RFC 2833 Considerations

For legacy RFC 2833 inter-working to function properly, the Access Session Border Controller (A-SBC) communicates the RFC 2833 configuration to the Transcoding Session Border Controller (T-SBC) in the UAC dialog.

The following example shows an INVITE with RFC 2833 information sent from the A-SBC to the T-SBC.

INVITE sip:192.168.101.78:5060 SIP/2.0
Via: SIP/2.0/UDP 192.168.101.18:5060;branch=z9hG4bK10dspa3058b1io4rk721
Max-Forwards: 70
Call-ID: 9fc71d79b43b4b95de41acefd71a8bc4@192.168.101.78
To: sip:192.168.101.78:5060
Contact: sip:172.16.101.18
From: sip:172.16.101.18;tag=bcf80756721880b7996ccb488b6a1b2f
CSeq: 1 INVITE
Target-Dialog: 1-16881@172.16.18.5;local-tag=1;remote-tag=16880SIPpTag011;realm=net192
Acme-Codec-Policy: ;ingress;name="in-2833";allow-codecs="* ";add-codecs-on-egress="";force-ptime="disabled";packetization-time="20";dtmf-in-audio="disabled";order-codecs=""
Acme-Codec-Policy: ;egress;name="out-2833";allow-codecs="* ";add-codecs-on-egress="PCMA ";force-ptime="disabled";packetization-time="20";dtmf-in-audio="disabled";order-codecs=""
Acme-Rfc2833: ;ingress;Digit-Mode=0;PtTo=101;PtFrom=0;TransNon2833=disabled;TransNonInband=disabled
Acme-Rfc2833: ;egress;Digit-Mode=1;PtTo=101;PtFrom=0
Content-Type: application/sdp
Content-Length: 196
P-Visited-Network-ID: open-ims.test
Route: <sip:192.168.101.18:5060;lr;transport=UDP>
v=0
o=user1 53655765 2353687637 IN IP4 192.168.101.18
s=-
c=IN IP4 192.168.101.18
t=0 0
m=audio 20002 RTP/AVP 0 101
a=rtpmap:0 PCMU/8000