to which the Guaranteeing Subsidiary shall unconditionally
guarantee all of the Company's Obligations under the Notes and the Indenture on
the terms and conditions set forth herein (the "Subsidiary Guarantee"); and

     WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture.

     NOW THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the receipt of which is hereby acknowledged, the parties
mutually covenant and agree for the equal and ratable benefit of the Holders of
the Notes as follows:

     1.   CAPITALIZED TERMS. Capitalized terms used herein without definition
shall have the meanings assigned to them in the Indenture.

     2.   AGREEMENT TO GUARANTEE. The Guaranteeing Subsidiary hereby agrees to
as follows:

          (a)  Along with all Guarantors named in this or other Supplemental
     Indentures, to jointly and severally Guarantee to each Holder of a Note
     authenticated and delivered by the Trustee and to the Trustee and its
     successors and assigns, the Notes or the obligations of the Company
     hereunder or thereunder, that:

          (i)  the principal of, and premium and Special Interest, if any, and
     interest on the Notes will be promptly paid in full when due, whether at
     maturity, by acceleration, redemption or otherwise, and interest on the
     overdue principal of an interest on the Notes, if any, if lawful, and all
     other obligations of the Company to the Holders or the Trustee hereunder or
     thereunder will be promptly paid in full or performed, all in accordance
     with the terms hereof and thereof; and

          (ii) in case of any extension of time of payment or renewal of any
     Notes or any of such other obligations, that same will be promptly paid in
     full when due or performed in accordance with the terms of the extension or
     renewal, whether at stated maturity, by acceleration or otherwise. Failing
     payment when due of any amount so

                                       1

<PAGE>
guaranteed or any performance so guaranteed for whatever reason, the Guarantors
shall be jointly and severally obligated to pay the same immediately.

     (b)  The obligations hereunder shall be unconditional, irrespective of the
validity, regularity or enforceability of the Notes or the Indenture, the
absence of any action to enforce the same, any waiver or consent by any Holder
of the Notes with respect to any provisions hereof or thereof, the recovery of
any judgment against the Company, any action to enforce the same or any other
circumstance which might otherwise constitute a legal or equitable discharge or
defense of a Guarantor.

     (c)  The following is hereby waived: diligence, presentment, demand of
payment, filing of claims with a court in the event of insolvency or bankruptcy
of the Company, any right to require a proceeding first against the Company,
protest, notice and all demands whatsoever.

     (d)  This Subsidiary Guarantee shall not be discharged except by complete
performance of the obligations contained in the Notes and the Indenture, and the
Guaranteeing Subsidiary accepts all obligations of a Guarantor under the
Indenture.

     (e)  If any Holder or the Trustee is required by any court or otherwise to
return to the Company, the Guarantors, or any custodian, trustee, liquidator or
other similar official acting in relation to either the Company or the
Guarantors, any amount paid by either to the Trustee or such Holder, this
Subsidiary Guarantee, to the extent theretofore discharged, shall be reinstated
in full force and effect.

     (f)  The Guaranteeing Subsidiary shall not be entitled to any right of
subrogation in relation to the Holders in respect of any obligations guaranteed
hereby until payment in full of all obligations guaranteed hereby.

     (g)  As between the Guarantors, on the one hand, and the Holders and the
Trustee, on the other hand, (x) the maturity of the obligations guaranteed
hereby may be accelerated as provided in Article 6 of the Indenture for the
purposes of this Subsidiary Guarantee, notwithstanding any stay, injunction or
other prohibition preventing such acceleration in respect of the obligations
guaranteed hereby, and (y) in the event of any declaration of acceleration of
such obligations as provided in Article 6 of the Indenture, such obligations
(whether or not due and payable) shall forthwith become due and payable by the
Guarantors for the purpose of this Subsidiary Guarantee.

     (h)  The Guarantors shall have the right to seek contribution from any
non-paying Guarantor so long as the exercise of such right does not impair the
rights of the Holders under the Subsidiary Guarantee.

     (i)  Each Guaranteeing Subsidiary, and by its acceptance of Notes, each
Holder hereby confirms that it is the intention of all such parties that the
Subsidiary Guarantee of such Guarantor not constitute a fraudulent transfer or
conveyance for purposes of Bankruptcy Law, the Uniform Fraudulent Conveyance
Act, the Uniform Fraudulent Transfer Act or any similar federal or state law to
the extent applicable to any Subsidiary Guarantee. To effectuate the foregoing
intention, the Trustee, the Holders and the Guarantors hereby irrevocably agree
that the obligations of such Guarantor will, after giving effect to any maximum
amount and all other contingent and fixed liabilities that are relevant under
any applicable Bankruptcy or fraudulent conveyance laws, and after

                                       2
<PAGE>
          giving effect to any collections from, rights to receive contribution
          from or payments made by or on behalf of any other Guarantor in
          respect of the obligations of such other Guarantor under the
          Indenture, this new Subsidiary Guarantee shall be limited to the
          maximum amount permissible such that the obligations of such Guarantor
          under this Subsidiary Guarantee shall not constitute a fraudulent
          transfer or conveyance.

     3.   EXECUTION AND DELIVERY. Each Guaranteeing Subsidiary agrees that the
Subsidiary Guarantees shall remain in full force and effect notwithstanding any
failure to endorse on each Note a notation of such Subsidiary Guarantee.

     4.   GUARANTEEING SUBSIDIARY MAY CONSOLIDATE, ETC. ON CERTAIN TERMS.

               (a) The Guaranteeing Subsidiary may not sell or otherwise dispose
          of all substantially all of its assets to, or consolidate with or
          merge with or into (whether or not such Guarantor is the surviving
          Person) another person other than the Company or another Guarantor
          unless:

               (i)  immediately after giving effect to such transaction, no
          Default or Event of Default exists; and

               (ii) either (A) subject to Section 11.06 of the Indenture, the
          Person acquiring the property in any such sale or disposition or the
          Person formed by or surviving any such consolidation or merger
          unconditionally assumes all the obligations of that Guarantor,
          pursuant to a supplemental indenture in form and substance reasonably
          satisfactory to the Trustee, under the Notes, the Indenture and the
          Subsidiary Guarantee on the terms set forth herein or therein; or (B)
          the Net Proceeds of such sale or other disposition are applied in
          accordance with the applicable provisions of the Indenture, including
          without limitation, Section 4.10 thereof.

               (b) In case of any such consolidation, merger, sale or conveyance
          and upon the assumption by the successor Person, by supplemental
          indenture, executed and delivered to the Trustee and satisfactory in
          form to the Trustee, of the Subsidiary Guarantee endorsed upon the
          Notes and the due and punctual performance of all of the covenants and
          conditions of the Indenture to be performed by the Guarantor, such
          successor Person shall succeed to and be substituted for the Guarantor
          with the same effect as if it had been named herein as a Guarantor.
          Such successor Person thereupon may cause to be signed any or all of
          the Subsidiary Guarantees to be endorsed upon all of the Notes
          issuable under the Indenture which theretofore shall not have been
          signed by the Company and delivered to the Trustee. All the Subsidiary
          Guarantees so issued shall in all respects have the same legal rank
          and benefit under the Indenture as the Subsidiary Guarantees
          theretofore and thereafter issued in accordance with the terms of the
          Indenture as though all of such Subsidiary Guarantees had been issued
          at the date of the execution hereof.

               (c) Notwithstanding the foregoing, a Guarantor may consolidate
          or merge with or into another Guarantor or into the Company, and the
          Company may consolidate or merge with or into a Guarantor.

                                       3

<PAGE>
     5.   RELEASES.

               (a)  In the event of any sale or other disposition of all or
          substantially all of the assets of any Guarantor, by way of merger,
          consolidation or otherwise, or a sale or other disposition of all of
          the capital stock of any Guarantor, in each case to a Person that is
          not (either before or after giving effect to such transaction) a
          Subsidiary of the Company or if the Company designates any Restricted
          Subsidiary that is a Guarantor as an Unrestricted Subsidiary in
          accordance with Section 4.18 of the Indenture, then such Guarantor (in
          the event of a sale or other disposition, by way of merger,
          consolidation or otherwise, of all of the capital stock of such
          Guarantor or designation as an Unrestricted Subsidiary) or the
          corporation acquiring the property (in the event of a sale or other
          disposition of all or substantially all of the assets of such
          Guarantor) shall be released and relieved of any obligations under its
          Subsidiary Guarantee; provided that the Net Proceeds of such sale or
          other disposition are applied in accordance with the applicable
          provisions of the Indenture, including without limitation Section 4.10
          of the Indenture. Upon delivery by the Company to the Trustee of an
          Officers' Certificate and an Opinion of Counsel to the effect that
          such sale or other disposition was made by the Company in accordance
          with the provisions of the Indenture, including without limitation
          Section 4.10 of the Indenture, the Trustee shall execute any documents
          reasonably required in order to evidence the release of any Guarantor
          from its obligations under its Subsidiary Guarantee.

               (b)  Any Guarantor not released from its obligations under its
          Subsidiary Guarantee shall remain liable for the full amount of
          principal of and interest on the Notes and for the other obligations
          of any Guarantor under the Indenture as provided in Article 11 of the
          Indenture.

     6.   NO RECOURSE AGAINST OTHERS. No past, present or future director,
officer, employee, incorporator, stockholder or agent of the Guaranteeing
Subsidiary, as such, shall have any liability for any obligations of the
Company or any Guaranteeing Subsidiary under the Notes, any Subsidiary
Guarantees, the Indenture or this Supplemental Indenture or for any claim based
on, in respect of, or by reason of, such obligations or their creation. Each
Holder of the Notes by accepting a Note waives and releases all such liability.
The waiver and release are part of the consideration for issuance of the Notes.

     7.   NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW YORK
SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE BUT WITHOUT
GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT
THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.

     8.   COUNTERPARTS. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

     9.   EFFECT OF HEADINGS. The Section headings herein are for convenience
only and shall not affect the construction hereof.

     10.  THE TRUSTEE. The Trustee shall not be responsible in any manner
whatsoever for or in respect of the validity or sufficiency of this
Supplemental Indenture or for or in respect of the recitals contained herein,
all of which recitals are made solely by the Guaranteeing Subsidiary and the
Company.

                                       4
<PAGE>
     IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed and attested, all as of the date first above
written.

     Dated:  May 13, 2003

                                     EACH GUARANTOR LISTED ON SCHEDULE A HERETO

                                     By: /s/ Timothy Whelan
                                         --------------------------------------
                                         Name:  Timothy Whelan
                                         Title: Treasurer

                                     IPC ACQUISITION CORP.

                                     By: /s/ Timothy Whelan
                                         --------------------------------------
                                         Name:  Timothy Whelan
                                         Title: Chief Financial Officer

                                     EACH GUARANTOR LISTED ON SCHEDULE I HERETO

                                     By: /s/ Timothy Whelan
                                         --------------------------------------
                                         Name:  Timothy Whelan
                                         Title: Treasurer

                                     EACH GUARANTOR LISTED ON SCHEDULE II HERETO

                                     By: IPC Information Systems, Inc., its
                                         sole member

                                     By: /s/ Timothy Whelan
                                         --------------------------------------
                                         Name:  Timothy Whelan
                                         Title: Treasurer

                                     THE BANK OF NEW YORK,
                                     as Trustee

                                     By: /s/ Dorothy Miller
                                         --------------------------------------
                                         Authorized Signatory

                                       5

<PAGE>
                                   Schedule A

Gains Acquisition Corp.

Gains International (U.S.) Inc.

                                       6

<PAGE>
                                   Schedule I

IPC Information Systems, Inc.

IPC Funding Corp.

IPC Information Systems Far East, Inc.

V Band Corp.

IPC Information Systems Holdings, Inc.

IPC Information Systems Holdings USA, Inc.

IPC Information Systems Services, Inc.

                                       7
<PAGE>
                                  Schedule II

IPC Information Systems Holdings, L.L.C.

IPC Information Systems Holdings USA, L.L.C.

IPC Information Systems Services, L.L.C.

                                       8

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