Document:

<PAGE>   1
                                                                     Exhibit 4.8

                           NEXTEL INTERNATIONAL, INC.,
                                                   as Issuer

                                       and

                              THE BANK OF NEW YORK,
                                              as Trustee

                                   ----------

                          First Supplemental Indenture

                          Dated as of December 13, 2000

                                    ---------

                                       To

                The Indenture dated as of March 12, 1998 between
         Nextel International, Inc. and The Bank of New York, as Trustee
   relating to $730,000,000 Aggregate Principal Amount at Maturity (originally
              issued) of 12.125% Senior Discount Notes due 2008

<PAGE>   2

               THIS FIRST SUPPLEMENTAL INDENTURE (the "Supplemental Indenture")
is made as of the 13th day of December, 2000, between NEXTEL INTERNATIONAL,
INC., a Washington corporation (the "Company"), NEXTEL INTERNATIONAL, INC., a
Delaware corporation ("NII Delaware") and THE BANK OF NEW YORK, a New York
banking corporation (the "Trustee").

                             RECITALS OF THE COMPANY

               WHEREAS, the Company and the Trustee have heretofore executed and
delivered an Indenture, dated as of March 12, 1998 (the "Indenture");

               WHEREAS, pursuant to the Indenture, the Company originally issued
$730,000,000 in aggregate principal amount of its 12.125% Senior Discount Notes
due 2008 (the "Notes");

               WHEREAS, contemporaneously herewith, the Company is merging (the
"Merger"), with and into NII Delaware, a wholly-owned subsidiary of the Company,
pursuant to an Agreement of Merger by and between NII Delaware and the Company
(the "Agreement of Merger"), whereby NII Delaware will be the surviving
corporation following the Merger;

               WHEREAS, the stated purpose for such Merger is to change the
state of incorporation of the Company from the state of Washington to the state
of Delaware;

               WHEREAS, Section 9.01(ii) of the Indenture provides that the
Company (when authorized by a resolution of its Board of Directors) and the
Trustee may enter into an indenture or indentures supplemental to the Indenture
for the purpose of complying with Article Five of the Indenture without the
necessity of receiving consent from the holders of the Notes;

               WHEREAS, Section 5.01 of the Indenture allows a merger of the
Company for the purpose of changing its state of incorporation if (a) the entity
that is the continuing Person following the merger expressly agrees to assume
the obligations of the Indenture and the Notes, (b) no Default or Event of
Default has occurred or is continuing as a result of the merger and (c) the
Company delivers to the Trustee an Officers Certificate and Opinion of Counsel
stating that the merger and the supplemental indenture comply with the Indenture
and that all conditions precedent to the merger and to the execution of the
supplemental indenture have been complied with;

               WHEREAS, this Supplemental Indenture has been duly authorized by
all necessary corporate action on the part of the Company;

               WHEREAS, the Company has delivered, or caused to be delivered, to
the Trustee, an Officers' Certificate and Opinion of Counsel stating that the
Merger and this Supplemental Indenture comply with the requirements of the
Indenture and that all conditions precedent to the Merger and to the execution
of the Supplemental Indenture have been complied with; and

               NOW THEREFORE, the Company and NII Delaware hereby covenant and
agree with the Trustee for the equal and proportionate benefit of all holders of
the Notes as follows:

<PAGE>   3

                                  ARTICLE ONE
                            ASSUMPTION OF OBLIGATIONS

               Section 1.01. NII Delaware hereby expressly assumes all of the
obligations of the Company on all of the Notes issued under the Indenture and
under the Indenture.

               Section 1.02. Each occurrence of the term "Company" in the
Indenture shall hereinafter refer to Nextel International, Inc., a Delaware
corporation, as successor to Nextel International, Inc., a Washington
corporation.

               Section 1.03. Pursuant to Section 5.02 of the Indenture, NII
Delaware is hereby substituted for, and may exercise every right and power of,
the Company under the Indenture with the same effect as if NII Delaware had been
named as the Company therein, and hereafter the Company, as the predecessor
corporation, shall be relieved of all obligations and covenants under this
Indenture and the Notes.

                                  ARTICLE TWO
                            MISCELLANEOUS PROVISIONS

               Section 2.01. Effect of Supplemental Indenture. Upon the
execution and delivery of this Supplemental Indenture by the Company, NII
Delaware and the Trustee, as of the Effective Time the Indenture shall be
supplemented in accordance herewith and this Supplemental Indenture shall form a
part of the Indenture for all purposes, and every holder of Notes heretofore or
hereafter authenticated and delivered under the Indenture shall be bound
thereby.

               Section 2.02. Indenture Remains in Full Force and Effect. Except
as supplemented hereby, all provisions in the Indenture shall remain in full
force and effect.

               Section 2.03. Confirmation and Preservation of Indenture. The
Indenture as supplemented by this Supplemental Indenture is in all respects
confirmed and preserved.

               Section 2.04. Indenture and Supplemental Indenture Construed
Together. This Supplemental Indenture is an indenture supplemental to and in
implementation of the Indenture, and the Indenture and this Supplemental
Indenture shall henceforth be read and construed together.

               Section 2.05. Conflict with Trust Indenture Act. If any provision
of this Supplemental Indenture limits, qualifies or conflicts with any provision
of the Trust Indenture Act (the "TIA") that is required under the TIA to be part
of and govern any provision of this Supplemental Indenture, the provision of the
TIA shall control. If any provision of this Supplemental Indenture modifies or
excludes any provision of the TIA that may be so modified or excluded, the
provision of the TIA shall be deemed to apply to the Indenture as so modified or
to be excluded by this Supplemental Indenture, as the case may be.

               Section 2.06. Separability Clause. In case any provision in this
Supplemental Indenture shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or impaired thereby.

<PAGE>   4

               Section 2.07. Terms Defined in the Indenture. All capitalized
terms not otherwise defined herein shall have the meanings ascribed to them in
the Indenture.

               Section 2.08. Effect of Headings. The Article and Section
headings herein are for convenience only and shall not affect the construction
hereof.

               Section 2.09. Benefits of Supplemental Indenture, etc. Nothing in
this Supplemental Indenture, the Indenture or the Notes, express or implied,
shall give to any Person, other than the parties hereto and thereto and their
successors hereunder and thereunder and the holders of Notes, any benefit of any
legal or equitable right, remedy or claim under the Indenture, this Supplemental
Indenture or the Notes.

               Section 2.10. Successors and Assigns. All covenants and
agreements in this Supplemental Indenture by the Company shall bind its
successors and assigns, whether so expressed or not.

               Section 2.11. Trustee Not Responsible for Recitals. The recitals
contained herein shall be taken as the statements of the Company and NII
Delaware, and the Trustee assumes no responsibility for their correctness.

               Section 2.12. Certain Duties and Responsibilities of the Trustee.
In entering into this Supplemental Indenture, the Trustee shall be entitled to
the benefit of every provision of the Indenture relating to the conduct or
affecting the liability of or affording protection to the Trustee, whether or
not elsewhere herein so provided.

               Section 2.13. Governing Law. This Supplemental Indenture shall be
governed by and construed in accordance with the laws of the State of New York,
without regard to the conflicts of law principles thereof.

               Section 2.14. Counterparts. This Supplemental Indenture may be
executed in counterparts, each of which, when so executed, shall be deemed to be
an original, but all such counterparts shall together constitute but one and the
same instrument.

<PAGE>   5

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

                                    NEXTEL INTERNATIONAL, INC., a
                                    Washington corporation

                                    By: /s/ ROBERT J. GILKER
                                       ----------------------------------------
                                    Name:  Robert J. Gilker
                                    Title:  Vice President and General Counsel

                                    NEXTEL INTERNATIONAL, INC., a
                                    Delaware corporation

                                    By: /s/ ROBERT J. GILKER
                                       ----------------------------------------
                                    Name:  Robert J. Gilker
                                    Title:  Vice President and General Counsel

                                    THE BANK OF NEW YORK, as Trustee

                                    By: /s/ MARY LAGUMINA
                                       ----------------------------------------
                                    Name:  Mary LaGumina
                                    Title:  Vice President<PAGE>   1
                                                                     Exhibit 4.9

                           NEXTEL INTERNATIONAL, INC.,
                                                   as Issuer

                                       and

                              THE BANK OF NEW YORK,
                                              as Trustee

                                   ----------

                          First Supplemental Indenture

                          Dated as of December 13, 2000

                                    ---------

                                       To

                The Indenture dated as of August 1, 2000 between
         Nextel International, Inc. and The Bank of New York, as Trustee
   relating to $650,000,000 Aggregate Principal Amount at Maturity (originally
                issued) of 12.75% Senior Serial Notes due 2010

<PAGE>   2

               THIS FIRST SUPPLEMENTAL INDENTURE (the "Supplemental Indenture")
is made as of the 13th day of December, 2000, between NEXTEL INTERNATIONAL,
INC., a Washington corporation (the "Company"), NEXTEL INTERNATIONAL, INC., a
Delaware corporation ("NII Delaware") and THE BANK OF NEW YORK, a New York
banking corporation (the "Trustee").

                             RECITALS OF THE COMPANY

               WHEREAS, the Company and the Trustee have heretofore executed and
delivered an Indenture, dated as of August 1, 2000 (the "Indenture");

               WHEREAS, pursuant to the Indenture, the Company originally issued
$650,000,000 in aggregate principal amount of its 12.75% Senior Serial Notes due
2010 (the "Notes");

               WHEREAS, contemporaneously herewith, the Company is merging (the
"Merger"), with and into NII Delaware, a wholly-owned subsidiary of the Company,
pursuant to an Agreement of Merger by and between NII Delaware and the Company
(the "Agreement of Merger"), whereby NII Delaware will be the surviving
corporation following the Merger;

               WHEREAS, the stated purpose for such Merger is to change the
state of incorporation of the Company from the state of Washington to the state
of Delaware;

               WHEREAS, Section 9.01(2) of the Indenture provides that the
Company (when authorized by a resolution of its Board of Directors) and the
Trustee may enter into an indenture or indentures supplemental to the Indenture
for the purpose of complying with Article Five of the Indenture without the
necessity of receiving consent from the holders of the Notes;

               WHEREAS, Section 5.01 of the Indenture allows a merger of the
Company for the purpose of changing its state of incorporation if (a) the entity
that is the continuing Person following the merger expressly agrees to assume
the obligations of the Indenture and the Notes, (b) no Default or Event of
Default has occurred or is continuing as a result of the merger and (c) the
Company delivers to the Trustee an Officers Certificate and Opinion of Counsel
stating that the merger and the supplemental indenture comply with the Indenture
and that all conditions precedent to the merger and to the execution of the
supplemental indenture have been complied with;

               WHEREAS, this Supplemental Indenture has been duly authorized by
all necessary corporate action on the part of the Company;

               WHEREAS, the Company has delivered, or caused to be delivered, to
the Trustee, an Officers' Certificate and Opinion of Counsel stating that the
Merger and this Supplemental Indenture comply with the requirements of the
Indenture and that all conditions precedent to the Merger and to the execution
of the Supplemental Indenture have been complied with; and

               NOW THEREFORE, the Company and NII Delaware hereby covenant and
agree with the Trustee for the equal and proportionate benefit of all holders of
the Notes as follows:

<PAGE>   3

                                  ARTICLE ONE
                            ASSUMPTION OF OBLIGATIONS

               Section 1.01. NII Delaware hereby expressly assumes all of the
obligations of the Company on all of the Notes issued under the Indenture and
under the Indenture.

               Section 1.02. Each occurrence of the term "Company" in the
Indenture shall hereinafter refer to Nextel International, Inc., a Delaware
corporation, as successor to Nextel International, Inc., a Washington
corporation.

               Section 1.03. Pursuant to Section 5.02 of the Indenture, NII
Delaware is hereby substituted for, and may exercise every right and power of,
the Company under the Indenture with the same effect as if NII Delaware had been
named as the Company therein, and hereafter the Company, as the predecessor
corporation, shall be relieved of all obligations and covenants under this
Indenture and the Notes.

                                  ARTICLE TWO
                            MISCELLANEOUS PROVISIONS

               Section 2.01. Effect of Supplemental Indenture. Upon the
execution and delivery of this Supplemental Indenture by the Company, NII
Delaware and the Trustee, as of the Effective Time the Indenture shall be
supplemented in accordance herewith and this Supplemental Indenture shall form a
part of the Indenture for all purposes, and every holder of Notes heretofore or
hereafter authenticated and delivered under the Indenture shall be bound
thereby.

               Section 2.02. Indenture Remains in Full Force and Effect. Except
as supplemented hereby, all provisions in the Indenture shall remain in full
force and effect.

               Section 2.03. Confirmation and Preservation of Indenture. The
Indenture as supplemented by this Supplemental Indenture is in all respects
confirmed and preserved.

               Section 2.04. Indenture and Supplemental Indenture Construed
Together. This Supplemental Indenture is an indenture supplemental to and in
implementation of the Indenture, and the Indenture and this Supplemental
Indenture shall henceforth be read and construed together.

               Section 2.05. Conflict with Trust Indenture Act. If any provision
of this Supplemental Indenture limits, qualifies or conflicts with any provision
of the Trust Indenture Act (the "TIA") that is required under the TIA to be part
of and govern any provision of this Supplemental Indenture, the provision of the
TIA shall control. If any provision of this Supplemental Indenture modifies or
excludes any provision of the TIA that may be so modified or excluded, the
provision of the TIA shall be deemed to apply to the Indenture as so modified or
to be excluded by this Supplemental Indenture, as the case may be.

               Section 2.06. Separability Clause. In case any provision in this
Supplemental Indenture shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or impaired thereby.

<PAGE>   4

               Section 2.07. Terms Defined in the Indenture. All capitalized
terms not otherwise defined herein shall have the meanings ascribed to them in
the Indenture.

               Section 2.08. Effect of Headings. The Article and Section
headings herein are for convenience only and shall not affect the construction
hereof.

               Section 2.09. Benefits of Supplemental Indenture, etc. Nothing in
this Supplemental Indenture, the Indenture or the Notes, express or implied,
shall give to any Person, other than the parties hereto and thereto and their
successors hereunder and thereunder and the holders of Notes, any benefit of any
legal or equitable right, remedy or claim under the Indenture, this Supplemental
Indenture or the Notes.

               Section 2.10. Successors and Assigns. All covenants and
agreements in this Supplemental Indenture by the Company shall bind its
successors and assigns, whether so expressed or not.

               Section 2.11. Trustee Not Responsible for Recitals. The recitals
contained herein shall be taken as the statements of the Company and NII
Delaware, and the Trustee assumes no responsibility for their correctness.

               Section 2.12. Certain Duties and Responsibilities of the Trustee.
In entering into this Supplemental Indenture, the Trustee shall be entitled to
the benefit of every provision of the Indenture relating to the conduct or
affecting the liability of or affording protection to the Trustee, whether or
not elsewhere herein so provided.

               Section 2.13. Governing Law. This Supplemental Indenture shall be
governed by and construed in accordance with the laws of the State of New York,
without regard to the conflicts of law principles thereof.

               Section 2.14. Counterparts. This Supplemental Indenture may be
executed in counterparts, each of which, when so executed, shall be deemed to be
an original, but all such counterparts shall together constitute but one and the
same instrument.

<PAGE>   5

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

                                     NEXTEL INTERNATIONAL, INC., a
                                     Washington corporation

                                     By: /s/ ROBERT J. GILKER
                                        ----------------------------------------
                                     Name:  Robert J. Gilker
                                     Title:  Vice President and General Counsel

                                     NEXTEL INTERNATIONAL, INC., a
                                     Delaware corporation

                                     By: /s/ ROBERT J. GILKER
                                        ----------------------------------------
                                     Name:  Robert J. Gilker
                                     Title:  Vice President and General Counsel

                                     THE BANK OF NEW YORK, as Trustee

                                     By: /s/ MARY LAGUMINA
                                        ----------------------------------------
                                     Name:  Mary LaGumina
                                     Title:  Vice President

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00018-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00018-of-00352.parquet"}]]