Fax T.38 And Voice Band Data Support (Bypass Mode); Table 7-1: Silence Suppression Operation - AudioCodes Mediant 1000 User Manual

CONFIG G.711
Setting
ON only if:
OFF
- a=silencesupp:on
AND
- payload 13 was
offered on both sides
OFF only if:
ON
- a=silencesupp:off

7.2.2.12 Fax T.38 and Voice Band Data Support (Bypass Mode)

Previous loads supported T.38 without MEGACO interference, if the Mediant 1000 was
configured to support T.38:
FaxTransportType should be configured to T.38 Relay.
Fax redundancy can be controlled using the configuration parameter
FaxRelayRedundancyDepth. This parameter controls only non-V21 packets. For V21
packets that carry important data, the redundancy depth is hard-coded to be 4.
The fax port is assumed to be the RTP port + 2, both for the local and remote side.
Following these rules, transition to T.38 is performed automatically upon detection.
Bypass (VBD) mode is also supported by using ini file parameters:
FaxTransportType should be configured to be Bypass.
The packetization period is configured by the parameter
FaxModemBypassBasicRTPPacketInterval.
The payload to be used is configured by the parameter FaxBypassPayLoadType and
ModemBypassPayloadType.
Support of the Fax type (T.38, Bypass or Transparent) was added to the SDP according to
the following rules:
If the Call Manager wants this call to support T.38, it should send an additional line in
the local SDP to the Mediant 1000, as in the following example:
User's Manual

Table 7-1: Silence Suppression Operation

G.723
ON only if:
- a=silencesupp:on
AND
- remote SDP does not contain
the line
a=fmtp:4 annexa=no
OFF only if:
- a=silencesupp:off
OR
- remote SDP contains the line
a=fmtp:4 annexa=no
88
Digital Mediant 1000
G.729
ON only if:
a=silencesupp:on
AND
- remote SDP does not contain
the line
a=fmtp:18 annexb=no
OFF only if:
- a=silencesupp:off
OR
- remote SDP contains the line
a=fmtp:18 annexb=no
Document # LTRT-66401