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 1010: IMG 1010 - Vocoder Entry

IMG 2020: Vocoder Profile

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

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