As enterprises consolidate voice, video, and data applications on a single network infrastructure, the benefits of Fax over IP (FoIP) are becoming increasingly persuasive. Organizations that have transitioned to Voice over IP (VoIP) are becoming increasingly aware that routing faxes over their IP network results in costs savings and productivity benefits.

What is T.38 Fax over IP?

T.38 is the protocol that describes the process for sending and receiving faxes in real-time over a packet network – i.e. a VoIP network. T.38 is designed to preserve the traditional fax experience and ensure that faxes are successfully sent and received in real-time as a point to point communication.

Faxing over an IP network requires a FAXCOM Server with a Brooktrout SR140 software license or a Brooktrout TR1034 fax board, and a VoIP network with a T.38 gateway that supports Session Initiation Protocol (SIP) or H.323 call control. The T.38 gateway acts as a bidirectional bridge between the telephone and IP networks, and sits between the fax server solution and the destination fax device. On the internal VoIP network, the T.38 gateway sends and receives T.30 data wrapped in T.38 packets, while externally it sends and receives T.30 fax signaling over the PSTN.

Note that T.30, the same protocol used for faxing over the telephone network, remains at the heart of every IP fax connection. The FAXCOM Fax Server (via the SR140 application or the TR1034 board) is responsible for negotiating, synchronizing and communicating with the destination fax device.

Implementing T.38 FoIP

In a traditional fax server implementation the fax server includes fax boards that connect directly to the phone network (PSTN) through a local PBX or to the CO (Central Office). The fax server sends and receives faxes over the phone network to remote fax devices.

In a T.38 FoIP implementation, the fax server is “boardless” -- running only the fax server software licenses. The IP fax server routes faxes to T.38-enabled endpoints on the VoIP network, such as VoIP routers or gateways. The VoIP routers or gateways then connect to the phone network to send and receive faxes to remote fax devices. Even though the VoIP network is the endpoint sending faxes over the phone network, the fax communication is still a point-to-point, real-time delivery from the IP fax server.

Implementation of T.38 FoIP requires a VoIP implementation with routers and gateways configured for T.38 support. It is generally necessary for customers to configure their VoIP network to support T.38 FoIP – it is not a default feature of the VoIP implementation. Customers will need access to technical resources able to configure their VoIP routers and gateways to assist Biscom with the implementation.