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ERROR: SDP m line (audio) decoding failed

Symptom:

With the Dialogic® Integrated Media Gateways, calls may fail with the following errors in the call trace:

18:21:36.760 SIP (W) SIP Err: SDP Decoding Failed at /ngcsp/src/comps/sigSIP/src/codec/sdp/src/sdp_dec.c, 1940
18:21:36.760 CALL(SIP) (00:00003:00) ERROR: SDP m line (audio) decoding failed
18:21:36.760 SIP (W) SIP Err: SDP Decoding Function Failed at /ngcsp/src/comps/sigSIP/src/codec/sdp/src/sdp_dec.c, 952
18:21:36.760 SIP (W) SIP Err: SDP Decoding Function Failed at /ngcsp/src/comps/sigSIP/src/codec/sdp/src/sdp_dec.c, 154
18:21:36.760 SIP (W) SIP Err: SDP Parsing Failed 1 at /ngcsp/src/comps/sigSIP/src/tuc/l3ua/src/l3ua_af110.c, 432

Reason for the issue:

In the offer in the SDP there are no codecs listed in the m= line on the incoming INVITE

---> [192.168.4.1, 5060]
INVITE sip:14001@192.168.4.3:5060;user=phone SIP/2.0\r\n
Allow: INVITE, BYE, REGISTER, ACK, OPTIONS, CANCEL, SUBSCRIBE, NOTIFY, INFO, REFER, UPDATE\r\n 
Call-Id: 6c48-401-912010182136-IMGA-0-192.168.4.3\r\n 
Contact: <sip:4098@192.168.4.3:5060>\r\n 
Content-Length: 139\r\n 
Content-Type: application/sdp\r\n 
CSeq: 1 INVITE\r\n 
Expires: 300\r\n 
From: '\261Channel 98'<sip:4098@192.168.4.3;user=phone>;
tag=95ffcd055e0f78f7d5d397020e89288d1e6a7647\r\n 
Max-Forwards: 70\r\n 
Organization: Dialogic\r\n 
Session-Expires: 1800\r\n 
Supported: path, replaces, timer, tdialog\r\n 
To: <sip:15857844001@192.168.4.1:5060;user=phone>\r\n 
User-Agent: Dialogic-SIP/10.5.3.51741 IMGA 0\r\n 
Via: SIP/2.0/UDP 192.168.4.1;branch=z9hG4bK000003fa-b316
8b93,SIP/2.0/UDP 192.168.4.3:5060;branch=z9hG4bK-42f7-12
85957296-4998-393\r\n 
\r\n 
v=0\r\n 
o=Dialogic_SDP 1 0 IN IP4 192.168.4.3\r\n 
s=Dialogic-SIP\r\n 
c=IN IP4 192.168.4.13\r\n 
t=0 0\r\n 
m=audio 8004 RTP/AVP\r\n 
a=silenceSupp:off - - - -\r\n 

Below is an example of a correct m= line where 0 and 18 are the codecs:

m=audio 8000 RTP/AVP 0 18\r\n 

Fix / Solution:

Codecs must be added in the IP Bearer Profile in Dialogic® Gate Control Element Management System (GCEMS) Clientview (IMG 1004 or IMG 1010) or the WebUI (IMG 2020) as described in the links below in the IMG documentation.

IMG 1004 / IMG1010: http://www.dialogic.com/webhelp/IMG1010/10.5.3/WebHelp/vocoderentry.htm

IMG 2020: http://www.dialogic.com/webhelp/BorderNet2020/2.2.0/WebHelp/vocoderprofile.htm

Product List

Dialogic® IMG 1004 Integrated Media Gateway
Dialogic® IMG 1010 Integrated Media Gateway
Dialogic® IMG 2020 Integrated Media Gateway (IMG 2020), formerly referred to as Dialogic® BorderNet™ 2020 Session Border Controller