<DOCUMENT>
<TYPE>EX-99
<SEQUENCE>3
<FILENAME>s11-5748_ex99b.txt
<DESCRIPTION>EXHIBIT 99B
<TEXT>
Exhibit B



                             JOINT FILING AGREEMENT

                     The undersigned hereby agree that the Statement on Schedule
         13G, dated July 14, 2005 with respect to the shares of Class A Common
         Stock of Numerex Corp. and any further amendments thereto executed by
         each and any of us shall be filed on behalf of each of us pursuant to
         and in accordance with the provisions of Rule 13d-1(k)(1) under the
         Securities Exchange Act of 1934, as amended.

                     This Agreement may be executed in separate counterparts,
         each of which shall be deemed an original, but all of which shall
         constitute one and the same instrument.

         Dated: October 7, 2005


                                   POTOMAC CAPITAL MANAGEMENT LLC

                                   By:   /s/ Paul J. Solit
                                        ----------------------------------
                                         Paul J. Solit, Managing Member

                                   POTOMAC CAPITAL MANAGEMENT INC.

                                   By:   /s/ Paul   J. Solit
                                        ----------------------------------
                                         Paul J. Solit, President



                                   PAUL J. SOLIT

                                    By:   /s/ Paul J. Solit
                                        ----------------------------------
                                          Paul J. Solit

</TEXT>
</DOCUMENT>
