AudioCodes Mediant 3000 User Manual page 564

that G.711 is listed first. The device removes the coders (i.e., G.723) from the SDP
that do not appear in the Allowed Audio Coders Group for coder restriction.
m=audio 6050 RTP/AVP 0 8 18 96
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:18 G729/8000
a=fmtp:4 annexa=no
a=rtpmap:96 telephone-event/8000
a=fmtp:96 0-15
a=ptime:20
a=sendrecv
2. On the outbound leg for the outgoing SDP offer: The SDP offer now includes only the
G.711 and G.729 coders due to the coder restriction process on the incoming SDP
offer (see Step 1).
a. The device adds the extension coder to the SDP offer and therefore, the SDP
offer now includes the G.711, G.729 and G.726 coders.
m=audio 6050 RTP/AVP 0 8 18 96 96
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:18 G729/8000
a=rtpmap:96 G726-32/8000
a=fmtp:4 annexa=no
a=rtpmap:96 telephone-event/8000
a=fmtp:96 0-15
a=ptime:20
a=sendrecv
b. The device applies coder restriction to the SDP offer. As the Allowed Audio
Coders Group for coder restriction includes the G.723, G.726, and G.729 coders,
the device allows and keeps the G.729 and G.726, but removes the G.711 coder
as it does not appear in the Allowed Audio Coders Group for coder restriction.
m=audio 6050 RTP/AVP 18 96 96
a=rtpmap:18 G729/8000
a=rtpmap:96 G726-32/8000
a=fmtp:4 annexa=no
a=rtpmap:96 telephone-event/8000
a=fmtp:96 0-15
a=ptime:20
a=sendrecv
3. The device includes only the G.729 and G.726 coders in the SDP offer that it sends
from the outgoing leg to the outbound SIP entity. The G.729 is listed first as the
Allowed Audio Coders Group for coder restriction takes precedence over the
extension coder.

To configure coder transcoding:
1. In the Coders Group Settings table, configure a Coders Group for extension coders.
For more information, see ''Configuring Coder Groups'' on page 385.
2. In the IP Profile table, configure the IP Profile associated with the SIP entity:
a. Assign the Coders Group to the IP Profile, using the 'Extension Coders'
parameter (SBCExtensionCodersGroupID).
b. Enable extension coders by configuring the 'Allowed Coders Mode' parameter to
Restriction or Restriction and Preference.
User's Manual 564
Mediant 3000
Document #: LTRT-89730