Exhibit 10.1

EXECUTION COPY

        AMENDMENT NO. 4 TO THE
AMENDED AND RESTATED FIVE YEAR REVOLVING CREDIT FACILITY AGREEMENT

Dated as of February 6, 2004

        AMENDMENT NO. 4 TO THE AMENDED AND RESTATED FIVE YEAR REVOLVING CREDIT
FACILITY AGREEMENT among Avaya Inc., a Delaware corporation (the "Borrower"),
the banks, financial institutions and other institutional lenders parties to the
Credit Agreement referred to below (collectively, the "Lenders") and Citibank,
N.A., as agent (the "Agent") for the Lenders.

PRELIMINARY STATEMENTS:

        (1) The Borrower, the Lenders and the Agent have entered into an Amended
and Restated Five Year Revolving Agreement dated as of April 30, 2003, as
amended by Amendment No. 1 dated as of June 25, 2003, Amendment No. 2 dated as
of October 23, 2003 and Amendment No. 3 dated as of January 30, 2004 (as so
amended, the "Credit Agreement"). Capitalized terms not otherwise defined in
this Amendment have the same meanings as specified in the Credit Agreement.

        (2) The Borrower and the Required Lenders have agreed to amend the
Credit Agreement as hereinafter set forth.

        SECTION 1.    Amendment to Credit Agreement.    Section 5.19(xi) is
amended in full to read as follows:

        (xi) other Investments made after the January 30, 2004 in an aggregate
amount invested not to exceed $500,000,000, provided that: (1) immediately
before and after giving effect thereto, no Default or Event of Default shall
have occurred and be continuing or would result therefrom; (2) immediately after
giving effect to the acquisition of a company or business pursuant to this
clause (xi), the Borrower shall be in pro forma compliance with Section 5.08,
calculated based on the financial statements most recently delivered to the
Lenders pursuant to Section 5.02 and as though such acquisition had occurred at
the beginning of the four-quarter period covered thereby, (3) immediately before
and after giving effect thereto and to the repayment of any assumed Debt within
30 days after the consummation thereof, the Borrower has Unrestricted Domestic
Cash and Marketable Securities in an aggregate amount of not less than
$400,000,000, (4) immediately before and after giving effect thereto, no
Advances shall be outstanding hereunder, (5) the Borrower shall have pro forma
positive "Free Cash Flow" (as defined below) for the period of four fiscal
quarters most recently ended, calculated based on the financial statements most
recently delivered to the Lenders pursuant to Section 5.02 and as though such
Investment and any repayment of any assumed Debt in connection therewith had
occurred at the beginning of the four-quarter period covered thereby, (6) the
Borrower shall have a pro forma ratio of Debt to Consolidated EBITDA for the
period of four fiscal quarters most recently ended, calculated based on the
financial statements most recently delivered to the Lenders pursuant to
Section 5.02 and as though such Investment had occurred at the beginning of the
four-quarter period covered thereby, of no greater that the actual ratio of Debt
to Consolidated EBITDA for such period, calculated without giving effect to any
Excess Assumed Debt (as defined below), provided that, notwithstanding the
limitation set forth in this clause (6), the Borrower may assume Debt in excess
of the amount otherwise applicable under this clause (6) ("Excess Assumed Debt")
up to an aggregate principal amount of $200,000,000 after January 30, 2004 so
long as such Debt would be permitted as, and subject to the restrictions on,
reissued Debt under Section 5.17(B)(z), (7) any Debt assumed in connection with
such Investment (x) shall have a maturity date no earlier than 90 days after the
Maturity Date or (y) shall be repaid within 30 days after the consummation
thereof and (8) the Chief Financial Officer of the Borrower shall have delivered
to the Lenders a

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certificate as to the satisfaction of the conditions set forth in clauses
(1) through (7) above, including in reasonable detail the calculations necessary
for determination of the calculations required by clauses (2), (3), (5) and
(6) above, and certifying the total consideration to be paid for such
Investment. "Free Cash Flow" means net cash provided by (used for) operating
activities minus capital expenditures minus dividends, calculated based on the
financial statements delivered to the Lenders pursuant to Section 5.02.

        SECTION 2.    Conditions of Effectiveness.    This Amendment shall
become effective as of the date first above written when, and only when (a) the
Agent shall have received counterparts of this Amendment executed by the
Borrower and the Required Lenders or, as to any of the Lenders, advice
satisfactory to the Agent that such Lender has executed this Amendment and
(b) the Borrower shall have paid to the Agent any Fees and other amounts due and
payable on or prior to the date hereof.

        SECTION 3.    Representations and Warranties of the Borrower.    The
Borrower represents and warrants as follows:

        (a) It (i) is a corporation duly organized, validly existing and in good
standing under the laws of the jurisdiction of its organization, (ii) has all
requisite power and authority to own its property and assets and to carry on its
business as now conducted and as proposed to be conducted, (iii) is qualified to
do business in every jurisdiction where such qualification is required, except
where the failure so to qualify would not result in a Material Adverse Effect,
and (iv) has the corporate power and authority to execute, deliver and perform
its obligations under this Amendment.

        (b) The execution, delivery and performance by the Borrower of this
Amendment and the Loan Documents, as amended hereby, to which it is a party, and
the consummation of the transactions contemplated hereby (i) have been duly
authorized by all requisite corporate actions and (ii) will not (A) violate
(1) any provision of any law, statute, rule or regulation (including, without
limitation, the Margin Regulations) or of its certificate of incorporation or
other constitutive documents or by-laws, (2) any order of any Governmental
Authority or (3) any provision of any indenture, agreement or other instrument
to which it is a party or by which it or any of its property is or may be bound,
(B) be in conflict with, result in a breach of or constitute (alone or with
notice or lapse of time or both) a default under any such indenture, agreement
or other instrument or (C) except for the Liens created under the Collateral
Documents, result in the creation or imposition of any lien upon any of the
properties of the Borrower or any of its Subsidiaries.

        (c) This Amendment has been duly executed and delivered by the Borrower.
This Amendment and the Credit Agreement and the Notes, as amended hereby, are
the legal, valid and binding obligations of the Borrower, enforceable against
the Borrower in accordance with their respective terms.

        (d) No action, consent or approval of, registration or filing with or
any other action by any Governmental Authority is or will be required in
connection with the due execution, delivery, recordation, filing or performance
by the Borrower of this Amendment.

        (e) There are no actions or proceedings filed or (to its knowledge)
investigations pending or threatened against it in any court or before any
Governmental Authority or arbitration board or tribunal which question the
validity, enforceability or legality of or seek damages in connection with this
Amendment or the Credit Agreement and the Notes, as amended hereby, or any
action taken or to be taken pursuant to this Amendment or the Credit Agreement
and the Notes, as amended hereby, and no order or judgment has been issued or
entered restraining or enjoining it from the execution, delivery or performance
of this Amendment or the Credit Agreement and the Notes, as amended hereby, nor
is there any action or proceeding which involves a probable risk of an adverse
determination which would have any such effect; (ii) nor is there as of the date
hereof

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any other action or proceeding filed or (to its knowledge) investigation pending
or threatened against it in any court or before any Governmental Authority or
arbitration board or tribunal which involves a probable risk of a material
adverse decision which would result in a Material Adverse Effect, except as
provided in the Borrower's Annual Report on Form 10-K for the fiscal quarter
ended September 30, 2003, or materially restrict the ability of it to comply
with its obligations under this Amendment or the Credit Agreement and the Notes,
as amended hereby.

        (f) Prior to the date hereof, the Borrower has made Investments in the
Borrower's LYONs in an aggregate amount of not more than $140,000,000.

        SECTION 4.    Reference to and Effect on the Credit Agreement and the
Notes.    (a) On and after the effectiveness of this Amendment, each reference
in the Credit Agreement to "this Agreement", "hereunder", "hereof" or words of
like import referring to the Credit Agreement, and each reference in each other
Loan Document to "the Credit Agreement", "thereunder", "thereof" or words of
like import referring to the Credit Agreement, shall mean and be a reference to
the Credit Agreement, as amended by this Amendment.

        (b) The Credit Agreement and other Loan Documents, as specifically
amended by this Amendment, are and shall continue to be in full force and effect
and are hereby in all respects ratified and confirmed.

        (c) The execution, delivery and effectiveness of this Amendment shall
not, except as expressly provided herein, operate as a waiver of any right,
power or remedy of any Lender or the Agent under the Credit Agreement, nor
constitute a waiver of any provision of the Credit Agreement.

        SECTION 5.    Costs and Expenses.    The Borrower agrees to pay on
demand all costs and expenses of the Agent in connection with the preparation,
execution, delivery and administration, modification and amendment of this
Amendment and the other instruments and documents to be delivered hereunder
(including, without limitation, the reasonable fees and expenses of counsel for
the Agent) in accordance with the terms of Section 8.04 of the Credit Agreement.

        SECTION 6.    Execution in Counterparts.    This Amendment may be
executed in any number of counterparts and by different parties hereto in
separate counterparts, each of which when so executed shall be deemed to be an
original and all of which taken together shall constitute but one and the same
agreement. Delivery of an executed counterpart of a signature page to this
Amendment by telecopier shall be effective as delivery of a manually executed
counterpart of this Amendment.

        SECTION 7.    Governing Law.    This Amendment shall be governed by, and
construed in accordance with, the laws of the State of New York.

        IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
executed by their respective officers thereunto duly authorized, as of the date
first above written.

 
AVAYA INC.         By /s/  GARRY K. MCGUIRE      

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Title: Chief Financial Officer and Senior VP, Corporate Development      

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  CITIBANK, N.A., individually and as Agent,         By /s/  THOMAS
LABERGERE      

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Title: Director
Name: Thomas Labergere         BANK ONE, NA (Main Office Chicago)         By

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Title:
Name:         JPMORGAN CHASE BANK         By /s/  EDMOND DEFOREST      

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Title: Vice President
Name: Edmond DeForest         DEUTSCHE BANK AG NEW YORK BRANCH         By
/s/  DAVID DICKINSON      

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Title: Director
Name: David Dickinson         By /s/  PETER ESCHMANN      

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Title: Vice President
Name: Peter Eschman         COMMERZBANK AG, NEW YORK BRANCH         By

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Title:
Name:         By

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Title:
Name:         THE BANK OF NEW YORK         By

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Title:
Name:         THE BANK OF TOKYO—
MITSUBISHI LTD., NEW YORK BRANCH         By /s/  J. WILLIAM RHODES      

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Title: Authorized Signatory
Name: J. William Rhodes

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        CREDIT SUISSE FIRST BOSTON ACTING THROUGH ITS CAYMAN ISLANDS BRANCH    
    By /s/  PETER CHAUVIN      

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Title: Vice President
Name: Peter Chauvin         By /s/  ALAIN DAOUST      

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Title: Director
Name: Alain Daoust         HSBC BANK USA         By /s/  JEFFREY ROTHMAN      

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Title: Senior Vice President
Name: Jeffrey Rothman         THE NORTHERN TRUST COMPANY         By

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Title:
Name:         SUMITOMO MITSUI BANKING CORPORATION         By /s/  PETER R.C.
KNIGHT      

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Title: Joint General Manager
Name: Peter R.C. Knight         WESTDEUTSCHE LANDESBANK
GIROZENTRALE, NEW YORK BRANCH         By

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Title:
Name:

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