|SUPPLEMENTAL INDENTURE


SUPPLEMENTAL
INDENTURE (this Supplemental Indenture) executed as of March 6, 2003, by
and among Arch Wireless Holdings, Inc., a Delaware corporation (the Company),
Arch Wireless Communications, Inc., a Delaware corporation (Arch), Arch
Wireless, Inc., a Delaware corporation (the Parent), and the direct and
indirect subsidiaries of the Parent listed on Schedule Ihereto (such subsidiaries,
the Subsidiary Guarantors, and together with Arch and the Parent, herein the
Guarantors) and The Bank of New York, a New York banking corporation, as
Trustee (the Trustee).


RECITALS


WHEREAS,
the Company, the Guarantors and the Trustee have heretofore executed and delivered that
certain Indenture, dated as of May 29, 2002, as amended by the Supplemental Indenture
dated as of August 14, 2002 and made effective as of May 29, 2002 (the
Indenture), with respect to the Companys 10% Senior Subordinated Secured
Notes Due 2007 (the Notes);


WHEREAS,
Section 8.02 of the Indenture provides that the Company and the Guarantors, when
authorized by a Board Resolution, and the Trustee, together with the written consent of
the Majority Noteholders, may, under certain circumstances, enter into an indenture or
indentures supplemental to the Indenture for the purpose of adding any provisions to or
changing in any manner or eliminating or waiving (subject to Section 4.03 of the
Indenture) any of the provisions of the Indenture or of modifying in any manner the rights
of the Holders under the Indenture;


WHEREAS,
the Company desires to amend certain sections of the Indenture to revise or supplement the
text of certain terms of the Indenture, and in connection therewith, the Company has been
soliciting written consents of the Holders to the amendments to the Indenture set forth
herein (and to the execution of this Supplemental Indenture), and the Company has now
obtained such written consents from the Holders of a majority in the aggregate principal
amount of the outstanding Notes; accordingly, this Supplemental Indenture and the
amendments set forth herein are authorized pursuant to Section 8.02 of the Indenture; and


WHEREAS,
the execution and delivery of this Supplemental Indenture has been duly authorized by the
parties hereto, and all other acts necessary to make this Supplemental Indenture a valid
and binding supplement to the Indenture, effectively amending and supplementing the
Indenture as set forth herein, have been duly taken;


NOW,
THEREFORE, in consideration of the above premises and for other good and valuable
consideration, the receipt of which is hereby acknowledged, it is mutually agreed, for the
equal and proportionate benefit of all Holders, as follows:



ARTICLE ONE


Upon
execution of this Supplemental Indenture by the Company and the parties hereto, then
automatically (without further act by any person) with respect to all outstanding Notes,
the Indenture is hereby amended in the following respects:


1.1     
      Section 9.02 (b) shall be deleted in its entirety, and the following is substituted in lieu thereof:


     (b)   
          In the event and on each occasion that any Net Cash Proceeds are received by or
          on behalf of the Company, on the earlier of the next succeeding Interest Payment
          Date or Redemption Date, the Company shall redeem Notes in an amount equal to
          the aggregate amount of such Net Cash Proceeds plus any interest accrued and
          paid thereon (subject to the requirements of Section 9.05). Within five Business
          Days after receipt of the Net Cash Proceeds, the Company shall pay to the
          Collateral Agent such Net Cash Proceeds, to be held by the Collateral Agent in
          the Collateral Account established pursuant to Section 5.2(a) of the Collateral
          Agent Agreement for the benefit of the Holders of the Notes. The Company shall
          direct the Collateral Agent to invest the amount so deposited in an interest
          bearing money market investment selected by the Company. On the earlier of the next
          succeeding Interest Payment Date or Redemption Date, the Trustee shall direct
          the Collateral Agent to deliver such Net Cash Proceeds, together with any
          interest accrued and paid thereon, to the Trustee for payment to the Holders of
          the Notes.


1.2
     Section 9.02 (d) shall be deleted in its entirety, and the following is substituted in lieu thereof:


     (d)   
          In connection with any mandatory redemption pursuant to this Section 9.02, on
          the Determination Date, or 10 days prior to an Redemption Date if Net Cash
          Proceeds are to be delivered to the Trustee on such Redemption Date, the Company
          shall deliver to the Trustee a notice stating which portion of the funds to be
          delivered to the Trustee on the earlier of the next Interest Payment Date or
          Redemption Date will constitute ordinary interest payments, which portion will
          constitute redemptions made with Net Cash Proceeds pursuant to clause (b) above,
          and which portion will constitute redemptions made with Excess Cash Flow
          pursuant to clause (c) above.





1.3   Section 10.21
of the Indenture shall be deleted in its entirety, and the following is substituted in lieu thereof:


"SECTION 10.21  
       Minimum EBITDA.


The
Note Parties shall have, as of the last day of each quarter set forth below, EBITDA for
such quarter of not less than the following:
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | Quarter Ending     | Minimum Quarterly EBITDA
(dollars in millions) | 
| | ------------------ | ---------------------------------------------- | 
| | June 30, 2002      | 46.5                                           | 
| | September 30, 2002 | 45.5                                           | 
| | December 31, 2002  | 42.9                                           | 
| | March 31, 2003     | 41.0                                           | 
| | June 30, 2003      | 36.5                                           | 
| | September 30, 2003 | 34.3                                           | 
| | December 31, 2003  | 30.9                                           | 
| | March 31, 2004     | 26.9                                           | 
| | June 30, 2004      | 34.4                                           | 
| | September 30, 2004 | 33.9                                           | 
| | December 31, 2004  | 34.0                                           | 
| | March 31, 2005     | 33.0                                           | 
| | June 30, 2005      | 33.9                                           | 
| | September 30, 2005 | 34.2                                           | 
| | December 31, 2005  | 34.7                                           | 
| | March 31, 2006     | 33.1                                           | 
| | June 30, 2006      | 34.6                                           | 
| | September 30, 2006 | 36.1                                           | 
| | December 31, 2006  | 37.4                                           | 
| | March 31, 2007     | 36.6                                           | 

|1.4   Section 10.22 of
the Indenture shall be deleted in its entirety, and the following is substituted in lieu thereof:


SECTION 10.22         
Minimum Direct Units in Service.


The
Note Parties will maintain a number of Direct Units in Service as of the last day of the
quarter, not less than as set forth opposite such day:
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | Quarter Ending     | Minimum Direct Units in Service
(units in thousands) | 
| | ------------------ | ---------------------------------------------------- | 
| | June 30, 2002      | 4,215.2                                              | 
| | September 30, 2002 | 4,002.7                                              | 
| | December 31, 2002  | 3,819.3                                              | 
| | March 31, 2003     | 3,630.1                                              | 
| | June 30, 2003      | 3,558.1                                              | 
| | September 30, 2003 | 3,301.6                                              | 
| | December 31, 2003  | 3,055.4                                              | 
| | March 31, 2004     | 2,909.4                                              | 
| | June 30, 2004      | 3,129.5                                              | 
| | September 30, 2004 | 3,042.3                                              | 
| | December 31, 2004  | 2,957.5                                              | 
| | March 31, 2005     | 2,896.9                                              | 
| | June 30, 2005      | 2,837.6                                              | 
| | September 30, 2005 | 2,779.5                                              | 
| | December 31, 2005  | 2,722.6                                              | 
| | March 31, 2006     | 2,600.3                                              | 
| | June 30, 2006      | 2,566.4                                              | 
| | September 30, 2006 | 2,532.8                                              | 
| | December 31, 2006  | 2,499.7                                              | 

|1.5   Section 10.23 of
the Indenture shall be deleted in its entirety, and the following is substituted in lieu thereof:


SECTION 10.23         
Minimum Consolidated SRM Revenues..


The
Note Parties shall maintain, as of the last day of each quarter set forth below,
consolidated SRM revenue for such quarter of not less than the Minimum Quarterly
Consolidated SRM Revenue listed below:
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|Quarter Ending     | Minimum Quarterly
         Consolidated SRM Revenue
         (dollars in millions) | Planned One Way
         SRM Revenue
         (dollars in millions) | Planned Two Way 
         SRM Revenue
         (dollars in millions)
|------------------ | ---------------------------------------------------------------------------------- | ------------------------------------------------------------------- | --------------------------------------------------------------------
|June 30, 2002      | 174.8                                                                              | 174.9                                                               | 30.8                                                                
|September 30, 2002 | 166.6                                                                              | 162.2                                                               | 34.0                                                                
|December 31, 2002  | 160.7                                                                              | 151.7                                                               | 37.3                                                                
|March 31, 2003     | 153.7                                                                              | 142.5                                                               | 43.8                                                                
|June 30, 2003      | 133.1                                                                              | 133.8                                                               | 48.2                                                                
|September 30, 2003 | 124.2                                                                              | 125.6                                                               | 48.5                                                                
|December 31, 2003  | 116.2                                                                              | 117.9                                                               | 53.3                                                                
|March 31, 2004     | 107.5                                                                              | 109.1                                                               | 55.5                                                                
|June 30, 2004      | 130.8                                                                              | 100.9                                                               | 62.6                                                                
|September 30, 2004 | 127.9                                                                              | 93.4                                                                | 66.5                                                                
|December 31, 2004  | 125.3                                                                              | 86.4                                                                | 70.3                                                                
|March 31, 2005     | 121.8                                                                              | 81.5                                                                | 70.7                                                                
|June 30, 2005      | 120.3                                                                              | 76.9                                                                | 73.5                                                                
|September 30, 2005 | 119.8                                                                              | 72.6                                                                | 77.2                                                                
|December 31, 2005  | 117.4                                                                              | 68.5                                                                | 78.3                                                                
|March 31, 2006     | 112.6                                                                              | 64.4                                                                | 80.8                                                                
|June 30, 2006      | 112.1                                                                              | 60.6                                                                | 84.1                                                                
|September 30, 2006 | 111.2                                                                              | 57.0                                                                | 86.5                                                                
|December 31, 2006  | 110.8                                                                              | 53.7                                                                | 89.3                                                                
|March 31, 2007     | N/A                                                                                | 50.5                                                                | 91.4                                                                

|ARTICLE TWO


2.1
All terms used in this Supplemental Indenture which are defined in the Indenture and not
otherwise defined herein shall have the meanings assigned to such terms in the Indenture.


2.2
All of the provisions of this Supplemental Indenture shall be deemed to be incorporated
in, and made part of, the Indenture, and the Indenture, as amended and supplemented by
this Supplemental Indenture, shall be read, taken and construed as one and the same
instrument and shall be binding upon all the Holders.


2.3
This Supplemental Indenture may be executed in any number of counterparts, each of which
so executed shall be deemed to be an original, but all such counterparts shall together
constitute but one and the same instrument.


2.4
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.


2.5
Nothing in this Supplemental Indenture, express or implied, shall give any person, other
that the parties hereto and their successors hereunder and the Holders, any benefit or any
legal or equitable right, remedy or claim under this Supplemental Indenture. Except as
expressly supplemented or amended as set forth in this Supplemental Indenture, the
Indenture is hereby ratified and confirmed, and all the terms, provisions and conditions
thereof shall be and continue in full force and effect. The Trustee accepts the trusts
created by the Indenture, as amended and supplemented by this Supplemental Indenture, and
agrees to perform the same upon the terms and conditions in the Indenture as amended and
supplemented by this Supplemental Indenture.


2.6
The Trustee shall not be responsible in any matter whatsoever for or in respect of the
validity or sufficiency of this Supplemental Indenture, except with respect to the
execution hereof by the Trustee, or for or in respect of the recitals contained herein,
all of which are made solely by the Company and the Guarantors.


     *************

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

| |                                                                                                                                                                                                                                                                    
| | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | Arch Wireless, Inc.
Arch Wireless Holdings, Inc.
Arch Wireless Communications, Inc.
MobileMedia Communications, Inc.
Arch Wireless Operating Company, Inc.
Arch Wireless License Co., LLC
Paging Network International, Inc.
Paging Network Canadian Holdings, Inc.

| |                                           
| | ------------------------------------------
| | As to each of the foregoing:              
| | By:_________________________              
| | Name:______________________               
| | Title:________________________            
| | The Bank of New York, as Indenture Trustee
| | By:_________________________              
| | Name:______________________               
| | Title:________________________            

|Schedule I


Arch Wireless, Inc. Arch Wireless
Communications, Inc. MobileMedia Communications, Inc. Arch Wireless Operating Company,
Inc. Arch Wireless License Co., LLC Paging Network International, Inc. Paging Network
Canadian Holdings, Inc.
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------