<PAGE>

                                                                    Exhibit 4.12

SECOND AMENDMENT dated as of December 8, 2000 to the Credit Agreement (as
previously amended, the "Credit Agreement") dated as of December 20, 1999, among
INDEPENDENT WIRELESS ONE CORPORATION, a Delaware corporation (the "Borrower"),
the several lenders from time to time parties thereto (the "Lenders"), CHASE
SECURITIES INC. ("CSI") as Book Manager and Lead Arranger (in such capacities,
the "Book Manager" and "Lead Arranger"), FIRST UNION NATIONAL BANK ("First
Union"), and BNP Paribas ("Paribas") as Senior Managing Agents (First Union and
Paribas, collectively, in such capacities, the "Senior Managing Agents"), UBS
AG, Stamford Branch ("UBS") as Documentation Agent (in such capacity, the
"Documentation Agent") and THE CHASE MANHATTAN BANK, a New York banking
corporation, as Administrative Agent for the Lenders (in such capacity, the
"Administrative Agent").

WHEREAS, the Borrower (such term and each other capitalized term used but not
otherwise defined herein having the meaning assigned to it in the Credit
Agreement) has requested that the Lenders approve amendments to certain
provisions of the Credit Agreement;

WHEREAS, the undersigned Lenders are willing, on the terms and subject to the
conditions set forth herein, to approve such amendments to the Credit Agreement;

NOW, THEREFORE, in consideration of these premises, the Borrower and the
undersigned Lenders hereby agree as follows:

SECTION 1. Amendments. Effective as of the Second Amendment Effective Date (as
defined in Section 3 hereof), the Credit Agreement is hereby amended as follows:

(a) The words "senior subordinated discount notes (the "Senior Subordinated
Notes") in a public offering or in a Rule 144A or other private placement for
aggregate gross

<PAGE>

                                        2

proceeds of at least approximately $100,000,000" are deleted from clause (b) of
the eighth WHEREAS clause of the preamble and the words "Senior Subordinated
Notes" are substituted in lieu thereof.

(b) The phrase "prior to June 30, 2000," is deleted from clause (b)(y) of the
eighth WHEREAS clause of the preamble.

(c) The following definitions are inserted in appropriate alphabetical positions
in Section 1.1:

"Additional Lender": as defined in Section 2.5.

"Incremental Commitment": as defined in Section 2.5.

"Incremental Term Loans": as defined in Section 2.5.

"Interest Reserve Account": an interest reserve account or other similar escrow
arrangement into which the Interest Reserve Account Amount shall be deposited on
the date of issuance of the Senior Interest Reserve Notes and in which the
holders of the Senior Interest Reserve Notes shall be granted a first priority
security interest; provided, however, that the mere establishment of the
Interest Reserve Account shall not be construed to relieve the Borrower or
Holdings, as the case may be, from the obligation to pay the first six
semi-annual interest payments as provided by the terms of the Senior Interest
Reserve Notes.

"Interest Reserve Account Amount": an amount equal to the first six semi-annual
interest payments in respect of the Senior Interest Reserve Notes; provided that
such amount is funded from the proceeds of the issuance of the Senior Interest
Reserve Notes only.

"New Equity Contribution": a contribution of $50,000,000 to the equity of the
Borrower made through Holdings after December 1, 2000 on terms and conditions
satisfactory in all respects to the Administrative Agent.

"New Equity Contribution Condition": the Administrative Agent shall have
received a certificate of the Chief Executive Officer or the Chief Financial
Officer of the Borrower confirming that the Borrower has received $50,000,000 in
proceeds from the New Equity Contribution.

"Offer Period": as defined in Section 2.5.

<PAGE>

                                        3

"Senior Interest Reserve Notes": senior interest reserve notes issued by the
Borrower or Holdings for aggregate cash proceeds (net of the Interest Reserve
Account Amount) of at least $100,000,000, provided that (a) the Interest Reserve
Account shall be established on the date of issuance of such notes, (b) such
notes are not guaranteed by any Special Purpose Subsidiary and (c) any
obligation of the Borrower under such notes and any guarantee of such notes by
the Borrower and its subsidiaries shall be subordinated to all of the
obligations under the Credit Documents on terms and conditions satisfactory in
all respects to the Administrative Agent.

(d) Each of the following definitions in Section 1.1 is amended and restated in
its entirety as follows:

"Additional Financing Event Condition": the Borrower shall have received at
least $100,000,000 either (i) in borrowings from the Subordinated Facility, (ii)
in gross cash proceeds from the issuance of the Senior Subordinated Notes (in
the case of Senior Interest Reserve Notes, net of any requirement to deposit any
proceeds thereof into any interest reserve account or similar escrow
arrangement) or (iii) in gross cash proceeds from the Equity Offering or from a
combination thereof (after giving effect to any prepayments made with the
proceeds thereof); provided that (A) the Subordinated Facility or the Senior
Subordinated Notes, as the case may be (a) shall be subordinated to the
obligations hereunder and under the Guarantees (except in the case of the Senior
Interest Reserve Notes in connection with the Parent Guarantee) on terms and
conditions satisfactory in all respects to the Administrative Agent, (b) shall
mature on a date at least six months subsequent to the Tranche B Maturity Date,
(c) shall not amortize prior to the Tranche B Maturity Date, (d) shall not
require the payment of cash interest until five years from the initial issuance
of the Senior Subordinated Notes or the Subordinated Facility (whichever occurs
first), except in the case of the Senior Interest Reserve Notes (the first six
semi-annual interest payments in respect of which may be paid from the Interest
Reserve Account only and from any source thereafter), (e) shall not contain
covenants, events of default or prepayment events (but excluding call protection
provisions) that are more restrictive than those contained in this

<PAGE>

                                        4

Agreement (other than the covenant in the Subordinated Commitment Letter
relating to investments in Special Purpose Subsidiaries) and (f) shall otherwise
be on market terms and conditions and, except in the case of Senior Interest
Reserve Notes, shall otherwise be issued and subordinated on the terms and
conditions set forth in the Subordinated Commitment Letter and (B) the proceeds
of any Senior Subordinated Notes and/or the Equity Offering issued by Holdings,
and/or the Subordinated Facility borrowed by Holdings, to meet the requirements
of this definition shall be contributed to the Borrower as common equity and/or
loaned to the Borrower on a deeply subordinated basis pursuant to terms and
conditions satisfactory in all respects to the Administrative Agent.

"Commitment": as to any Lender at any time, such Lender's Swing Line Commitment,
Tranche A Term Loan Commitment, Tranche B Term Loan Commitment, Revolving Credit
Commitment and/or Incremental Commitment (if any); collectively, as to all the
Lenders, the "Commitments".

"Senior Subordinated Notes": (a) senior subordinated discount notes issued by
the Borrower or Holdings in a public offering or in a Rule 144A or other private
placement for aggregate gross proceeds of at least $100,000,000 or (b) Senior
Interest Reserve Notes.

"Subordinated Commitment Letter": the commitment letter delivered to the
Administrative Agent pursuant to Section 6.1(q) on December 20, 1999, as amended
by amendments to such commitment letter dated June 30, 2000 and December 8,
2000.

"Subordinated Debt": the Senior Subordinated Notes or the Subordinated Facility
and refinancings thereof permitted hereunder;

provided that the Subordinated Facility, the Senior Subordinated Notes and any
refinancings thereof, as the case may be (a) shall be subordinated to the
obligations hereunder and under the Guarantees (except in the case of the Senior
Interest Reserve Notes in connection with the Parent Guarantee) on terms and
conditions satisfactory in all respects to the Administrative Agent, (b) shall
mature on a date at least six months subsequent to the Tranche B Maturity Date,
(c) shall not amortize prior

<PAGE>

                                        5

to the Tranche B Maturity Date, (d) shall not require the payment of cash
interest until five years from the initial issuance of the Senior Subordinated
Notes or the Subordinated Facility which ever occurs first, except in the case
of the Senior Interest Reserve Notes (the first six semi-annual interest
payments in respect of which may be paid from the Interest Reserve Account only
and from any source thereafter), (e) shall not contain covenants, events of
default or prepayment events (but excluding any call protection provisions) that
are more restrictive than those contained in this Agreement (other than the
covenant in the Subordinated Commitment Letter relating to investments in
Special Purpose Subsidiaries) and (f) shall otherwise be on market terms and
conditions and, except in the case of Senior Interest Reserve Notes, shall
otherwise be issued and subordinated on the terms and conditions set forth in
the Subordinated Commitment Letter.

"Tranche A Commitment Period": the period from and including the later of (x)
the Effective Date and (y) the date the Additional Financing Event Condition is
satisfied to but excluding the earlier of the second anniversary of the
Effective Date and the date of termination of the Tranche A Term Loan
Commitments as provided herein. Notwithstanding the foregoing, (A) an aggregate
of $30,000,000 of the Tranche A Term Loan Commitments shall be available during
the period from and including June 30, 2000 to but excluding the earlier of (x)
the second anniversary of the Effective Date and (y) the date of the termination
of Tranche A Commitments as provided herein and (B) an additional $30,000,000 of
the Tranche A Term Loan Commitments shall be available during the period from
and including the date on which the New Equity Contribution Condition is
satisfied to but excluding the earlier of (x) the second anniversary of the
Effective Date and (y) the date of the termination of Tranche A Commitments as
provided herein

(e) A new Section 2.5 is inserted immediately following Section 2.4 and shall
read as follows:

Section 2.5. Incremental Term Loans. On or prior to the last day of the Tranche
A Commitment Period, the Borrower may, by notice to the Administrative Agent
(which shall promptly deliver a copy to each of the

<PAGE>

                                        6

Lenders), request the addition of a new tranche of term loans (the "Incremental
Term Loans"); provided, however, that both (x) at the time of any such request
and (y) after giving effect to any such Incremental Term Loans, no Default shall
exist and the Borrower shall be in compliance with each financial covenant
(calculated, in the case of clause (y), on a pro forma basis to give effect to
any borrowing of Incremental Term Loans). The Incremental Term Loans shall (i)
be in an aggregate principal amount not in excess of $25,000,000, (ii) rank pari
passu in right of payment and of security with the other Loans, (iii) have an
average weighted life equal to or longer than the Tranche A Term Loans, (iv) be
drawn on or prior to the last day of the Tranche A Commitment Period; provided
that, notwithstanding anything to the contrary set forth herein, no Incremental
Term Loans shall be drawn until the Additional Financing Event Condition shall
have been satisfied, (v) have such pricing as may be agreed by the Borrower and
the Persons providing such Incremental Term Loans and (vi) otherwise be treated
hereunder no more favorably than the Tranche A Term Loans. Such notice shall set
forth the requested amount of Incremental Term Loans, and shall offer each
Lender the opportunity to offer a commitment (the "Incremental Commitment") to
provide Incremental Term Loans by giving written notice of such offered
commitment to the Administrative Agent and the Borrower within a time period
(the "Offer Period") to be specified in the Borrower's notice; provided,
however, that no existing Lender will be obligated to subscribe for any portion
of such commitments. In the event that, at the expiration of the Offer Period,
Lenders shall have provided commitments in an aggregate amount less than the
total amount of the Incremental Term Loans requested by the Borrower, the
Borrower shall have the right to arrange for one or more banks or other
financial institutions (any such bank or other financial institution being
called an "Additional Lender") to extend commitments to provide Incremental Term
Loans in an aggregate amount equal to the unsubscribed amount; provided that
each Additional Lender shall be subject to the approval of the Administrative
Agent (which approval shall not be unreasonably withheld); and provided further
that the Additional Lenders shall be offered the opportunity to provide the
Incremental Term Loans only on terms previously offered to the existing Lenders
pursuant to

<PAGE>

                                        7

the immediately preceding sentence. Commitments in respect of Incremental Term
Loans shall become Commitments under this Agreement pursuant to an Incremental
Facility Amendment executed by each of the Borrower, Holdings, each Subsidiary
that is party to a Subsidiary Guarantee, if any, each Lender agreeing to provide
such Commitment, if any, each Additional Lender, if any, and the Administrative
Agent. The effectiveness of any Incremental Facility Amendment shall be subject
to (A) the satisfaction on the date thereof and, if different, on the date on
which the Incremental Term Loans are made, of each of the conditions set forth
in Section 6.3 and (B) the receipt by the Administrative Agent of opinions of
counsel to the Borrower, addressed to the Lenders and the Administrative Agent
and dated the date of the Incremental Facility Amendment, from counsel, and in
form and substance, satisfactory to the Administrative Agent.

(f) A new clause (v) is inserted immediately after the word "excluding," and
immediately before clause (w) in the parenthetical phrase in Section 4.4(b)(i)
and shall read as follows: "(v) the New Equity Contribution,".

(g) Clause (x) of the proviso to clause (B) of Section 8.1(i) is amended and
restated in its entirety to read as follows: "(x) $190,000,000 in the case of
Senior Interest Reserve Notes and $150,000,000 in all other cases".

(h) The proviso immediately following clause (C) of Section 8.1(i) is amended
and restated in its entirety to read as follows:

"; provided further that (i) all such Subordinated Debt and any such
refinancings shall be issued on market terms and conditions, (ii) no part of the
principal amount of any such Indebtedness shall have a maturity date earlier
than the six month anniversary of the final Tranche B Installment Payment Date,
(iii) such Indebtedness shall not require the payment of cash interest until
five years from the initial issuance of the Senior Subordinated Notes or the
Subordinated Facility whichever occurs first, except in the case of the Senior
Interest Reserve Notes (the first six semi-annual interest payments in respect
of which may be paid from the Interest Reserve Account only

<PAGE>

                                        8

and from any source thereafter), (iv) the representations, warranties, covenants
(other than the covenant in the Subordinated Commitment Letter relating to
investments in Special Purpose Subsidiaries) and events of default (but
excluding any call protection provisions) relating thereto shall be no more
restrictive than those under this Agreement as of the date hereof and any
financial covenants shall be incurrence rather than maintenance covenants, and
(v) any such Indebtedness shall be subordinated to the obligations of the Credit
Parties under the Credit Documents on substantially the same terms as the Senior
Subordinated Notes or the Subordinated Facility or otherwise on customary terms
and conditions approved by the Administrative Agent (such approval not to be
unreasonably withheld or delayed) or, except in the case of the Senior Interest
Reserve Notes, shall otherwise be issued and subordinated on the terms and
conditions set forth in the Subordinated Commitment Letter"

(i) A new subsection (n) is inserted at the end of Section 8.2 and shall read as
follows:

(n) Liens on the Interest Reserve Account in favor of the holders of the Senior
Interest Reserve Notes.

(j) Section 8.9 (h) is amended and restated in its entirety to read as follows:

(h) Interest Coverage Ratio. (A) In the event that the Additional Financing
Event Condition is satisfied other than by the issuance of Senior Interest
Reserve Notes, permit the Interest Coverage Ratio for any period of four
consecutive fiscal quarters beginning and ending prior to on the last day of any
fiscal quarter on any date or during any period set forth below to be less than
the ratio set forth opposite such date or period.

                  Date or Period             Ratio
                  ---------------            ---------
                  03/31/04                   1.00 to 1
                  06/30/04                   1.25 to 1
                  09/30/04                   1.50 to 1

<PAGE>

                                        9

        Date or Period             Ratio
        ---------------            ---------
        12/31/04                   2.00 to 1
        03/31/05                   2.25 to 1
        06/30/05                   2.50 to 1
        09/30/05                   2.00 to 1
        09/30/06 and thereafter    2.25 to 1



(B) In the event that the Additional Financing Event Condition is satisfied by
the issuance of Senior Interest Reserve Notes, permit the Interest Coverage
Ratio for any period of four consecutive fiscal quarters beginning and ending
prior to on the last day of any fiscal quarter on any date or during any period
set forth below to be less than the ratio set forth opposite such date or
period.

                    Date or Period             Ratio
                    ---------------            ---------
                    09/30/04                   1.00 to 1
                    12/31/04                   1.25 to 1
                    06/30/05                   1.50 to 1
                    12/31/05                   2.00 to 1
                    09/30/06                   2.25 to 1
                    03/31/07 and thereafter    2.50 to 1

(k) Section 8.9 (i) is amended and restated in its entirety to read as follows:

<PAGE>

                                       10

(i) Fixed Charges Ratio. (A) In the event that the Additional Financing Event
Condition is satisfied other than by the issuance of Senior Interest Reserve
Notes, permit the ratio of Consolidated EBITDA to Fixed Charges for any period
of four consecutive fiscal quarters ending on the last day of any fiscal quarter
on any date or during any period set forth below to Fixed Charges for such
period or four consecutive fiscal quarters to be less than the ratio set forth
opposite such date or period.

                                Date or Period    Ratio
                                ----------------  -----
                                9/30/04-12/31/07  1.1 to 1
                                         3/31/08  1.2 to 1
                                and thereafter

(B) In the event that the Additional Financing Event Condition is satisfied by
the issuance of Senior Interest Reserve Notes, permit the ratio of Consolidated
EBITDA to Fixed Charges for any period of four consecutive fiscal quarters
ending on the last day of any fiscal quarter on any date or during any period
set forth below to Fixed Charges for such period or four consecutive fiscal
quarters to be less than the ratio set forth opposite such date or period.

                                Date or Period      Ratio
                                --------------      -----
                                6/30/05 - 12/31/06  1.1 to 1
                                3/31/07
                                and thereafter      1.2 to 1

(l) Clause (b) of Section 8.16 is amended and restated to read in its entirety
as follows:

"(b) make any cash interest payments with respect to and any Indebtedness
outstanding pursuant to subsection 8.1(i) (except with respect to the Senior
Interest Reserve Notes and refinancings thereof) prior to five years from the
initial issuance of the Subordinated Facility or the Senior Subordinated Notes,
which ever occurs first (other than as permitted by clause (a) above) or"

<PAGE>

                                       11

(m) Section 9(l) is hereby amended by deleting the reference therein to
"December 30, 2000" and inserting in lieu thereof a reference to "March 31,
2001".

SECTION 2. Representations and Warranties. The Borrower represents and warrants
to each of the Lenders that, after giving effect to the amendments contemplated
hereby, (a) the representations and warranties of the Borrower set forth in the
Credit Agreement are true and correct in all material respects on and as of the
date of this Amendment, except to the extent such representations and warranties
expressly relate to an earlier date (in which case such representations and
warranties shall be true and correct in all material respects as of the earlier
date) and (b) no Default has occurred and is continuing.

SECTION 3. Effectiveness. This Amendment shall become effective as of the date
(the "Second Amendment Effective Date") when the following conditions shall have
been satisfied:

(a) The Administrative Agent (or its counsel) shall have received copies hereof
that, when taken together, bear the signatures of the Borrower and the Required
Lenders.

(b) The Administrative Agent shall have received a certificate of the Chief
Executive Officer or the Chief Financial Officer of the Borrower confirming
compliance as of the Second Amendment Effective Date with the conditions set
forth in clauses (a), (b) and (c) of Section 6.3 of the Credit Agreement.

(c) The Administrative Agent and the Lenders shall have received all fees,
expenses and other consideration presented for payment on or before the date
hereof.

SECTION 4. Amendment Fee. The Borrower agrees to pay to the undersigned Lenders
such amendment fees, and at such times, as have been separately agreed upon.

SECTION 5. Applicable Law. THIS AMENDMENT SHALL BE CONSTRUED IN ACCORDANCE WITH
AND GOVERNED BY THE LAW OF THE STATE OF NEW YORK.

SECTION 6. No Other Amendments. Except as expressly set forth herein, this
Amendment shall not by

<PAGE>

                                       12

implication or otherwise limit, impair, constitute a waiver of, or otherwise
affect the rights and remedies of any party under, the Credit Agreement, nor
alter, modify, amend or in any way affect any of the terms, conditions,
obligations, covenants or agreements contained in the Credit Agreement, all of
which are ratified and affirmed in all respects and shall continue in full force
and effect. This Amendment shall apply and be effective only with respect to the
provisions of the Credit Agreement specifically referred to herein.

SECTION 7. Counterparts. This Amendment may be executed in two or more
counterparts, each of which shall constitute an original, but all of which when
taken together shall constitute but one contract. Delivery of an executed
counterpart of a signature page of this Amendment by facsimile transmission
shall be as effective as delivery of a manually executed counterpart of this
Amendment.

SECTION 8. Headings. Section headings used herein are for convenience of
reference only, are not part of this Amendment and are not to affect the
construction of, or to be taken into consideration in interpreting, this
Amendment.

<PAGE>

                                       13

IN WITNESS WHEREOF, the Borrower and the undersigned Lenders have caused this
Amendment to be duly executed by their duly authorized officers, all as of the
date first above written.

                      INDEPENDENT WIRELESS ONE CORPORATION,

                                       by:

                             /s/ David L. Standing
                             --------------------------
                             Name: David L. Standing
                             Title: Chief Operating Officer


THE CHASE MANHATTAN BANK, as Lender and Administrative Agent,

by:

                             /s/ Constance M. Coleman
                             --------------------------
                             Name: Constance M. Coleman
                             Title: Vice President



                            UBS AG, STAMFORD BRANCH,

                                       by:

                             /s/ Robert Parsons
                             --------------------------
                             Name: Robert Parsons
                             Title: Managing Director
                                    Leveraged Finance

by:

                             /s/ Daniel W. Ladd III
                             --------------------------
                             Name: Daniel W. Ladd III
                             Title: Executive Director


                             FIRST UNION NATIONAL BANK,

<PAGE>

                                       by:

                             /s/ Keith Northern
                             --------------------------
                             Name: Keith Northern
                             Title: Director / SVP

<PAGE>

                                       14

                                  BNP PARIBAS,

                                       by:


                             /s/ Lynne S. Randall
                             --------------------------
                             Name: Lynne S. Randall
                             Title: Managing Director



by:



                             /s/ Sean Faherty
                             --------------------------
                             Name: Sean Faherty
                             Title: Vice President



                           DLJ CAPITAL FUNDING, INC.,

                                       by:


                             /s/ David L. Miller
                             --------------------------
                             Name: David L. Miller
                             Title: Sen. Vice President



                      WESTDEUTSCHE LANDESBANK GIROZENTRALE,

                                       by:


                             /s/ Michael D. Peist
                             --------------------------
                             Name: Michael D. Peist
                             Title: Associate Director



by:



                             /s/ Peter Stevenson
                             --------------------------
                             Name: Peter Stevenson
                             Title: Associate Director

<PAGE>

                     BANK OF TOKYO-MITSUBISHI TRUST COMPANY,

                                       by:

                                 /s/ S. Akita
                                 --------------------------
                                 Name: S. Akita
                                 Title: Vice President

<PAGE>

                                       15

                            THE BANK OF NOVA SCOTIA,

                                       by:

                            /s/ Vincent J. Fitzgerald
                            --------------------------
                            Name: Vincent J. Fitzgerld
                            Title:Authorized Signatory

                       THE CIT GROUP/EQUIPMENT FINANCING,

                                       by:

                            /s/ John P. Sirico, II
                            --------------------------
                            Name: John P. Sirico, II
                            Title: Vice President

                             IBM CREDIT CORPORATION,

                                       by:

                            /s/ Thomas S. Curcio
                            --------------------------
                            Name: Thomas S. Curcio
                            Title: Manager of Credit,
                                   Commercial and
                                   Specialty Financing

                              FORTIS CAPITAL CORP.,

                                       by:

                            /s/ Alan E. McLintock
                            --------------------------
                            Name: Alan E. McLintock
                            Title: Managing Director

                                 KZH ING-1 LLC,

                                       by:

<PAGE>

                         /s/ Kimberly Rowe
                         --------------------------
                         Name: Kimberly Rowe
                         Title: Authorized Agent

<PAGE>

                                       16

                                 KZH ING-2 LLC,

                                       by:

                                 /s/ Kimberly Rowe
                                 --------------------------
                                 Name: Kimberly Rowe
                                 Title: Authorized Agent

                                 KZH ING-3 LLC,

                                       by:

                                 /s/ Kimberly Rowe
                                 --------------------------
                                 Name: Kimberly Rowe
                                 Title: Authorized Agent

               ING CAPITAL SENIOR SECURED HIGH INCOME FUND, L.P.,

                          by ING CAPITAL ADVISORS LLC,
                             as investment advisor,

                                       by:

                                 /s/ Jonathan David
                                 ----------------------
                                 Name: Jonathan David
                                 Title: Vice President