Appendix - Dtmf, Fax & Modem Transport Modes; Dtmf/Mf Relay Settings; Fax/Modem Settings; Configuring Fax Relay Mode - AudioCodes Mediant 1000 User Manual

User's Manual
14 Appendix - DTMF, Fax & Modem
Transport Modes
14.1

DTMF/MF Relay Settings

Users can control the way DTMF/MF digits are transported to the remote Endpoint, using
the DTMFTransport/MFTransport configuration parameters. The following four modes are
supported:
DTMF/MFTransportType= 0 (MuteDTMF/MF) In this mode, DTMF/MF digits are
erased from the audio stream and are not relayed to the remote side. Instead, silence
is sent in the RTP stream.
DTMF/MFTransportType= 2 (TransparentDTMF/MF) In this mode, DTMF/MF digits
are left in the audio stream and the DTMF/MF relay is disabled.
DTMF/MFTransportType= 3 (acRelayDTMFOverRTP/ acRFC2833RelayMF) In this
mode, DTMF/MF digits are relayed to the remote side using the RFC 2833 Relay
syntax.
DTMFTransportType = 7 (acRFC2833RelayDecoderMute) In this mode, DTMF
digits are relayed to the remote side using the RFC 2833 Relay syntax. RFC 2833
digit packets that are received from the remote side are muted on the audio stream.
14.2

Fax/Modem Settings

Users may choose from one of the following transport methods for Fax and for each
modem type (V.22/V.23/Bell/V.32/V.34):
fax relay - demodulation / remodulation
bypass - using a high bit rate coder to pass the signal
transparent - passing the signal in the current voice coder
transparent with events - transparent + issues fax/modem events
When the fax relay mode is enabled, distinction between fax and modem is not
immediately possible at the beginning of a session. Therefore, the channel is in Answer
Tone mode until a distinction is determined. The packets being sent to the network at this
stage are Fax relay T.38 packets.
14.3

Configuring Fax Relay Mode

When FaxTransportType= 1 (relay mode), upon detection of fax, the channel automatically
switches from the current voice coder to answer tone mode, and then to Fax T.38 relay
mode.
When Fax transmission has ended, the reverse switching from fax relay to voice is
performed. This switching automatically mode occurs at both the local and remote
Endpoints.
The fax rate can be limited by using the FaxRelayMaxRate parameter and the ECM Fax
Mode can be enabled/disabled using the FaxRelayECMEnable parameter settings.
Version 4.6
14. Appendix - DTMF, Fax & Modem Transport Modes
263 August 2005