<PAGE>

                                                                     EXHIBIT 4.3

================================================================================



                                   AVAYA INC.

                                       and

                            [NAME OF WARRANT AGENT],

                                  Warrant Agent




                           [FORM OF] WARRANT AGREEMENT

                           Dated as of          , 20__



================================================================================

<PAGE>

                              TABLE OF CONTENTS(1)


                                    ARTICLE I

                 ISSUANCE OF WARRANTS AND EXECUTION AND DELIVERY
                             OF WARRANT CERTIFICATES

<TABLE>
<CAPTION>
                                                                                 Page
<S>                <C>                                                           <C>

SECTION 1.01       Issuance of Warrants............................................1
SECTION 1.02       Execution and Delivery of Warrant Certificates..................2
SECTION 1.03       Issuance of Warrant Certificates................................3

                                   ARTICLE II

                WARRANT PRICE, DURATION AND EXERCISE OF WARRANTS

SECTION 2.01       Warrant Price...................................................3
SECTION 2.02       Duration of Warrants............................................3
SECTION 2.03       Exercise of Warrants............................................3


                                   ARTICLE III

                 OTHER PROVISIONS RELATING TO RIGHTS OF HOLDERS
                             OF WARRANT CERTIFICATES

SECTION 3.01       No Rights as a Holder of Warrant Notes Conferred by
                         Warrant or Warrant Certificates...........................4
SECTION 3.02       Lost, Stolen, Mutilated or Destroyed Warrant Certificates.......5
SECTION 3.03       Holder of Warrant Certificate May Enforce Rights................5


                                   ARTICLE IV

                  EXCHANGE AND TRANSFER OF WARRANT CERTIFICATE

SECTION 4.01       Exchange and Transfer of Warrant Certificates...................5
SECTION 4.02       Treatment of Holders of Warrant Certificates....................6
SECTION 4.03        Cancellation of Warrant Certificates...........................6
</TABLE>

--------
         (1) This table of contents shall not, for any purpose, be deemed to be
part of the Warrant Agreement.


                                       -i-
<PAGE>

<TABLE>
<CAPTION>
                                                                                 Page
<S>                <C>                                                           <C>
                                    ARTICLE V

                          CONCERNING THE WARRANT AGENT

SECTION 5.01       Warrant Agent..................................................7
SECTION 5.02       Conditions of Warrant Agent's Obligation.......................7
SECTION 5.03       Resignation and Appoint of Successor...........................8


                                   ARTICLE VI

                                  MISCELLANEOUS

SECTION 6.01       Amendment......................................................9
SECTION 6.02       Notice and Demands to the Company and Warrant Agent............10
SECTION 6.03       Addresses......................................................10
SECTION 6.04       Notices to Holders of Warrants.................................10
SECTION 6.05       Applicable Law.................................................10
SECTION 6.06       Delivery of Prospectus.........................................10
SECTION 6.07       Obtaining of Governmental Approvals............................11
SECTION 6.08       Persons Having Rights Under Warrant Agreement..................11
SECTION 6.09       Headings.......................................................11
SECTION 6.10       Counterparts...................................................11
SECTION 6.11       Inspection of Agreement........................................11

EXHIBIT A          Form of Warrant Certificate
[EXHIBIT B         Form of Certificate for Delivery of Bearer Warrant Notes]

</TABLE>


                                      -ii-
<PAGE>

                           FORM OF WARRANT AGREEMENT(2)

         WARRANT AGREEMENT dated as ___________________ of between Avaya Inc., a
Delaware corporation (the "Company", which term includes any successor
corporation under the Indenture hereinafter referred to), and as Warrant Agent
(the "Warrant Agent").

         WHEREAS the Company has entered into an Indenture dated as of
______________, 2001 (the "Indenture"), with The Bank of New York, as Trustee
(the Trustee, which term includes any successor trustee under the Indenture),
providing for the issuance from time to time of its unsecured debentures, notes
or other evidences of indebtedness (the "Notes"), to be issued in one or more
series; and

         WHEREAS, the Company proposes to sell [title of Notes being offered]
(the "Offered Notes") with warrant certificates evidencing one or more warrants
(the "Warrants" or, individually a "Warrant") representing the right to purchase
up to an aggregate principal amount of _________________ of [title of Notes
purchasable through exercise of Warrants] (the "Warrant Notes"), such Warrant
certificates and other warrant certificates issued pursuant to this Agreement
being herein called the "Warrant Certificates"(3); and

         WHEREAS, the Company desires the Warrant Agent to act on behalf of the
Company in connection with the issuance, exchange, exercise and replacement of
the Warrant Certificates, and in this Agreement wishes to set forth, among other
things, the form and provisions of the Warrant Certificates and the terms and
conditions on which they may be issued, exchanged, exercised and replaced;

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


                                    ARTICLE I

                       ISSUANCE OF WARRANTS AND EXECUTION
                      AND DELIVERY OF WARRANT CERTIFICATES

         SECTION 1.01. Issuance Of Warrants. Warrants shall be initially issued
in connection with the issuance of the Offered Notes [but shall be separately
transferable on and after ________________, 200_ (the "Detachable Date")] [and
shall not be separately transferable] and each Warrant Certificate shall
evidence one or more Warrants. Each

--------

         (2) The provisions of this Form will be completed or modified as
appropriate to reflect the terms of the Warrants. Offered Notes and the Warrant
Notes and the designation of the Warrant Agent. Monetary amounts may be in U.S.
dollars, in foreign denominated currency or in units based on or relating to
currencies.

         (3) If the Warrants are to be uncertificated, the provisions of this
Form will be modified as appropriate to reflect the terms of exercise and
transfer of uncertificated Warrants and other matters relating to the use of the
specified systems for uncertificated Warrants.

<PAGE>

Warrant evidenced thereby shall represent the right, subject to the provisions
contained herein and therein, to purchase a Warrant Note in the principal amount
of ___________________. Warrant Certificates shall be initially issued in units
with the Offered Notes and each Warrant Certificate included in such a unit
shall evidence Warrants for each _____________ principal amount of Offered Notes
included in such unit.

         SECTION 1.02. Execution and Delivery of Warrant Certificates. Warrant
Certificates, whenever issued, shall be in [bearer] [or] [registered] form [or
both] substantially in the form set forth in Exhibit A hereto, shall be dated
_______________ and may have such letters, numbers or other marks of
identification or designation and such legends or endorsements printed,
lithographed or engraved thereon as the officers of the Company executing the
same may approve (execution therefore to be conclusive evidence of such
approval) and as are not inconsistent with the provisions of this Agreement, or
as may be required to comply with any law or with any rule or regulation made
pursuant thereto or with any rule or regulation of any stock exchange on which
the Warrants may be listed, or to conform to usage. The Warrant Certificates
shall be signed on behalf of the Company by its Chairman of the Board of
Directors, its Vice-Chairman of the Board of Directors, its President, one of
its Vice Presidents, or its Treasurer, or an Assistant Treasurer under its
corporate seal reproduced thereon and attested by its Secretary or one of its
Assistant Secretaries. Such signatures may be manual or facsimile signatures of
such authorized officers and may be imprinted or otherwise reproduced on the
Warrant Certificates. The seal of the Company may be in the form of a facsimile
thereof and may be impressed, affixed imprinted or otherwise reproduced on the
Warrant Certificates.

         No Warrant Certificate shall be valid for any purpose, and no Warrant
evidenced thereby shall be exercisable, until such Warrant Certificate has been
countersigned by the manual signature or the Warrant Agent. Such signature by
the Warrant Agent upon any Warrant Certificate executed by the Company shall be
conclusive evidence that the Warrant Certificate so countersigned has been duly
issued hereunder.

         In case any officer of the Company who shall have signed any of the
Warrant Certificates shall cease to be such officer before the Warrant
Certificates so signed shall have been countersigned and delivered by the
Warrant Agent, such Warrant Certificates may be countersigned and delivered
notwithstanding that the person who signed such Warrant Certificates ceased to
be such officer of the Company; and any Warrant Certificate may be signed on
behalf of the Company by such persons as, at the actual date-of the execution of
such Warrant Certificate, shall be the proper officers of the Company, although
at the date of the execution of this Agreement any such person was not such
officer.

         [If bearer Warrants -- The term "holder" or "holder of a Warrant
Certificate" as used herein shall mean [If Offered Notes with Warrants which are
not immediately detachable -- prior to the Detachable Date, the registered owner
of the Offered Note to which such Warrant Certificate was initially attached (or
the bearer if the Offered Note is a bearer Note), and after such Detachable
Date] the bearer of such Warrant Certificate].]

         [If registered Warrants -- The term "holder" or "holder of a Warrant
Certificate" as used herein shall mean any person in whose name at the time any
Warrant Certificate shall be registered upon the books to be maintained by the
Warrant Agent for


                                      2
<PAGE>

that purpose [If Offered Notes with Warrants which are not immediately
detachable -- or, prior to the Detachable Date, upon the register of the Offered
Notes. The Company will, or will cause the register of the Offered Notes to,
make available at all times to the Warrant Agent such information as to holders
of the Offered Notes with Warrants as may be necessary to keep the Warrant
Agent's records up to date].]

         SECTION 1.03. Issuance of Warrant Certificates. Warrant Certificates
evidencing the right to purchase an aggregate principal amount not exceeding
__________________ of Warrant Notes (except as provided in Section 2.03(c), 3.02
and 4.01) may be executed by the Company and delivered to the Warrant Agent upon
the execution of this Warrant Agreement or from time to time thereafter. The
Warrant Agent shall upon receipt of Warrant Certificates duly executed on behalf
of the Company, countersign Warrant Certificates evidencing Warrants
representing the right to purchase up to ________________ aggregate principal
amount of Warrant Notes and shall deliver such Warrant Certificates to or upon
the order of the Company. Subsequent to such original issuance of the Warrant
Certificates, the Warrant Agent shall countersign a Warrant Certificate only if
the Warrant Certificate is issued in exchange or substitution for one or more
previously countersigned Warrant Certificates [If registered Warrants -- or in
connection with their transfer], as hereinafter provided or as provided in
Section 2.03(c).

                                   ARTICLE II

                WARRANT PRICE, DURATION AND EXERCISE OF WARRANTS

         SECTION 2.01. Warrant Price. During the period from and including
______________, 20__ to and including [ _____________, 20__] the exercise price
of each Warrant will be [% of the principal amount of the Warrant Notes] [ ]
plus [accrued amortization of the original issue discount] [accrued interest]
from the most recent preceding. [During the period from _____________, 20__, to
and including ______________, 20__, the exercise price of each Warrant will be [
% of the principal amount of the Warrant Notes] [ ] plus [accrued amortization
of the original issue discount] [accrued interest] from the most recently
preceding]. [In each case, the original issue discount will be amortized at a %
annual rate, computed on an annual basis using a 360-day year consisting of
twelve 30-day months.] Such purchase price of Warrant Notes is referred to in
this Agreement as the "Warrant Price". [The original issue discount for each
principal amount of Warrant Notes is .]

         SECTION 2.02. Duration of Warrants. Each Warrant may be exercised in
whole at any time, as specified herein, on or after the [date thereof][        ,
20__] and at or before 5:00 p.m. New York time on          , 20__, or such later
date as may be selected by the Company, in a written statement to the Warrant
Agent and with notice to the holders of Warrants (such date of expiration is
herein referred to as the "Expiration Date"). Each Warrant not exercised at or
before 5:00 p.m. New York time on the Expiration Date shall become void, and all
rights of the holder of the Warrant Certificate evidencing such Warrant under
this Agreement shall cease.

         SECTION 2.03. Exercise of Warrants.

         (a) During the period specified in Section 2.02 any whole number of
Warrants may be exercised [, subject to Section 2.03(c),] by delivery to the
Warrant Agent of the


                                     3
<PAGE>

Warrant Certificate evidencing such Warrant, with the form of election to
purchase Warrant Notes set forth on the reverse side of the Warrant Certificate
properly completed and duly executed, and by paying in full, [in lawful money of
the United States of America,] [in cash or by certified check or official bank
check or by bank wire transfer, in each case,] [by bank wire transfer] [in
immediately available funds], the Warrant Price for each Warrant exercised to
the Warrant Agent, such delivery and payment to be made at the corporate trust
office of the Warrant Agent [or a ]. The date on which the duly completed and
executed Warrant Certificate and payment in full of the Warrant Price is
received by the Warrant Agent shall be deemed to be the date on which the
Warrant is exercised. The Warrant Agent shall deposit all funds received by it
in payment of the Warrant Price in an account of the Company maintained with it
and shall advise the Company by telephone at the end of each day on which a
[payment] [wire transfer] for the exercise of Warrants is received of the amount
so deposited to its account. The Warrant Agent shall promptly confirm such
telephone advice to the Company in writing.

         (b) The Warrant Agent shall, from time to time, as promptly as
practicable, advise the Company and the Trustee, of (i) the number of Warrants
exercised, (ii) the instructions of each holder of the Warrant Certificates
evidencing such Warrants with respect to delivery of the Warrant Notes to which
such holder is entitled upon such exercise, (iii) delivery of Warrant
Certificates evidencing the balance, if any, of the Warrants remaining after
such exercise, and (iv) such other information as the Company or the Trustee
shall reasonably require.

         (c) As soon as practicable after the exercise of any Warrant, the
Company shall issue, pursuant to the Indenture, in authorized denominations to
or upon the order of the holder of the Warrant Certificate evidencing such
Warrant, the Warrant Notes to which such holder is entitled, [in fully
registered form, registered in such name or names] [or] [in bearer form] as may
be directed by such holder[; provided, however, the Company shall deliver
Warrant Notes in bearer form only outside the United States and only upon
delivery from the person entitled to physical delivery of such Warrant Notes of
an executed certification substantially in the form of Exhibit B hereto.] If
less than all of the Warrants evidenced by such Warrant Certificate are
exercised, the Company shall execute, and an authorized officer of the Warrant
Agent shall manually countersign and deliver, a new Warrant Certificate
evidencing the number of such Warrants remaining unexercised.

         (d) The Company shall not be required to pay any stamp or other tax or
other governmental charge required to be paid in connection with any transfer
involved in the issuance of the Warrant Notes and the Company shall not be
required to issue or deliver any Warrant Note unless and until the person
requesting the issuance thereof shall have paid to the Company the amount of
such tax or governmental charge or shall have established to the satisfaction of
the Company that such tax or other governmental charge has been paid or that no
such tax or other governmental charge is payable.

                                   ARTICLE III

                     OTHER PROVISIONS RELATING TO RIGHTS OF
                         HOLDERS OF WARRANT CERTIFICATES

         SECTION 3.01. No Rights as a Holder of Warrant Notes Conferred by
Warrants or Warrant Certificates. No Warrant Certificate or Warrant evidenced
thereby


                                        4
<PAGE>

shall entitle the holder thereof to any of the rights of a holder of Warrant
Notes, including, without limitation, the right to receive the payment of
principal of, premium, if any, or interest on Warrant Notes or to enforce any of
the covenants in the Indenture.

         SECTION 3.02. Lost, Stolen, Mutilated or Destroyed Warrant
Certificates. Upon receipt by the Warrant Agent of evidence reasonably
satisfactory to it of the ownership of and the loss, theft, destruction or
mutilation of any Warrant Certificate and an indemnity reasonably satisfactory
to it and, in the case of mutilation, upon surrender of such Warrant Certificate
to the Warrant Agent for cancellation, then, in the absence of notice to the
Company or the Warrant Agent that such Warrant Certificate has been acquired by
a bona fide purchaser or holder in due course, the Company may (or, in the case
of mutilation, shall) execute, and in such event an authorized officer of the
Warrant Agent shall manually countersign and deliver, in exchange for or in lieu
of the lost, stolen, destroyed or mutilated Warrant Certificate, a new Warrant
Certificate of the same tenor and evidencing a like number of Warrants. Upon the
issuance of any new Warrant Certificate under this Section, the Company may
require the payment of a sum sufficient to cover any tax or other governmental
charge that may be imposed in relation thereto and any other expenses (including
the fees and expenses of the Warrant Agent) in connection therewith. Every
substitute Warrant Certificate executed and delivered pursuant to this Section
in lieu of any lost, stolen or destroyed Warrant Certificate shall represent an
additional contractual obligation of the Company, whether or not the lost,
stolen or destroyed Warrant Certificate shall be at any time enforceable by
anyone, and shall be entitled to the benefits of this Agreement equally and
proportionately with any and all other Warrant Certificates duly executed and
delivered hereunder. The provisions of this section are exclusive and shall
preclude (to the extent lawful) any and all other rights and remedies
notwithstanding any law or statute existing or hereinafter enacted to the
contrary with respect to the replacement or payment of negotiable instruments or
other securities without their surrender.

         SECTION 3.03. Holder of Warrant Certificate May Enforce Rights.
Notwithstanding any of the provisions of this Agreement, any holder of a Warrant
Certificate without the consent of the Warrant Agent, the Trustee, the holder of
any Warrant Notes or the holder of any other Warrant Certificate, may, in his
own behalf and for his own benefit, enforce, and may institute and maintain any
suit, action or proceeding against the Company suitable to enforce or otherwise
in respect of, his right to exercise the Warrants evidenced by his Warrant
Certificate in the manner provided in his Warrant Certificate and in this
Agreement.

                                   ARTICLE IV

                  EXCHANGE AND TRANSFER OF WARRANT CERTIFICATE

         SECTION 4.01. Exchange and Transfer of Warrant Certificates. [If
offered Notes with Warrants which are immediately detachable -- Upon] [If
Offered Notes with Warrants which are not immediately detachable --Prior to the
Detachable Date a Warrant Certificate may be exchanged or transferred only
together with the Offered Note to which the Warrant Certificate was initially
attached, and only for the purpose of effecting or in conjunction with an
exchange or transfer of such Offered Note. Prior to the Detachable Date, each
transfer of the Offered Note [on the register of the Offered Notes; shall
operate also to transfer the related Warrant Certificates. After the Detachable
Date upon]


                                        5
<PAGE>

surrender at the corporate trust office of the Warrant Agent [or ___], Warrant
Certificates evidencing Warrants may be exchanged for Warrant Certificates in
other denominations evidencing such Warrants [If registered Warrants -- or the
transfer may be registered in whole or in part]; provided that such other
Warrant Certificates evidence a like number of Warrants as the Warrant
Certificates so surrendered. [If registered and bearer Warrants (subject to any
limitations imposed with respect to such exchanges) -- [After the Detachable
Date, upon] [Upon] surrender at the corporate trust office of the Warrant Agent
[or ___] Warrant Certificates in bearer form may be exchanged for Warrant
Certificates in registered form evidencing a like number of Warrants.] [If
registered Warrants -- The Warrant Agent shall keep, at its corporate trust
office [and at ___], books in which, subject to such reasonable regulations as
it may prescribe, it shall register Warrant Certificates and exchanges and
transfers to outstanding Warrant Certificates, upon surrender of the Warrant
Certificates to the Warrant Agent at its corporate trust office [or
______________] for exchange [or registration of transfer], properly endorsed or
accompanied by appropriate instruments of registration of transfer and written
instructions for transfer, all in form satisfactory to the Company and the
Warrant Agent. No service charge shall be made for any exchange or registration
of transfer] of Warrant Certificates, but the Company may require payment of a
sum sufficient to cover any stamp or other tax or other governmental charge that
may be imposed in connection with any such exchange [or registration of
transfer]. Whenever any Warrant Certificates are so surrendered for exchange or
registration of transfer, an authorized officer of the Warrant Agent shall
manually countersign and deliver to the person or persons entitled thereto a
Warrant Certificate or Warrant Certificates duly authorized and executed by the
Company, as so requested. The Warrant Agent shall not be required to effect any
exchange [or registration of transfer] which will result in the issuance of a
Warrant Certificate evidencing a fraction of a Warrant [or a number of full
Warrants and a fraction of a Warrant]. All Warrant Certificates issued upon any
exchange [or registration of transfer] of Warrant Certificates shall be the
valid obligations of the Company evidencing the same obligations, and entitled
to the some benefits under this Agreement, as the Warrant Certificate
surrendered for such exchange [or registration of transfer].

         SECTION 4.02. Treatment of Holders Warrant Certificates. [If Offered
Notes with bearer Warrants which are not immediately detachable ---Subject to
Section 4.01, each] [If Offered Notes with bearer Warrants which are immediately
detachable -- Each] Warrant Certificate shall be transferable by delivery and
shall be deemed negotiable and the bearer of each Warrant Certificate may be
treated by the Company, the Warrant Agent and all other persons dealing with
such bearer as the absolute owner thereof for any purpose and as the person
entitled to exercise the rights represented by the Warrants evidenced thereby,
any notice to the contrary notwithstanding.] [If registered Warrant -- Every
holder of a Warrant Certificate, by accepting the same, consents and agrees with
the Company, the Warrant Agent and with every subsequent holder of such Warrant
Certificate that until the transfer of the Warrant Certificate is registered on
the books of the Warrant Agent [or the register of the Offered Notes prior to
the Detachable Date], the Company and the Warrant Agent [or the registrar of the
Offered Notes prior to the Detachable Date] may treat such registered holder as
the absolute owner thereof for any purpose and as the person entitled to
exercise the rights represented by the Warrants evidenced thereby, any notice to
the contrary notwithstanding.]

         SECTION 4.03. Cancellation of Warrant Certificates. Any Warrant
Certificate surrendered for exchange [, registration of transfer] or exercise of
the Warrants evidenced thereby shall, if surrendered to the Company, be
delivered to the Warrant Agent and all Warrant Certificates surrendered or so
delivered to the Warrant Agent shall be promptly


                                        6
<PAGE>

canceled by the Warrant Agent and shall not be reissued and, except as expressly
permitted by this Agreement, no Warrant Certificate shall be issued hereunder in
exchange or in lieu thereof. The Warrant Agent shall deliver to the Company from
time to time or otherwise dispose of cancelled Warrant Certificates in a manner
satisfactory to the Company.

                                    ARTICLE V

                          CONCERNING THE WARRANT AGENT

         SECTION 5.01. Warrant Agent. The Company hereby appoints as Warrant
Agent of the Company in respect of the Warrants and the Warrant Certificates
upon the terms and subject to the conditions herein set forth; and
_______________ hereby accepts such appointment. The Warrant Agent shall have
the powers and authority granted to and conferred upon it in the Warrant
Certificates and hereby and such further powers and authority to act on behalf
of the Company as the Company may hereafter grant to or confer upon it. All of
the terms and provisions with respect to such powers and authority contained in
the Warrant Certificates are subject to and governed by the terms and provisions
hereof.

         SECTION 5.02. Conditions of Warrant Agent's Obligations. The Warrant
Agent accepts its obligations herein set forth upon the terms and conditions
hereof, including the following, to all of which the Company agrees and to all
of which the rights hereunder of the holders from time to time of the Warrant
Certificates shall be subject:

         (a) Compensation and Indemnification. The Company agrees promptly to
pay the Warrant Agent the compensation to be agreed upon with the Company for
all services rendered by the Warrant Agent and to reimburse the Warrant Agent
for reasonable out-of-pocket expenses (including counsel fees) incurred by the
Warrant Agent in connection with the services rendered hereunder by the Warrant
Agent. The Company also agrees to indemnify the Warrant Agent for, and to hold
it harmless against, any loss, liability or expense incurred, without negligence
or bad faith on the part of the Warrant Agent, arising out of or in connection
with its action as Warrant Agent hereunder, as well as the costs and expenses of
defending against any claim of such liability.

         (b) Agent for the Company. In acting under this Warrant Agreement and
in connection with the Warrant Certificates, the Warrant Agent is acting solely
as agent of the Company and does not assume any obligation or relationship of
agency or trust for or with any of the holders of Warrant Certificates or
beneficial owners of Warrants.

         (c) Counsel. The Warrant Agent may consult with counsel satisfactory to
it, and the advice of such counsel shall be full and complete authorization and
protection in respect of any action taken, suffered or omitted by it hereunder
in good faith and in accordance with the advice of such counsel.

         (d) Documents. The Warrant Agent shall be protected and shall incur no
liability for or in respect of any action taken or thing suffered by it in
reliance upon any Warrant Certificate, notice, direction, consent, certificate,
affidavit, statement or other paper or document reasonably believed by it to be
genuine and to have been presented or signed by the proper parties.


                                        7
<PAGE>

         (e) Certain Transactions. The Warrant Agent, and its officers,
directors and employees, may become the owner of, or acquire any interest in,
Warrants, with the same rights that it or they would have if it were not the
Warrant Agent hereunder, and, to the extent permitted by applicable law, it or
they may engage or be interested in any financial or other transaction with the
Company and may act on, or as depositary, trustee or agent for, any committee or
body of holders of Warrant Notes or other obligations of the Company as freely
as if it were not the Warrant Agent hereunder. Nothing in this Warrant Agreement
shall be deemed to prevent the Warrant Agent from acting as Trustee under the
Indenture.

         (f) No Liability for Invalidity. The Warrant Agent shall have no
liability with respect to any invalidity of this Agreement or any of the Warrant
Certificates.

         (g) No Liability for Interest. The Warrant Agent shall have no
liability for interest on any monies at any time received by it pursuant to any
of the provisions of this Agreement or of the Warrant Certificates.

         (h) No Responsibility for Representations. The Warrant Agent shall not
be responsible for any of the recitals or representations herein or in the
Warrant Certificates (except as to the Warrant Agent's countersignature
thereon), all of which are made solely by the Company.

         (i) No Implied Obligations. The Warrant Agent shall be obligated to
perform only such duties as are herein and in the Warrant Certificates
specifically set forth and no implied duties or obligations shall be read into
this Agreement or the Warrant Certificates against the Warrant Agent. The
Warrant Agent shall not be under any obligation to take any action hereunder
which may tend to involve it in any expense or liability, the payment of which
within a reasonable time is not, in its reasonable opinion, assured to it. The
Warrant Agent shall not be accountable or under any duty or responsibility for
the use by the Company of any of the Warrant Certificates authenticated by the
Warrant Agent and delivered by it to the Company pursuant to this Agreement or
for the application by the Company of the proceeds of the Warrant Certificates.
The Warrant Agent shall have no duty or responsibility in case of any default by
the Company in the performance of its covenants or agreements contained herein
or in the Warrant Certificates or in the case of the receipt of any written
demand from a holder of a Warrant Certificate with respect to such default,
including, without limiting the generality of the foregoing, any duty or
responsibility to initiate or attempt to initiate any proceedings at law or
otherwise or, except as provided in Section 6.02 hereof, to make any demand upon
the Company.

         SECTION 5.03. Resignation and Appointment of Successor.

         (a) The Company agrees, for the benefit of the holders from time to
time of the Warrant Certificates, that there shall at all times be a Warrant
Agent hereunder until all the Warrant Certificates are no longer exercisable.

         (b) The Warrant Agent may at any time resign as such agent by giving
written notice to the Company of such intention on its part, specifying the date
on which its desired resignation shall become effective; provided that such date
shall not be less than three months after the date on which such notice is given
unless the Company otherwise agrees. The Warrant Agent hereunder may be removed
at any time by the filing with it of an instrument in writing signed by or on
behalf of the Company and specifying such removal and the date when it shall
become effective. Such resignation or removal shall take effect upon the
appointment by the Company, as hereinafter provided, of a successor


                                        8
<PAGE>

Warrant Agent (which shall be a bank or trust company authorized under the laws
of the jurisdiction of its organization to exercise corporate trust powers) and
the acceptance of such appointment by such successor Warrant Agent. The
obligation of the Company under Section 5.02(a) shall continue to the extent set
forth therein notwithstanding the resignation or removal of the Warrant Agent.

         (c) In case at any time the Warrant Agent shall resign, or shall be
removed, or shall become incapable of acting, or shall be adjudged a bankrupt or
insolvent, or shall file a petition seeking relief under the Federal Bankruptcy
Code, as now constituted or hereafter amended, or under any other applicable
Federal or state bankruptcy law or similar law or make an assignment for the
benefit of its creditors or consent to the appointment of a receiver or
custodian of all or any substantial part of its property, or shall admit in
writing its inability to pay or meet its debts as they mature, or if a receiver
or custodian of it or of all or any substantial part of its property shall be
appointed, or if an order of any court shall be entered for relief against it
under the provisions of the Federal Bankruptcy Code, as now constituted or
hereafter amended, or under any other applicable Federal or state bankruptcy or
similar law, or if any public officer shall have taken charge or control of the
Warrant Agent or of its property or affairs, for the purpose of rehabilitation,
conservation or liquidation, a successor Warrant Agent, qualified as aforesaid,
shall be appointed by the Company by an instrument in writing, filed with the
successor Warrant Agent. Upon the appointment as aforesaid of a successor
Warrant Agent and acceptance by the successor Warrant Agent of such appointment,
the Warrant Agent shall cease to be Warrant Agent hereunder.

         (d) Any successor Warrant Agent appointed thereunder shall execute,
acknowledge and deliver to its predecessor and to the Company an instrument
accepting such appointment hereunder, and hereupon such successor Warrant Agent,
without any further act, deed or conveyance, shall become vested with all the
authority, rights, powers, trusts, immunities, duties and obligations of such
predecessor with like effect as if originally named as Warrant Agent hereunder,
and such predecessor, upon payment of its charges and disbursements then unpaid,
shall thereupon become obligated to transfer, deliver and pay over, and such
successor Warrant Agent shall be entitled to receive, all monies, securities and
other property on deposit with or held by such predecessor, as Warrant Agent
hereunder.

         (e) Any corporation into which the Warrant Agent hereunder may be
merged or converted or any corporation with which the Warrant Agent may be
consolidated, or any corporation resulting from any merger, conversion or
consolidation to which the Warrant Agent shall be a party, or any corporation to
which the Warrant Agent shall sell or otherwise transfer all or substantially
all the assets and business of the Warrant Agent, provided that it shall be
qualified as aforesaid, shall be the successor Warrant Agent under this
Agreement without the execution or filing of any paper or any further act on the
part of any of the parties hereto.

                                   ARTICLE VI

                                  MISCELLANEOUS

         SECTION 6.01. Amendment. This Agreement may be amended by the parties
hereto, without the consent of the holder of any Warrant Certificate, for the
purpose of curing any ambiguity, or of curing, correcting or supplementing any
defective provision


                                        9

<PAGE>

contained herein, or making any other provisions with respect to matters or
questions arising under this Agreement as the Company and the Warrant Agent may
deem necessary or desirable; provided that such action shall not adversely
affect the interests of the holders of the Warrant Certificates.

         SECTION 6.02. Notices and Demands to the Company and Warrant Agent. If
the Warrant Agent shall receive any notice or demand addressed to the Company by
the holder of a Warrant Certificate pursuant to the provisions of the Warrant
Certificates, the Warrant Agent shall promptly forward such notice or demand to
the Company.

         SECTION 6.03. Addresses. Any communication from the Company to the
Warrant Agent with respect to this Agreement shall be addressed to
______________, Attention: _______________, and any communication from the
Warrant Agent to the Company with respect to this Agreement shall be addressed
to Avaya Inc., Attention: ______________,[ADDRESS] (or such other address as
shall be specified in writing by the Warrant Agent or by the Company).

         SECTION 6.04. Notices to Holders of Warrants. Any notice to holders of
Warrants which by any provisions of this Warrant Agreement is required or
permitted to be given shall be given [If registered Warrants -- by first class
mail postage prepaid at such holder's address as appears on the books of the
Warrant Agent [or on the register of the Offered Notes prior to the Detachable
Date]] [If bearer Warrants -- by publication in an Authorized Newspaper in New
York City and London [, and so long as the Warrants are listed on the Luxembourg
Stock Exchange and the Luxembourg Stock Exchange so requires, in Luxembourg.] As
used herein, the term "Authorized Newspaper" means a newspaper customarily
published on each business day in morning editions, whether or not it shall be
published in Saturday, Sunday or holiday editions, such as the Wall Street
Journal (Eastern edition) in New York City, the Financial Times (London edition)
in London and the Luxemburger Wort in Luxembourg. If by reason of the temporary
or permanent suspension of publication of any newspaper or by reason of any
other cause, it shall be impossible to make publication of such notices in an
Authorized Newspaper as herein required, then such publication or other notice
in lieu thereof as shall be made by the Warrant Agent shall constitute
sufficient publication of such notice, if such publication or other notice
shall, so far as may be possible, approximate the terms and conditions of the
publication in lieu of which it is given. The Warrant Agent shall promptly
furnish to the Company a copy of each notice so published.]

         SECTION 6.05. Applicable Law. The validity, interpretation and
performance of this Agreement and each Warrant Certificate issued hereunder and
of the respective terms and provisions thereof shall be governed by, and
construed in accordance with, the laws of the State of New York applicable to
agreements made and to be performed therein.

         SECTION 6.06. Delivery of Prospectus. The Company will furnish to the
Warrant Agent sufficient copies of a prospectus with an accompanying prospectus
supplement relating to the Warrant Notes, and the Warrant Agent agrees that upon
the exercise of any Warrant, the Warrant Agent will deliver to the holder of the
Warrant Certificate evidencing such Warrant, prior to or concurrently with the
delivery of the Warrant Notes issued upon such exercise, a copy of such
prospectus and prospectus supplement.


                                       10
<PAGE>

         SECTION 6.07. Obtaining of Governmental Approvals. The Company will
from time to time take all action which may be necessary to obtain and keep
effective any and all permits, consents and approvals of governmental agencies
and authorities and securities acts filings under United States Federal and
state laws (including without limitation a registration statement in respect of
the Warrants and Warrant Note under the Securities Act of 1933), which may be or
become requisite in connection with the issuance, sale, transfer and delivery of
the Warrant Certificates, the exercise of the Warrants, the issuance, sale,
transfer and delivery of the Warrant Notes issued upon exercise of the Warrants
or upon the expiration of the period during which the Warrants are exercisable.

         SECTION 6.08. Persons Having Rights Under Warrant Agreement. Nothing in
this Agreement shall give to any person other than the Company, the Warrant
Agent (and, subject to this Agreement, their successors and assigns) and the
holders of the Warrant Certificates any right, remedy or claim under or by
reason of this Agreement.

         SECTION 6.09. Headings. The descriptive headings of the several
Articles and Sections of this Agreement are inserted for convenience only and
shall not control or affect the meaning or construction of any of the provisions
hereof.

         SECTION 6.10. Counterparts. This Agreement may be executed in any
number of counterparts, each of which as so executed shall be deemed to be an
original, but such counterparts shall together constitute but one and the same
instrument.

         SECTION 6.11. Inspection of Agreement. A copy of this Agreement shall
be available at all reasonable times at the principal corporate trust office of
the Warrant Agent for inspection by the holder of any Warrant Certificate. The
Warrant Agent may require such holder to submit his Warrant Certificate for
inspection by it.


                                       11
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
signed by one of their respective authorized officers as of the day and year
first above written.

                                             AVAYA INC.


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


                                             [NAME OF WARRANT AGENT],
                                             as Warrant Agent


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


                                       12
<PAGE>

                                    EXHIBIT A

                          [FORM OF WARRANT CERTIFICATE]

         [Face of Warrant Certificate]

[Form of Legend if Notes with Warrants which are not immediately detachable:
Prior to ____________, 20__, this Warrant Certificate cannot be transferred or
exchanged unless attached to a [Title of Offered Notes].]

                EXERCISABLE ONLY IF COUNTERSIGNED BY THE WARRANT
                            AGENT AS PROVIDED HEREIN

                                   AVAYA INC.

                              WARRANTS TO PURCHASE
                            [Title of Warrant Notes]

                VOID AFTER 5 P.M. NEW YORK TIME ON _______, 20__
No.

         This certifies that [the bearer is the] [ ___________________ or
registered assigns is the registered] owner of the above indicated number of
Warrants, each Warrant entitling such [bearer] [registered owner] to purchase,
at any time [after 5 P.M. New York time on _____________, 20__ and] on or before
5 P.M. New York time on _____________, 20__ (or such later date as may be
selected by the Company with notice to the holder thereof as provided in the
Warrant Agreement (as hereinafter defined)), $_________ principal amount of
[Title of Warrant Notes] (the "Warrant Notes"), of Avaya Inc., a Delaware
corporation (Avaya Inc. and any successor corporation under the Indenture
hereinafter defined being hereinafter referred to as the "Company"), to be
issued under the Indenture (as hereinafter defined) on the following basis:
during the period from and including _____________, 20__, to and including
_______________, 20__, the exercise price of each Warrant will by [__% of the
principal amount of the Warrant Notes] [$___] plus [accrued amortization of the
original issue discount] [accrued interest] from the most recently preceding
_____________; during the period from _________________, 20__, to and including
_____________, 20__, the exercise price of each Warrant will be __% of the
principal amount of the Warrant Notes] [$______] plus [accrued amortization of
the original issue discount] [accrued interest] from the most recently preceding
_____________; [in each case, the original issue discount will be amortized at a
___% annual rate, computed on an annual basis, using a 360-day year consisting
of twelve 30-day months] (the "Warrant Price"). [The original issue discount for
each $________ principal amount of Warrant Notes is $__________.] The holder may
exercise the Warrants evidenced hereby by delivery to the Warrant Agent (as
hereinafter defined) or this Warrant Certificate, with the form of election to
purchase on the reverse hereof properly completed and duly executed and by
paying in full [in lawful money of the United States of America,] [in cash or by
certified check or official bank check or by bank wire transfer, in each case,]
[by bank wire transfer] [in immediately available funds,] the Warrant Price for
each Warrant exercised to the Warrant Agent, such delivery and payment to be
made at the corporate trust office of [name of Warrant Agent], or its successor
as warrant agent (the "Warrant Agent"), [or _____________________] currently at
the address specified on the reverse hereof, and upon compliance with and
subject to the conditions set forth herein and in the Warrant Agreement (as
hereinafter defined).

<PAGE>

         Any whole number of Warrants evidenced by this Warrant Certificate may
be exercised to purchase Warrant Notes [in registered form in denominations of
$_____________ and any integral multiples thereof] [in bearer form in the
denomination of $___________] [or both]. Upon any exercise of less than all of
the Warrants evidenced by this Warrant Certificate, there shall be issued to the
holder hereof a new Warrant Certificate evidencing the number of Warrants
remaining unexercised.

         This Warrant Certificate is issued under and in accordance with the
Warrant Agreement dated as of 20__ (the "Warrant Agreement") between the Company
and the Warrant Agent and is subject to the terms and provisions contained in
the Warrant Agreement, to all of which terms and provisions the holder of this
Warrant Certificate consents by acceptance hereof. Copies of the Warrant
Agreement are on file at the above- mentioned office of the Warrant Agent [and
at __________________].

         The Warrant Notes to be issued and delivered upon the exercise of the
Warrants evidenced by this Warrant Certificate will be issued under and in
accordance with an Indenture dated as of ___________ , 2001 (the "Indenture"),
between the Company and The Bank of New York, as Trustee (The Bank of New York
and any successor to such Trustee being hereinafter referred to as the
"Trustee"), and will be subject to the terms and provisions contained in the
Indenture. Copies of the Indenture and the form of the Warrant Notes are on file
at the corporate trust office of the Trustee [and at ______________].

         [If Offered Notes with bearer Warrants which are not immediately
detachable - - Prior to ____________, 20__, this Warrant Certificate may be
exchanged or transferred only together with the [Title of Offered Notes] (the
"Offered Notes") to which this Warrant Certificate was initially attached, and
only for the purpose of effecting, or in conjunction with, an exchange or
transfer of such Offered Notes. After such date, this] [If Offered Notes with
bearer Warrants which are immediately detachable -- This] Warrant Certificate,
and all rights hereunder, may be transferred by delivery and the Company and the
Warrant Agent may treat the bearer hereof as the owner for all purposes.]

         [If Offered Notes with registered Warrants which are not immediately
detachable -- Prior to ________________ 20__, this Warrant Certificate may be
exchanged or transferred only together with the [Title of Offered Notes] (the
"Offered Notes") to which this Warrant Certificate was initially attached, and
only for the purpose of effecting, or in conjunction with, an exchange or
transfer of such Offered Notes. After such date, this] [If Offered Notes with
registered Warrants which are immediately detachable -- Transfer of this]
Warrant Certificate may be registered when this Warrant Certificate is
surrendered at the corporate trust office of the Warrant Agent [or _________] by
the registered owner or his assigns, in person or by an attorney duly authorized
in writing, in the manner and subject to the limitations provided in the Warrant
Agreement.]

         [If Offered Notes with Warrants which are not immediately detachable --
Except as provided in the immediately preceding paragraph, after] [If Offered
Notes with bearer Warrants which are immediately detachable -- After]
countersignature by the Warrant Agent and prior to the expiration of this
Warrant Certificate, this Warrant Certificate may be exchanged at the corporate
trust office of the Warrant Agent for Warrant Certificates, representing the
same aggregate number of Warrants, [in registered form] [in bearer form] [its
either registered or bearer form].


                                        2
<PAGE>

         This Warrant Certificate shall not entitle the holder hereof to any of
the rights of a holder of the Warrant Notes, including, without limitation, the
right to receive payments of principal of, or premium, if any, or interest, if
any, on the Warrant Notes or to enforce any of the covenants of the Indenture.

         This Warrant Certificate shall not be valid or obligatory for any
purpose until countersigned by the Warrant Agent.

Dated as of  , 20__.


                                             AVAYA INC.


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

[Name of Warrant Agent]

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


                                        3

<PAGE>

                        [REVERSE OF WARRANT CERTIFICATE]
                      INSTRUCTIONS FOR EXERCISE OF WARRANT

         To exercise the Warrants evidenced hereby, the holder must pay [in cash
or by certified check or official bank check or by bank wire transfer] [by bank
wire transfer] [in immediately available funds] the Warrant Price in full for
Warrants exercised to [insert name of Warrant Agent] Corporate Trust Department,
[insert address of Warrant Agent], Attn. _________________ [or
_________________] which [payment] [wire transfer] must specify the name of the
holder and the number of Warrants exercised by such holder. In addition, the
holder must complete the information required below and present this Warrant
Certificate in person or by mail (registered mail is recommended) to the Warrant
Agent at the addresses set forth below. This Warrant Certificate, completed and
duly executed, must be received by the Warrant Agent together with such
[payment] [wire transfer]. [If the undersigned is requesting delivery of Warrant
Notes in bearer form, the person entitled to physical delivery of such Warrant
Notes will be required to deliver a certificate (copies of which may be obtained
from the Warrant Agent [or ________________] certifying that such Warrant Notes
are not being acquired by or on behalf of a U.S. person or for resale to a U.S.
person unless such U.S. person is a qualified financial institution as defined
under United States tax laws and regulations.]


                                        4
<PAGE>

                     TO BE EXECUTED UPON EXERCISE OF WARRANT

         The undersigned hereby irrevocably elects to exercise Warrants,
evidenced by this Warrant Certificate, to purchase $__________ principal amount
of the [Title of Warrant Notes] (the "Warrant Notes") of Avaya Inc. and
represents that he has tendered payment for such Warrant Notes [in cash or by
certified check or official bank check or by bank wire transfer, in each case,]
[by bank wire transfer] [in immediately available funds] to the order of Avaya
Inc. c/o [insert name and address of Warrant Agent], in the amount of $________
in accordance with the terms hereof. The undersigned requests that said
principal amount of Warrant Notes be in [bearer form in the authorized
denominations] [fully registered form in the authorized denominations,
registered in such names aid delivered] all as specified in accordance with the
instructions set forth below.

         If the number of Warrants exercised is less than all of the Warrants
evidenced hereby, the undersigned requests that a new Warrant Certificate
representing the remaining Warrants evidenced hereby be issued and delivered to
the undersigned, unless otherwise specified ;n the instructions below.


Dated:                                      Name
      ---------------------------               -----------------------------
       (Please Print)

                                            Address                      (Insert
---------------------------------                  ----------------------
Social Security or
other Identifying Number of
Holder)
       --------------------------
Signature
         ------------------------

         The Warrants evidenced hereby may be exercised at the following
addresses:

By hand at:
       -------------------------------------------------------------

       -------------------------------------------------------------

       -------------------------------------------------------------

       -------------------------------------------------------------

By mail at
           ---------------------------------------------------------------------

           ---------------------------------------------------------------------

           ---------------------------------------------------------------------

           ---------------------------------------------------------------------

         [Instructions as to form and delivery of Warrant Notes and, if
applicable, Warrant Certificates evidencing unexercised Warrants -- complete as
appropriate.]


                                        5
<PAGE>

                             [If Registered Warrant]

                                   Assignment

              (Form of Assignment To Be Executed If Holder Desires
                     To Transfer Warrants Evidenced Hereby)

FOR VALUE RECEIVED _________________________ hereby sells, assigns and
transfers unto

                     Please insert social security or other
                               identifying number


         (Please print name and address including zip code)


of the Warrants represented by the within Warrant Certificate and does hereby
irrevocably constitute and appoint _______________ Attorney, to transfer said
Warrant Certificate on the books of the Warrant Agent with full power of
substitution in the premises.

Dated:

                                    ------------------------------
                                            Signature

                                    (Signature must conform in all respects to
                                    name of holder as specified on the face of
                                    this Warrant Certificate and must bear a
                                    signature guarantee by a bank, trust company
                                    or member broker of the New York, Midwest or
                                    Pacific Stock Exchange.)

Signature Guaranteed:


----------------------------


                                                    6
<PAGE>

                                    EXHIBIT B

            FORM OF CERTIFICATE FOR DELIVERY OF BEARER WARRANT NOTES

                                   AVAYA INC.

[Title of Warrant Notes]

To:    Avaya Inc.
       c/o ______________________,
       as Trustee

         This certificate is submitted in connection with the undersigned's
request that you deliver to us $_________ principal amount of [Title of Warrant
Notes] (the "Warrant Notes") in bearer form upon exercise of Warrants.

         The undersigned hereby certifies that as of the date hereof (the date
of delivery to the undersigned of the Warrant Notes), the Warrant Notes which
are to be delivered to the undersigned in bearer form are not being acquired,
directly or indirectly, by or on behalf of a U.S. person, or for offer to resell
or for resale to a U.S. person or any person inside the U.S. or, if any
beneficial owner of the Warrant Notes is a U.S. person such U.S. person is a
financial institution (as defined below) or acquiring through a financial
institution. If the undersigned is a clearing organization, the undersigned
represents that this certificate is based on statements provided to it by its
member organizations. If the undersigned is a dealer, the undersigned agrees to
obtain a similar certificate from each person entitled to delivery of any of the
Warrant Notes in bearer form purchased from it.

         Notwithstanding the foregoing, if the undersigned has actual
knowledge that the information contained in such certificate is false, the
undersigned will not deliver a Warrant Note in bearer form to the person who
signed such certificate notwithstanding the delivery of such certificate to
the undersigned. The undersigned will be deemed to have actual knowledge that
the beneficial owner is a U.S. person for this purpose if the undersigned has
a United States address for the beneficial owner of the Security and does not
have documentary evidence that the beneficial owner is not a U.S. person. As
used herein, "United States" means the United States of America (including
the States and the District of Columbia), its territories, its possessions
and other areas subject to its jurisdiction; "U.S. person" means any citizen
or resident of the United States, a corporation, partnership or other entity
created or organized under the laws of the United States or any political
subdivision thereof, or an estate or trust the income of which is subject to
United States federal income taxation regardless of its source; "financial
institution" means a branch located outside the United States of a financial
institution as defined in Section 1.165-12(c)(1)(v) of the Treasury
Department Regulations purchasing for its own account or for the account of a
customer that agrees in writing to comply with Section 165(j)(3)(A), (B) or
(C) of the Internal Revenue Code of 1986 and the regulations thereunder and
that is not purchasing for offer to resell or for resale in the United
States; and a "clearing organization" means an entity which is in the
business of holding obligations for member organizations and transferring
obligations among such members by credit or debit to the account of a member
without the necessity of physical delivery of the obligation.

         We understand that this certificate is required in connection with
United States tax laws and regulations. We irrevocably authorize you to
produce this certificate or a


<PAGE>

copy hereof to any interested party in any administrative or legal proceedings
with respect to the matters covered by this certificate.


                                    ------------------------------
                                            Signature

                                    ------------------------------
                                        (Please print name)

Dated:


Address:


                                        2