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                                                                    EXHIBIT 10.8

                         SOFTWARE SUBLICENSE AGREEMENT

This Software Sublicense Agreement (this "Sublicense"), is entered into as of
March 30, 2000 (the "Effective Date"), by and between Paging Network, Inc., a
Delaware corporation (hereinafter, "PageNet"), and Vast Solutions, Inc., a
Delaware corporation ("Vast") with respect to all of the software licensed to
PageNet under that certain Software License and Development Agreement dated
August 5, 1998 between TIBCO Software Inc. ("TIBCO"), as licensor, and PageNet,
as licensee, as subsequently amended (the "TIBCO License"). The parties hereby
agree as follows:

1.  LICENSE. PageNet hereby grants Vast a non-exclusive, non-transferable
    sublicense to use all of the computer software licensed to PageNet under the
    TIBCO License, in both object code and, to the extent expressly authorized
    under the TIBCO License, source code form (the "Software"), at no charge.
    Vast agrees to abide by all of the terms and conditions of the TIBCO
    License, a complete and accurate copy of which has been provided to it by
    PageNet. Notwithstanding the foregoing, Vast agrees to use the Software
    solely as provided in Section 4.A.II of Amendment No. 2 to the Software
    License and Development Agreement dated January 4, 1999 (the "Second
    Amendment").

2.  TERM AND TERMINATION. This Sublicense will begin as of the Effective Date
    and will terminate upon the earlier to occur of (i) the entering into of new
    software license agreements between PageNet and TIBCO and Vast and TIBCO, or
    (ii) the expiration of the Second Amendment as provided therein.

3.  WARRANTY AND LIMITATION OF LIABILITY. THE SOFTWARE IS PROVIDED "AS-IS", AND
    PAGENET DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING, WITHOUT
    LIMITATION, THE WARRANTIES OF FITNESS FOR A SPECIFIC PURPOSE,
    MERCHANTABILITY, TITLE AND NON-INFRINGEMENT. IN NO EVENT SHALL EITHER PARTY
    BE LIABLE TO THE OTHER FOR ANY DAMAGES ARISING OUT OF ITS USE OF THE
    SOFTWARE, INCLUDING BUT NOT LIMITED TO ANY INCIDENTAL OR CONSEQUENTIAL
    DAMAGES, WHETHER FORESEEABLE OR NOT, LOST BUSINESS OR LOST PROFITS.

4.  NON-ASSIGNMENT. Vast shall not assign, transfer or hypothecate any of its
    rights, obligations, or duties under this Sublicense, and any attempt to do
    so will be void.

5.  WAIVER. No delay in exercising or failure to exercise any right under this
    Sublicense on the part of either party shall operate as a waiver of such
    right by that party. Any waiver or modification of this Sublicense must be
    in writing and signed by both parties.

6.  ENTIRE AGREEMENT. This Sublicense contains the entire understanding of the
    parties hereto in respect of the subject matter contained herein and
    supersedes all prior agreements and understandings between the parties with
    respect to such subject matter.

7.  JURISDICTION. This Sublicense shall be governed by Texas law. Any dispute
    hereunder shall be subject to the sole jurisdiction of the state and/or
    federal courts located in the County of Dallas, Texas, and each party
    submits to the subject matter and personal jurisdiction of such courts.
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IN WITNESS WHEREOF, the parties hereto have caused this Sublicense to be
executed by their duly authorized representatives as of the Effective Date.

PAGING NETWORK, INC.                    VAST SOLUTIONS, INC.

BY: /s/ Ted Mullinix                    BY: /s/ Mark Knickrehm
    ---------------------------------       --------------------------------

NAME: Ted Mullinix                      NAME: Mark Knickrehm
      -------------------------------         ------------------------------

TITLE: President and C.O.O.             TITLE: President and C.O.O.
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The following sublicense is hereby consented to:

TIBCO SOFTWARE INC.

BY: /s/ Richard M. Tavan
    ---------------------------------

NAME: RICHARD M. TAVAN
      -------------------------------
       EXECUTIVE VICE PRESIDENT
TITLE: TIBCO SOFTWARE INC.
       ------------------------------