AudioCodes E-SBC User Manual

CHAPTER15 Media
Mediant 1000 Gateway & E-SBC | User's Manual
➢ To configure automatic T.38 mode:
1. Open the Gateway General Settings page (Setup menu > Signaling & Media tab > Gateway
folder > Gateway General Settings), and then from the 'Fax Signaling Method' drop-down list
(IsFaxUsed), select No Fax:
2. On the Fax/Modem/CID Settings page, configure the 'Fax Transport Mode' parameter to T.38
Relay [FaxTransportMode = 1].
3. Configure the following optional parameters:
● 'Fax Relay Redundancy Depth' [FaxRelayRedundancyDepth]
● 'Fax Relay Enhanced Redundancy Depth' [FaxRelayEnhancedRedundancyDepth]
● 'Fax Relay ECM Enable' [FaxRelayECMEnable]
● 'Fax Relay Max Rate' [FaxRelayMaxRate]
Fax over IP using T.38 Transmission over RTP
The device supports Fax-over-IP (FoIP) transmission using T.38 over RTP, whereby the T.38
payload is encapsulated in the RTP packet, instead of being sent in dedicated T.38 packets (out-of-
band). To configure this support, set the coder type to T.38 Over RTP.
To indicate T.38 over RTP, the SDP body uses "udptl" (Facsimile UDP Transport Layer) in the
'a=ftmp' line. The device supports T.38 over RTP according to this standard as well as according to
the AudioCodes proprietary method:
■ Call Parties belong to AudioCodes Devices: T.38-over-RTP method is used, whereby the
device encapsulates the entire T.38 packet (payload with all its headers) in the sent RTP. For
T.38 over RTP, AudioCodes devices use the proprietary identifier "AcUdptl" in the 'a=ftmp' line
of the SDP. For example:
v=0
o=AudioCodesGW 1357424688 1357424660 IN IP4 10.8.6.68
s=Phone-Call
c=IN IP4 10.8.6.68
t=0 0
m=audio 6080 RTP/AVP 18 100 96
a=ptime:20
a=sendrecv
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=rtpmap:100 t38/8000
a=fmtp:100 T38FaxVersion=0
a=fmtp:100 T38MaxBitRate=0
a=fmtp:100 T38FaxMaxBuffer=3000
a=fmtp:100 T38FaxMaxDatagram=122
a=fmtp:100 T38FaxRateManagement=transferredTCF
a=fmtp:100 T38FaxUdpEC=t38UDPRedundancy
a=fmtp:100 AcUdptl
a=rtpmap:96 telephone-event/8000
a=fmtp:96 0-15
■ AudioCodes Call Party with non-AudioCodes Party: The device uses the standard T.38-
over-RTP method, which encapsulates the T.38 payload only, without its headers (i.e.,
includes only fax data) in the sent RTP packet (RFC 4612).
The T.38-over-RTP method also depends on call initiator:
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AudioCodes E-SBC Specifications

General

Brand	AudioCodes
Model	E-SBC
Category	Gateway
Language	English