Exhibit B
JOINT FILING AGREEMENT
The undersigned hereby agree that the Statement on Schedule 13G/A, dated
February 27, 2006 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: February 28, 2006
POTOMAC CAPITAL MANAGEMENT LLC
By: /s/ Xxxx X. Xxxxx
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Xxxx X. Xxxxx, Managing Member
POTOMAC CAPITAL MANAGEMENT INC.
By: /s/ Xxxx X. Xxxxx
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Xxxx X. Xxxxx, President
XXXX X. XXXXX
By: /s/ Xxxx X. Xxxxx
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Xxxx X. Xxxxx
