[cisco-voip] SIP Issue

[Jason Granat]

After looking at the SDP header I found the difference between a good and bad call was video capabilities. Seems there is a TAC bug regarding the issue, but even using their workaround doesn't work. With the workaround the call doesn't complete and I think it is because there is a video attribute that cannot be removed.

Enhancement to Block Video Codec from Voice class Codec , Open CSCtb10108<http://tools.cisco.com/Support/BugToolKit/search/getBugDetails.do?method=fetchBugDetails&bugId=CSCtb10108>
CUCME TAC Issues<http://uc500.com/aggregator/sources/10> - Mon, 11/02/2009 - 12:36
Symptom: Telco ===(SIP)===CME===Phone with VT The video codec cannot be disabled on the voice-class codec. The supported codec will be passed to telco if there is no video codec configured on the voice-class codec. Currently, there is option to disable the video codec on the voice class codec. However, it caused some issue when customer make normal voice call to telco via SIP trunk from the SCCP Video Phone. The SIP INVITE message will announce the video codec to Telco when the call being made from Video endpoint. Thus, If the VOIP telco does not support Video Codec, it caused the telco to drop the call when CME announce the video codec within the INVITE Message. This enhancement request aims to add a CLI/Method to filter/Remove the Video Codec before send to any VOIP Trunk.
Conditions: - Telco does not have video call capability - Make Normal Voice call from SCCP Video endpoint
Workaround: 1. Use SIP profiles to change the SDP to indicate no video support - note this cannot remove the m-line completely but make it a "zero m-line" which indicates SIP video is not supported. The "a=" header is removable by SIP profiles. Below is an example for an outbound call: voice class sip-profiles 2 request INVITE sdp-header Video-Media modify "m=video.*" "m=video 0 RTP/AVP 34 119" request INVITE sdp-header Video-Attribute remove request INVITE sdp-header Video-Bandwidth-Info remove ! dial-peer voice 10000 voip session protocol sipv2 voice-class sip profiles 2 2. Disable CUVA


From: cisco-voip-bounces at puck.nether.net [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Jason Granat
Sent: Thursday, November 19, 2009 10:01 AM
To: cisco-voip at puck.nether.net
Subject: [cisco-voip] SIP Issue

This is a little off-topic but to me still relevant in my learning process. I'm not looking for someone to solve this specific problem, in and of itself. I need to know if I am doing something wrong. I want to understand the technology. I have a voice lab to pass, you know... :)

Sooo... I've had this issue with a UC520. On CME 7.x or greater I have an issue with outbound calls through my SIP carrier having one-way audio, only when 'service phone videoCabaility' is set to 1 under telephony-service. This does not happen on CME 4.2 or lower. I ran some tests. This is all 100% reproducible every time. I am trying to pinpoint this thing with sub-nanometer precision...

Here's the basic layout. UC520 with skinny phones (796X & CIPC) with CUVA ball cams. SIP trunk to CallCentric. When the video option is off globally in telephony-service (service phone videoCapaility 0) all calls are fine. When video is enabled (service phone videoCapaility 1) calls from the skinny phones out to PSTN via CallCentric have one-way audio: the called party hears just fine but the calling party has dead air. No rx on the phone. Wireshark confirms no RTP coming back to the phone, yet signaling does. All other calls are fine, internal to internal, PSTN to internal.

I started my testing by rebooting the UC520 without modifying the config. When it came back up I was able to make outbound calls several times with 100% success, with the 'service phone videoCapability' set to 1. After roughly 5 minutes of uptime I went from 100% success to 100% failure. I rebooted again, same behavior:  5  minutes of 100 % outbound calling success, followed by 100% failure.

1'st sanity check: while it was working I copied the running config to tftp as a 'good' file. After it started failing I copied the running config to tftp as a 'bad' file. A diff on the two showed no differences. The config doesn't change between 'good' and 'bad'.

2'nd sanity check: I added the entire list of CallCentric supported codecs to my 'voice class codec'. When the call works it negotiates G711uLaw. As soon as the problem starts happening the call starts negotiating at G729r8. The call setup completes, yet one-way audio.

3'rd sanity check: I set 'service phone videoCapability' back to 0, create cnf-files, reset phones and things work again, always, without rebooting. This parameter is the only thing that changes to break or fix the issue.

4'th sanity check: I watched system uptime with the 'version' command. The problem ALWAYS starts happening at the 6 minute mark.

5'th sanity check: This only happens with IOS post 12.4(11)XW10, which has CME 4.2(0). If I roll back to 12.4(11)XW10 the problem never happens, whether video is enabled or not... NEVER!!! In fact I can only have the G711uLaw codec in my list and it still works flawlessly on this code... IOS post this release is CME version 7.x...

Aaaarrrgghhhh.....


TIA...

Jason

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