|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 I hereto (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 12% Subordinated Secured
Compounding Notes Due 2009 (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 10.21 of the Indenture shall be deleted in its entirety, and the following is
substituted in lieu thereof:


SECTION 10.21  
        Minimum EBITDA.


From
and after the Trigger Date, 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                                           | 
| | June 30, 2007      | 36.1                                           | 
| | September 30, 2007 | 35.4                                           | 

|
|

| | Quarter Ending     | Minimum Quarterly EBITDA
(dollars in millions) | 
| | ------------------ | ---------------------------------------------- | 
| | December 31, 2007  | 34.6                                           | 
| | March 31, 2008     | 33.8                                           | 
| | June 30, 2008      | 33.3                                           | 
| | September 30, 2008 | 32.5                                           | 
| | December 31, 2008  | 31.8                                           | 
| | March 31, 2009     | 31.1                                           | 

|1.2
     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.


From
and after the Trigger Date, 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                                              | 

|
|

| | Quarter Ending     | Minimum Direct Units in Service
(units in thousands) | 
| | ------------------ | ---------------------------------------------------- | 
| | June 30, 2006      | 2,566.4                                              | 
| | September 30, 2006 | 2,532.8                                              | 
| | December 31, 2006  | 2,499.7                                              | 

|1.3
     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..


From
and after the Trigger Date, 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                                             

|
|

|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)
|------------------ | ---------------------------------------------------------------- | ------------------------------------------------- | -------------------------------------------------
|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                                             
|June 30, 2007      | N/A                                                              | 47.5                                              | 92.8                                             
|September 30, 2007 | N/A                                                              | 44.6                                              | 93.8                                             
|December 31, 2007  | N/A                                                              | 41.9                                              | 94.3                                             
|March 31, 2008     | N/A                                                              | 39.4                                              | 94.8                                             
|June 30, 2008      | N/A                                                              | 37.0                                              | 95.5                                             
|September 30, 2008 | N/A                                                              | 34.8                                              | 95.7                                             
|December 31, 2008  | N/A                                                              | 32.8                                              | 96.0                                             
|March 31, 2009     | N/A                                                              | 30.7                                              | 96.3                                             

|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.
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------