in reply to
Help With Custom War Dialer
Presuming your dialing modem has a fax modem, you might see if you could find a wintendo version of something like hylafax. Baring that, you could look for what AT commands to send your fax modem to make it dial as if sending a fax and see if the other end answers to that correctly.
Update: After re-reading that I wasn't exactly clear. What I meant was using something like hylafax to try and send a fax to each of your discovered phone numbers and see if it successfully delivers it or not.