A repository and one-stop location for everything related to Fax over IP (FoIP) and Cisco voice products
Getting fax communications to work successfully and reliably in IP environments can be more challenging than VoIP. Fax is modulated data and is therefore markedly different than voice. These differences must be taken into account and FoIP should not be treated like VoIP. From QoS to the underlying transport protocols to switchover mechanisms, dealing with FoIP is full of pitfalls and gotchas. The aim of this wiki page is to demystify fax communications in IP networks and provide a comprehensive reference page for anything related to FoIP."
Relay demodulates fax communications and passes the fax data across the IP network using special relay protocols. Cisco voice gateways generally support two types of fax relay, standards-based T.38 fax relay and the pre-standard, propriatary Cisco fax relay.
The Cisco fax server is simply an OEM of the Captaris RightFax product with a Dialogic fax engine (made up of a hardware-based fax board or the software-based SR140 solution). Integrating via T.38 with Cisco voice gateways and Unified CM, the Cisco fax server handles the faxing piece of a Unified Communications solution.
Windows Fax Service is an off-the-shelf component from Microsoft. When installed on Windows Server 2003/2008 the Service is available for all computers in the domain. There is third pary software that integrates Windows Fax Service with T.37-capable integrated services routers, see http://www.sandlerco.com/t37fsp4cisco.htm for details.