T.38 is a protocol used to transmit faxes over an IP network in real-time. This allows RelayFax to send documents to a fax terminal over the internet or an IP Network. This can be accomplished by creating a virtual fax device that can logon to a SIP-based software PBX. When connected to the PBX, the T.38 protocol is then used in conjunction with the Session Initiation Protocol (SIP) to control the fax session.
In order to use this feature, you will need to have access to either a SIP-based PBX server or a SIP service provider.
Additional Comments
Note: Currently, RelayFax can send to another T.38 modem without the need for any additional hardware, as long as your SIP-based PBX supports the codec. In order to send to a regular fax machine, your SIP provider must support Origination and Termination. You may also use hardware gateway that supports these features as well.
Note: This feature is only available on RelayFax 7.0 and above.