<PAGE>

                                                                     Exhibit 4.6

     INSTRUMENT OF RESIGNATION, APPOINTMENT AND ACCEPTANCE, dated as of January
__, 2001 (this "Instrument") among Motorola, Inc., a corporation duly organized
and existing under the laws of the State of Delaware, having its principal
office at 1303 East Algonquin Road, Schaumburg, Illinois 60196 (the "Company"),
Bank One Trust Company, N.A., a national banking association duly organized and
existing under the laws of the United States, having its principal Corporate
Trust Office at 1 Bank One Plaza, Chicago, Illinois 60670 ("Bank One" or
"Successor Trustee"), and BNY Midwest Trust Company (as successor trustee to
Harris Trust and Savings Bank), a banking corporation duly organized and
existing under the laws of the State of New York, having its principal office at
111 West Monroe Street, Chicago, Illinois 60603 (the "Resigning Trustee").

     WHEREAS:

     A.  The Company issued the securities described below (collectively, the
"Securities"):

5.80% Notes due October 15, 2008 of which $325,000,000 is outstanding;
7.625% Notes due November 15, 2010 of which $1,200,000,000 is outstanding;
7.5% Debentures due May 15, 2025 of which $400,000,000 is outstanding;
6.5% Debentures due September 1, 2025 of which $400,000,000 is outstanding;
5.22% Debentures due October 1, 2097 of which $300,000,000 is outstanding; and
6.5% Debentures due November 15, 2028 of which $445,000,000 is outstanding;

under the Indenture dated as of May 1, 1995 between the Company and the
Resigning Trustee (the "Indenture");

     B.  The Company appointed the Resigning Trustee as the paying agent (the
"Paying Agent") and the Security Registrar (the "Security Registrar") under the
Indenture;
<PAGE>

     C.  The Indenture provides that the Resigning Trustee may at any time
resign as Trustee, Paying Agent and Security Registrar by giving written notice
thereof to the Company;

     D.  The Resigning Trustee represents that it has given the Company written
notice of its resignation as Trustee, Paying Agent and Security Registrar, a
true copy of which is annexed hereto marked Exhibit A;

     E.  The Indenture further provides that, if the Trustee shall resign, the
Company shall promptly appoint a successor Trustee;

     F.  The Company by resolutions of a committee authorized by its Board of
Directors, a true copy of which is annexed to a Certificate of its Secretary or
Assistant Secretary annexed hereto and marked Exhibit B, accepted the
resignation of BNY Midwest Trust Company as Trustee, Paying Agent and Security
Registrar and appointed Bank One, as successor Trustee, Paying Agent and
Security Registrar;

     G.  The Indenture provides that the successor Trustee shall execute,
acknowledge and deliver to the Company and the Resigning Trustee an instrument
accepting such appointment and thereupon the resignation of the Resigning
Trustee shall become effective and Bank One, as such successor Trustee, without
any further act, deed or conveyance, shall become vested with all rights,
powers, duties and obligations of the Trustee;

     H.  The Indenture further provides that no successor Trustee shall accept
appointment as such unless at the time it is qualified and eligible under the
Indenture and the Trust Indenture Act of 1939 and the rules and regulations
promulgated thereunder (the "Trust Indenture Act");

     I.  Bank One is qualified, eligible and willing to accept such appointment
as successor Trustee; and

                                      -2-
<PAGE>

     J.  The Indenture further provides the Company shall mail notice of
appointment of a successor Trustee, Paying Agent and Security Registrar to
Holders of the Securities; and the Company, simultaneously with the execution
and delivery of this Instrument, has caused the notice required pursuant to the
Indenture, a form of which is annexed hereto and marked Exhibit C, to be mailed
to the Holders of the Securities as therein required.

     NOW, THEREFORE, THIS INSTRUMENT WITNESSETH: that for and in consideration
of the premises and of other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, it is hereby covenanted, declared,
decreed and agreed by the Company, Bank One and the Resigning Trustee as
follows:

     1.  The resignation of BNY Midwest Trust Company as Trustee, Paying Agent
and Security Registrar and its discharge from the trust created by the Indenture
shall be effective as of the date hereof upon the execution and delivery of this
Instrument by all the parties hereto.

     2.  The Company, in the exercise of the authority vested in it by the
Indenture, hereby appoints Bank One as successor Trustee, Paying Agent and
Security Registrar with all rights, powers, trusts, duties and obligations under
the Indenture, each such appointment to be effective as of the date hereof upon
the execution and delivery of this Instrument by all the parties hereto.

     3.  Bank One hereby represents that it is qualified and eligible under
the provisions of the Indenture and the Trust Indenture Act to be appointed
successor Trustee, Paying Agent and Security Registrar and hereby accepts its
appointment as successor Trustee, Paying Agent and Security Registrar effective
as of the date hereof upon the execution and delivery of this Instrument by all
parties hereto, and hereby assumes the rights, powers, trusts, duties and
obligations of the Trustee, Paying Agent and Security Registrar under the
Indenture, subject to all terms and provisions therein contained.

                                      -3-
<PAGE>

     4.  The Resigning Trustee hereby grants, gives, bargains, sells, remises,
releases, conveys, confirms, assigns, transfers and sets over to Bank One as
such successor Trustee, Paying Agent and Security Registrar and its successors
and assigns all rights, title and interest of the Resigning Trustee, as Trustee,
Paying Agent and Security Registrar in and to the trust estate and all rights,
powers and trusts, under the Indenture; and the Resigning Trustee as Trustee,
Paying Agent and Security Registrar does hereby agree to pay over, assign and
promptly deliver to Bank One as such successor Trustee, Paying Agent and
Security Registrar any and all money, if any, and property, if held by the
Resigning Trustee, as Trustee, Paying Agent and Security Registrar and the
Company for the purpose of more fully and certainly vesting in and confirming to
Bank One as such successor Trustee, Paying Agent and Security Registrar said
estate, properties, rights, powers and, at the request of Bank One, joins in the
execution hereof.

     5.  The Resigning Trustee hereby represents and warrants to the Successor
Trustee that:

        (a) No "Event of Default" (as defined in the Indenture) and no event
            which, after notice or lapse of time or both, would become an Event
            of Default, has occurred and is continuing under the Indenture;

        (b) No covenant or condition contained in the Indenture has been waived
            by the Resigning Trustee or by the Holders of the percentage in
            aggregate principal amount of the Securities required by the
            Indenture to effect any such waiver;

        (c) There is no action, suit, or proceeding pending or threatened
            against the Resigning Trustee before any court or governmental
            authority arising out of any action or omission by the Resigning
            Trustee as Trustee;

        (d) The Resigning Trustee has furnished, or as promptly as practicable
            will

                                      -4-
<PAGE>


            furnish, to the Successor Trustee originals of all documents
            relating to the trust created by the Indenture and all information
            in its possession relating to the administration and status thereof
            and will furnish to the successor Trustee any of such documents or
            information the Successor Trustee may select, provided that the
            Successor Trustee will make available to the Resigning Trustee as
            promptly as practicable following the request of the Resigning
            Trustee any such original documents which the Resigning Trustee may
            need to defend against any action, suit, or proceeding against the
            Resigning Trustee as Trustee or which the Resigning Trustee may need
            for any other proper purpose;

        (e) The Resigning Trustee has not delegated to any other party any of
            its duties as Trustee, Security Registrar, or Paying Agent, and has
            not appointed any Authenticating Agent; and

        (f) The Resigning Trustee has lawfully and fully discharged its duties
            as Trustee.

     6.  The Company hereby represents and warrants to the Successor Trustee
that:

        (a) It is a duly incorporated and existing corporation in good standing
            under the laws of the State of Delaware and has full power and
            authority to execute and deliver this Instrument;

        (b) This Instrument has been duly and validly authorized, executed, and
            delivered by the Company and constitutes a legal, valid, and binding
            obligation of the Company;

        (c) The Securities have been duly registered under the Securities Act
            of 1933, as

                                      -5-
<PAGE>

            amended, and such registration has become effective;

        (d) The Indenture complies with the Trust Indenture Act and has been
            duly qualified thereunder and is a legal, valid, and binding
            obligation of the Company;

        (e) The Company has performed or fulfilled each covenant, agreement, and
            condition on its part to be performed or fulfilled under the
            Indenture;

        (f) There is no "Event of Default" and no event which, after notice or
            lapse of time or both, would become an Event of Default under the
            Indenture;

        (g) The Company has not appointed any Security Registrar or Paying
            Agent other than the Resigning Trustee; and

        (h) The Company will continue to perform its obligations under the
            Indenture.

     7.  Notwithstanding the resignation of the Resigning Trustee as Trustee
under the Indenture, the Company shall remain obligated under the Indenture to
compensate, reimburse and indemnify the Resigning Trustee in connection with its
trusteeship under the Indenture.

     8.  For all purposes of this Instrument, except as otherwise expressly
provided or unless the context otherwise requires, all capitalized terms used
and not defined herein that are defined in the Indenture shall have the meanings
assigned to them in the Indenture.

     9.  This Instrument may be executed in any number of counterparts, each of
which shall be an original but such counterparts shall together constitute but
one and the same instrument.

     10.  This Instrument shall be governed by and construed in accordance with
the laws of the State of Illinois.

                            [signature pages follow]

                                      -6-
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this Instrument to be
duly executed and their respective seals to be affixed hereunto and duty
attested all as of the day and year first above written.

                                    MOTOROLA, INC.

                                    By:___________________________
                                          [Corporate Seal]

                                    Title:

                                    ATTEST:

                                    _____________________


                                    BANK ONE TRUST COMPANY, N.A.
                                    as Successor Trustee


                                    By:___________________________
                                          Title:
                                    [Corporate Seal]

                                    ATTEST:

                                    _____________________

                                      -7-
<PAGE>

                                    BNY MIDWEST TRUST COMPANY
                                    as Resigning Trustee

                                    By:___________________________
                                          Title:


                                    [Corporate Seal]

                                    ATTEST:

                                    _____________________

                                      -8-
<PAGE>

                                   EXHIBIT A





Motorola, Inc.
1303 East Algonquin Road
Schaumburg, Illinois 60196

Attention: Secretary

Gentlemen:

NOTICE IS HEREBY GIVEN THAT, pursuant to Section 610 of the Indenture, dated as
of May 1, 1995 (the "Indenture"), between Motorola, Inc. and BNY Midwest Trust
Company (as successor to Harris Trust and Savings Bank), as Trustee, BNY Midwest
Trust Company hereby resigns as Trustee, Paying Agent and Security Registrar
under the Indenture, each such resignation is to be effective upon the
appointment, pursuant to Section 610 of the Indenture, of a successor Trustee
and the acceptance of such appointment by such successor Trustee, pursuant to
Section 611 of the Indenture.

                                    Very truly yours,

                                    BNY Midwest Trust Company

                                    By________________________
                                    Title_______________________

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<PAGE>

                                   EXHIBIT B



                            CERTIFICATE OF SECRETARY
                            ------------------------


     I, ______________, do hereby certify that I am the duly appointed,
qualified and acting Secretary or Assistant Secretary of Motorola, Inc., a
Delaware corporation; I further certify that the resolution attached hereto as
Exhibit B-1 and incorporated herein by this reference, is a true and correct
copy of resolutions duly adopted by a committee authorized by the Board of
Directors of said corporation as of January ____, 2001; and I further certify
that said resolutions remain in full force and effect as of the date of this
certificate.

          Dated this __ day of January, 2001

                                    ________________________
                                    Title:

                                      -10-
<PAGE>

                                  EXHIBIT B.1


     RESOLVED, that the resignation of BNY Midwest Trust Company (as successor
to Harris Trust and Savings Bank), as Trustee, Paying Agent and Security
Registrar under an Indenture dated as of May 1, 1995 (the "Indenture") between
the Company, and BNY Midwest Trust Company (as successor to Harris Trust and
Savings Bank) in connection with the issuance of the Company's:

                        5.80% Notes due October 15, 2008
                         7.625% Notes due November 15,
                        7.5% Debentures due May 15, 2025
                     6.5% Debentures due September 1, 2025
                      5.22% Debentures due October 1, 2097
                     6.5% Debentures due November 15, 2028

is hereby accepted and Bank One Trust Company, N.A., a national banking
association, is hereby appointed as successor Trustee, Paying Agent and Security
Registrar under said Indenture; and

     FURTHER RESOLVED, that any officer of the Company is hereby authorized to
enter into such agreements as may be necessary to effectuate such appointment of
Bank One Trust Company, N.A.

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                                   EXHIBIT C

                             Notice to Holders of:

                                 MOTOROLA, INC.

                        5.80% Notes due October 15, 2008
                       7.625% Notes due November 15, 2010
                        7.5% Debentures due May 15, 2025
                     6.5% Debentures due September 1, 2025
                      5.22% Debentures due October 1, 2097
                     6.5% Debentures due November 15, 2028


Motorola, Inc. hereby notifies you of the resignation of BNY Midwest Trust
Company (as successor to Harris Trust and Savings Bank), as Trustee, Paying
Agent and Security Registrar under the Indenture dated as of May 1, 1995 (the
"Indenture"), pursuant to which your Securities were issued and are outstanding.

Motorola, Inc. has appointed Bank One Trust Company, N.A., whose Corporate Trust
Office is located at 1 Bank One Plaza, Chicago, Illinois 60670, as successor
Trustee, Paying Agent and Security Registrar under the Indenture, which
appointment has been accepted and became effective as of January __, 2001

MOTOROLA, INC.

By:______________________
Title:___________________

BANK ONE TRUST COMPANY, N.A.

By:______________________
Title:___________________

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