I have a CUBE and third party SIP/IVR system. For incoming calls as soon IVR system answers the call, the call will be dropped with 503 Service Unavailable/cause=47. I could assume and prove that this should be related to codec selection between endpoints but I want to know why.
After reviewing logs, I could see following:
CUBE sent an Invite message to CUCM with following SDP:
v=0
o=CiscoSystemsSIP-GW-UserAgent 3968 9141 IN IP4 x.x.x.x
s=SIP Call
c=IN IP4 x.x.x.x
t=0 0
m=audio 23996 RTP/AVP 8 100 101
c=IN IP4 x.x.x.x
a=rtpmap:8 PCMA/8000
a=rtpmap:100 X-NSE/8000
a=fmtp:100 192-194,200-202
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ptime:20
a=X-sqn:0
a=X-cap: 1 audio RTP/AVP 100
a=X-cpar: a=rtpmap:100 X-NSE/8000
a=X-cpar: a=fmtp:100 192-194,200-202
a=X-cap: 2 image udptl t38
After this, CUCM sent an Invite to IVR system with following:
v=0
o=CiscoSystemsCCM-SIP 404122957 1 IN IP4 y.y.y.y
s=SIP Call
c=IN IP4 z.z.z.z
t=0 0
m=audio 17376 RTP/AVP 0 101
a=rtpmap:0 PCMU/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
We could see CUBE sent PCMA but CUCM sent out PCMU. Is this negotiation in correct way?
After some SIP communications, the third party SIP system sent 200 OK with following SDP and CUCM confirmed this with an ACK:
o=+123456789 12367 12367 IN IP4 10.10.1.1
s=Media Session
c=IN IP4 10.10.1.1
t=0 0
m=audio 18004 RTP/AVP 0 101
a=fmtp:101 0-11
a=rtpmap:0 PCMU/8000/1
a=rtpmap:101 telephone-event/8000
After sending ACK, CUCM sent 503 Service Unavailable/cause=47 to the CUBE.
CUBE and IVR have their own device pools and their device pools have different region with same codec 64 Kb/s (G. 722, G.711). However, in CUCM logs I could see followings:
30702338.007 |22:22:47.112 |AppInfo |DET-MediaManager-(1823141)::preCheckCapabilities, region1=MyRegion1, region2=MyRegion2, Pty1 capCount=4 (Cap,ptime)= (4,30) (257,30) (259,30) (261,30), Pty2 capCount=1 (Cap,ptime)= (2,20)
Here I could see, CUCM wanted to find a xcoder, but because this is not configured tried to use the MTP from MRG. I have already a software MTP.
Here are my queries regarding CUCM and codecs:
- Why did send CUCM PCMU to IVR, even the CUBE send PCMA?
- Why did use CUCM (4,30) (257,30) (259,30) (261,30), when all codec in CUCM are enabled?
4 = G711mu-law
257= RFC2833_DynPayload
259 = PassThrough
261 = Inband_DTMF_RFC2833
- Why did CUCM use packet size 30, however preferred packet size service parameters is 20.
- Using a transcoder could solve this issue or using a hardware MTP should solve this issue?
Currently I have software MTP.
Regards
