VOCAL’s T.38 Fax over IP (FoIP) software allows the use of ordinary group 3 facsimile as well as high speed V.34 machines on modern internet protocol (IP) networks, permitting ATAs or other FoIP products to relay calls through a VoIP service. Without T.38, successful calls can be placed, but these can be less reliable than facsimile transmissions through an ordinary telephone line. With the T.38 protocol, the user should not even know that a VoIP service is being used instead of a land line connection.
The T.38 software supports:
V.34 fax data channel – full and half duplex modulation for data rates in the range of 2400 bps to 33600 bps.
V.34 fax control channel – 1200/2400 bps modulation for use with half duplex procedures
V.17 - 7200, 9600, 12,000 and 14,400 bps trellis coded modulation
V.29 - 7200 and 9600 bps modulation
V.27ter - 2400 and 4800 bps modulation
V.21 Channel 2 - 300 bps modulation
- Fully integrated Group 3 Facsimile processing system
- Configurable to support both TCP/IP and/or UDP/IP modes of data transmission
- Configurable to support UDPTL forward error correction messages
- Configurable high speed training mechanism – Local TCF generation or TCF transmitted between end-terminals
- Optimized for high performance on leading edge DSP architectures
- Group 3 Facsimile store-and-forward features available
- Group 3 Facsimile End Terminal operation with direct T.38 protocol interface available
- Complete VoIP systems available (speech codecs, DTMF tokens, silence tokens, etc.)
- Speech codecs include V.34 fax, G.723, G.729, G.729A, GSM, G.728, G.726/G.721
- Complete data modem systems available (through V.90/V.42bis and V.34fax/T.30)
- Multiple ports can be executed on a single DSP
- The SIP protocol is used to establish sessions between two (or more) entities, the T.38 fax call flow is normally indicated by SDP entries in the initial SIP INVITE message.
- T.38 Fax over IP modules can be combined with VOCAL’s SIP and network stacks to obtain seamless voice and/or relay operation from call startup to disconnect. Complete facsimile server call control is also available and can be combined with our real-time Group 3 fax store and forward module.
- Alternatively, when integrated with VOCAL’s SIP/T.30 modules and TCP/IP network stack, a standalone internet-ready T.38 facsimile end terminal can be realized. In this configuration the modulation layer is unnecessary and so interoperability with high speed V.34 fax based terminals can be achieved without the need of digital signal processing.
- ANSI C, assembly, and source code available