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                                                                    EXHIBIT 10.6

                                FOURTH AMENDMENT


                FOURTH AMENDMENT (this "Amendment"), dated as of January 15,
1998, among PAGEMART WIRELESS, INC. (formerly PageMart Nationwide, Inc.) (the
"Borrower"), the financial institutions party to the Credit Agreement referred
to below (the "Lenders"), BT COMMERCIAL CORPORATION, as Agent (the "Agent"),
and BANKERS TRUST COMPANY, as Issuing Bank (the "Issuing Bank").  All
capitalized terms used herein and not otherwise defined herein shall have the
respective meanings provided such terms in the Credit Agreement.


                             W I T N E S S E T H :

                 WHEREAS, the Borrower, the Lenders, the Agent, and the Issuing
Bank are parties to a Credit Agreement, dated as of May 11, 1995 (as amended,
modified or supplemented through, but not including, the date hereof, the
"Credit Agreement");

                 WHEREAS, the parties hereto wish to further modify the Credit
Agreement as herein provided; and

                 WHEREAS, subject to the terms and conditions of this
Amendment, the parties hereto agree as follows;


                 NOW, THEREFORE, it is agreed:

                 1.       Section 1 of the Credit Agreement is hereby amended
                          by:

                 (a)      inserting the following definitions in the
appropriate alphabetical order:

                 "'Capital Expenditure Amount' shall mean (i) $175,000,000 less
         (ii) the amount by which (x) $90,000,000 exceeds (y) the Net
         Refinancing Amount plus (iii) the Permitted Equity Basket.

                 'Consent Solicitation Statement'  shall mean the Amended
         Consent Solicitation Statement dated December 17, 1997 relating to the
         15% Senior Discount Notes due 2005, a copy of which has been provided
         to the Agent and the Lenders prior to the Fourth Amendment Effective
         Date.
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                 'Fourth Amendment Effective Date' shall mean the date on which
         the Fourth Amendment to this Agreement becomes effective in accordance
         with its terms.

                 'Indenture Amendments' shall mean, collectively, (i) the
         amendments to the Indenture for the 12 1/4% Senior Discount Notes due
         2003 described in the Offer to Purchase and (ii) the amendments to the
         Indenture for the 15% Senior Discount Notes due 2005 described in the
         Consent Solicitation Statement.

                 'Merger' shall mean the merger of PageMart into the Borrower
         pursuant to which the Borrower will be the surviving corporation.

                 'Net Refinancing Amount' shall mean (i) the net cash proceeds
         received by the Borrower from the issuance of the Senior Subordinated
         Notes, less (ii) the amounts paid in connection with the prepayment of
         the 12 1/4% Senior Discount Notes due 2003 less (iii) all fees and
         expenses incurred in connection with the Refinancing (including,
         without limitation, all consent fees payable in connection with the
         Consent Solicitation Statement).

                 'Offer to Purchase' shall mean the Offer to Purchase and
         Consent Solicitation Statement relating to the 12 1/4% Senior Discount
         Notes due 2003 dated December 23, 1997, a copy of which has been
         provided to the Agent and the Lenders prior to the Fourth Amendment
         Effective Date.

                 'Refinancing' shall mean (i) the repurchase of the 12 1/4%
         Senior Discount Notes due 2003 as described in the Offer to Purchase,
         (ii) the Indenture Amendments, (iii) the Merger and (iv) the issuance
         of the Senior Subordinated Notes.

                 'Senior Subordinated Notes' shall mean the senior subordinated
         discount notes to be issued by the Borrower, the terms of which are
         described in the Offering Memorandum issued January 6, 1998 (a copy of
         which has been provided to the Agent and the Lenders prior to the
         Fourth Amendment Effective Date) and which on the date of issuance
         thereof are otherwise satisfactory in form and substance to the
         Agent.";

                 (b)      amending the definition of "Eligible Accounts
Receivable" set forth therein by (x) deleting the "(i)" immediately after the
word "Accounts" in the first line thereof and (y) deleting the phrase "and (ii)
title to which has been effectively conveyed by PageMart to the Borrower
pursuant to the Asset Transfer Documents";

                 (c)      amending the definition of "Indentures" set forth
therein by (i) deleting the "and" before clause (ii) thereof and inserting a
comma in lieu thereof and (ii) adding the following at the end thereof "and
(iii) the Indenture pursuant to which the





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Borrower issues its Senior Subordinated Notes, as each such Indenture may be
amended and modified from time to time in accordance with the terms hereof";

                 (d)      amending the definition of "PageMart" set forth
therein by adding the following phrase at the end thereof "provided that after
the consummation of the Merger all references to 'PageMart' set forth in the
Credit Documents shall be deemed to be references to the Borrower";

                 (e)      amending the definition of "Permitted Equity Basket"
set forth therein by (i) inserting the phrase "received after the Fourth
Amendment Effective Date" after the word "proceeds" in the second line thereof
and (iii) inserting the phrase "after the Fourth Amendment Effective Date and"
after the word "used" in the fourth line thereof; and

                 (f)      deleting the definitions of "Asset Transfers," "Asset
Transfer Documents," "Permitted Indenture Financing," "Permitted Indenture
Financing Basket" and "Permitted Two Way Vendor Financing" set forth therein
(and all references to such terms in the Credit Agreement are also deleted).

                 2.       Section 2.12 of the Credit Agreement is hereby
amended by deleting the phrase "(a) the segregation of Collections in respect
of Accounts, on the one hand, from collections in respect of accounts
receivable of PageMart, on the other hand and (b)".

                 3.       Section 7.2 of the Credit Agreement is hereby amended
by adding the following phrase at the end of the parenthetical in the second
line thereof "and any other week if no Revolving Loan or Letter of Credit is
then outstanding".

                 4.       Section 8.6 of the Credit Agreement is hereby deleted
in its entirety and the following provision is inserted in lieu thereof:

                 "8.6     Capital Expenditures.  Neither the Borrower nor any
         of its Restricted Subsidiaries shall make, or commit to make, any
         Capital Expenditures after the Fourth Amendment Effective Date other
         than (a) Capital Expenditures made or committed to be made the
         aggregate amount of which does not exceed the Capital Expenditure
         Amount and (b) Capital Expenditures allowed under Section 8.7(d)."

                 5.       Section 8.7 of the Credit Agreement is hereby amended
by (i) deleting the text of clauses (a) and (e) of said Section 8.7 in their
entirety and inserting "[Intentionally Deleted]" in lieu thereof and (ii)
deleting from clauses 5(c) and (d) of said Section 8.7 the following phrase
"the Permitted Indenture Financing Basket".

                 6.       Section 8.8 of the Credit Agreement is hereby amended
                          as follows:

                             (i)  clause (d) of said Section 8.8 is amended by
                 deleting the phrase "Indebtedness under the Indentures and any
                 other" set forth therein;





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                            (ii)  clause (g) of said Section 8.8 is amended by
                 adding the following phrase at the end thereof "except that
                 the Borrower may guarantee Indebtedness of PageMart Canada
                 Holding Corporation provided that the aggregate principal
                 amount of such guaranteed Indebtedness does not exceed
                 $5,000,000";

                           (iii)  clause (h) of said Section 8.8 is hereby
                 deleted in its entirety and substituted in lieu thereof is the
                 following:

                                  "(h)     Indebtedness of the Borrower, and
                          prior to the Merger, PageMart under the Indentures,
                          provided that (x) the initial accreted value of the
                          Senior Subordinated Notes shall not exceed $225
                          million or such higher amount as shall be permitted
                          under the Indentures, (y) the Senior Subordinated
                          Notes may be issued only in connection with the
                          Refinancing and (z) the aggregate principal amount of
                          the 12 1/4% Senior Discount Notes due 2003 which
                          remain outstanding after the consummation of the
                          Refinancing shall not exceed, $58,000,000;", and

                            (iv)  deleting the text of clause (j) of said
                 Section 8.8 in its entirety and inserting "[Intentionally
                 Deleted]" in lieu thereof.

                 7.       Section 8.12(b) of the Credit Agreement is hereby
amended by (i) deleting the "and" before clause (iv) thereof and inserting a
comma in lieu thereof and (ii) inserting the following at the end thereof "and
(v) the Borrower may make prepayments of the 12 1/4% Senior Discount Notes due
2003 as described in the Offer to Purchase provided that (x) such prepayments
do not exceed the aggregate net proceeds received by the Borrower from the
issuance of the Senior Subordinated Notes, (y) the amounts paid in respect of
such prepayments do not exceed the amount set forth in the Offer to Purchase
and (z) such prepayments may only be made in connection with the Refinancing."

                 8.  Article 8 of the Credit Agreement is hereby amended by
adding the following new covenant:

                 "8.19  Indentures.  (a) The Borrower shall not, and shall not
         permit any of its Subsidiaries to, amend or modify any Indenture
         without the prior written consent of the Agent and the Majority
         Lenders except that the Indenture Amendments shall be permitted.

                 (b)      The Borrower shall not designate any Indebtedness as
         'Designated Senior Indebtedness' under the Indenture for the Senior
         Subordinated Notes."





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                 9.  Section 9.1(h) of the Credit Agreement is hereby amended
deleting the word "either" set forth in the second line thereof and inserting
the word "any" in lieu thereof.

                 10.  This Amendment shall become effective on the date (the
"Fourth Amendment Effective Date") when each of the following conditions have
been met:

                 (a)      the Borrower, the Agent, the Majority Lenders and the
         Issuing Bank shall have signed a counterpart hereof (whether the same
         or different counterparts) and shall have delivered (including by way
         of facsimile transmission) the same to the Agent at the Notice Office;

                 (b)      the Agent shall have received resolutions of the
         Board of Directors of the Borrower, which resolutions shall be
         certified by the Secretary or any Assistant Secretary of the Borrower
         and shall authorize the execution, delivery and performance by the
         Borrower of this Amendment and the consummation of the transactions
         contemplated hereby, and the foregoing shall be reasonably acceptable
         to the Agent;

                 (c)      the Merger and the Indenture Amendments shall have
         become effective;

                 (d)      the Agent shall have received evidence satisfactory
         to it that all filings, notices and recordings necessary and advisable
         to perfect the security interests created under the Collateral
         Documents after giving effect to the Merger had been made, given or
         accomplished.

                 11.  In order to induce the Banks to enter into this
Amendment, the Borrower hereby represents and warrants that:

                 (a)   no Default or Event of Default exists on the Fourth
         Amendment Effective Date, after giving effect to this Amendment and
         the Refinancing; and

                 (b)   on the Fourth Amendment Effective Date, and after giving
         effect to this Amendment and the Refinancing, all representations and
         warranties contained in the Credit Agreement and in the other Credit
         Documents are true and correct in all material respects as though such
         representations and warranties were made on the Fourth Amendment
         Effective Date.

                 12.  This Amendment may be executed in any number of
counterparts and by the different parties hereto on separate counterparts, each
of which counterparts when executed and delivered shall be an original, but all
of which shall together constitute one and the same instrument.  A complete set
of counterparts shall be delivered to the Borrower and the Agent.





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                 13.  THIS AMENDMENT AND THE RIGHTS AND OBLIGATIONS OF THE
PARTIES HEREUNDER SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAW
OF THE STATE OF NEW YORK.

                 14.  From and after the Fourth Amendment Effective Date, all
references in the Credit Agreement and each of the other Credit Documents to
the "Credit Agreement" shall be deemed to be references to the Credit Agreement
as modified hereby.

                 15.  This Amendment is limited as specified and shall not
constitute a modification, acceptance or waiver of any other provision of the
Credit Agreement or any other Credit Document.


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                 IN WITNESS WHEREOF, each of the parties hereto has caused a
counterpart of this Amendment to be duly executed and delivered as of the date
first above written.



                                           PAGEMART WIRELESS, INC.


                                           By                          
                                              ----------------------------------
                                           ---

                                           Title:



                                           BT COMMERCIAL CORPORATION,
                                           as Agent


                                           By                          
                                              ----------------------------------
                                           ---

                                           Title:



                                           BANKERS TRUST COMPANY,
                                           as Issuing Bank


                                           By                          
                                              ----------------------------------
                                           ---

                                           Title:



                                           FIRST UNION NATIONAL BANK


                                           By                          
                                              ----------------------------------
                                           ---

                                           Title:





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                                           BANK ONE, TEXAS, N.A.


                                           By                          
                                              ----------------------------------
                                           ---

                                           Title:



                                           TORONTO DOMINION (TEXAS), INC)


                                           By                          
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                                           ---

                                           Title:



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