ICTFAX is a multi-tenant open source Fax Over IP solution for your faxing needs, ICTFAX is a web-based software solution for service providers based on open source Spandsp, Asterisk, Drupal CMS, and Astbill with advance multi-service prepaid billing capabilities and supporting G.711 pass through faxing, PSTN / T.30 based Faxing and T.38 based Fax over IP. It can be used in the following scenarios for fax over IP implementations

Email to fax
web to fax
Fax to email

Please visit http://www.ictfax.org for more details