ABTO Software offers customizable T.38 Modem, which allows you to build a custom VoIP fax.

T.38 Modem is fax/voice modem pool + SIP endpoint.

The application has standard COM port interface.

For communication with other software it needs com0com utility (attached to installation) that creates 2 paired COM ports.

Main features of our customizable VoIP fax solution:
* T.38 protocol support;
* Ability to send/receive faxes in voice mode;
* Ability to send/receive color/multipage faxes.

You can find more details on www.voipsipsdk.com