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CUCM Lync SIP trunk "MTP Required" using 9951

Answered Question
Apr 7th, 2014
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Hi,

I have this problem at one of my customers, they have Cisco ucm 8.6 with a SIP trunk to Lync 2013 and they are using Lync online meeting or something.

We are using early offer on the SIP trunk, calls from ISDN (H.323 gateway) to lync online meeting works fine, calls from CIPC and 7942/7962 phones works fne, but calls from 9951 SIP phones does not work.

The only way to get the 9951 phones to work is to check MTP required on the trunk or on the 9951 devices. But as i can read in the documentation it should work from SIP phones with out "MTP Required" checked.

I have attached some logging from the UCM i am calling from device 8227 to 9957 which is being translated to +61300578257.

Has anyone an idea to what could fix this.? 

Attachment: 
Correct Answer by Brian Meade about 3 years 4 months ago

If the video codecs being offered are the issue, you could put the SIP Trunk in a region with 0 video bandwidth so those capabilities are automatically stripped out.

Correct Answer by Suresh Subramanian about 3 years 4 months ago

Hello David,

Yes, you are right. Early Offer configurations on SIP profile apply to SIP trunk calls. These configurations do not affect SIP line side calls.

So as guessed, the video capabilities are not supported/accepted by the other end Lync server.

There should be some settings in Lync side to accept the incoming video parameters. Please check with the Lync Team.

 

If there is no video calls used in your environment, then we can disable the video capabilities for all the phones as a workaround from cisco side.

 

//Suresh

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Suresh Subramanian Mon, 04/07/2014 - 04:46
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Hello David,

Have you enabled Early Offer on the SIP Profile associated with the 9951 devices?

 

This is the Invite message sent out  to Lync Mediation Server.

 

20:26:01.951 |//SIP/SIPTcp/wait_SdlSPISignal: Outgoing SIP TCP message to 10.28.3.27 on port 5060 index 85536
[2447236,NET]
INVITE sip:[email protected]:5060 SIP/2.0
Via: SIP/2.0/TCP 10.28.144.1:5060;branch=z9hG4bK188e2ad68e4a
From: "8227 - David Winther" <sip:[email protected]>;tag=774354~a38ed899-b2b2-447f-81eb-bf519bcb3ba3-46180351
To: <sip:[email protected]>
Date: Mon, 07 Apr 2014 10:26:01 GMT
Call-ID: [email protected]
Supported: timer,resource-priority,replaces
Min-SE:  1800
User-Agent: Cisco-CUCM8.6
Allow: INVITE, OPTIONS, INFO, BYE, CANCEL, ACK, PRACK, UPDATE, REFER, SUBSCRIBE, NOTIFY
CSeq: 101 INVITE
Expires: 180
Allow-Events: presence
Supported: X-cisco-srtp-fallback,X-cisco-original-called
Cisco-Guid: 0046090240-0000065536-0000144256-0026221578
Session-Expires:  1800
P-Asserted-Identity: "8227 - David Winther" <sip:[email protected]>
Remote-Party-ID: "8227 - David Winther" <sip:[email protected]>;party=calling;screen=yes;privacy=off
Contact: <sip:[email protected]:5060;transport=tcp>;video;audio;video
Max-Forwards: 69
Content-Type: application/sdp
Content-Length: 765

v=0
o=CiscoSystemsCCM-SIP 774354 1 IN IP4 10.28.144.1
s=SIP Call
c=IN IP4 10.100.145.120
b=TIAS:384000
t=0 0
m=audio 32400 RTP/AVP 9 124 0 8 116 18 101
a=rtpmap:9 G722/8000
a=ptime:20
a=rtpmap:124 iSAC/16000
a=rtpmap:0 PCMU/8000
a=ptime:20
a=rtpmap:8 PCMA/8000
a=ptime:20
a=rtpmap:116 iLBC/8000
a=ptime:20
a=maxptime:20
a=fmtp:116 mode=20
a=rtpmap:18 G729/8000
a=ptime:20
a=fmtp:18 annexb=no
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
m=video 28314 RTP/AVP 126 97
b=TIAS:320000
a=rtpmap:126 H264/90000
a=fmtp:126 profile-level-id=42801E;packetization-mode=1;level-asymmetry-allowed=1
a=rtpmap:97 H264/90000
a=fmtp:97 profile-level-id=42801E;packetization-mode=0;level-asymmetry-allowed=1
a=imageattr:* recv [x=640,y=480,q=0.50]

 

Lync disconnecting the call with 400 Bad request which means Lync is not accepting something in the above INVITE message, I guess the Lync is not accepting the highlighted part of the message.

 

could you  try disabling the video capabilities on one phone and check the behavior please?

 

May be we can compare the working & Nonworking SIP logs and see what is wrong.

 

//Suresh

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David Winther Mon, 04/07/2014 - 06:12
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Hi Suresh,

 

Thanks for the reply. 

As i can read the early offer is just for trunks.

But you are right about the video, if i disable the video on the 9951 it works.

/David

Correct Answer
Suresh Subramanian Mon, 04/07/2014 - 06:49
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Hello David,

Yes, you are right. Early Offer configurations on SIP profile apply to SIP trunk calls. These configurations do not affect SIP line side calls.

So as guessed, the video capabilities are not supported/accepted by the other end Lync server.

There should be some settings in Lync side to accept the incoming video parameters. Please check with the Lync Team.

 

If there is no video calls used in your environment, then we can disable the video capabilities for all the phones as a workaround from cisco side.

 

//Suresh

Please rate all the useful posts.

David Winther Tue, 04/08/2014 - 03:47
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Hi Suresh,

Thanks for helping, i will go to the Lync team to see if they can accept the incomming parameters.

 

/David

Correct Answer
Brian Meade Tue, 04/08/2014 - 07:36
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If the video codecs being offered are the issue, you could put the SIP Trunk in a region with 0 video bandwidth so those capabilities are automatically stripped out.

David Winther Tue, 04/08/2014 - 11:38
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That sounds like a good idea, i will try that tomorrow.

Thanks Brian

David Winther Wed, 04/09/2014 - 04:07
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Hi Brian,

 

It did work as you described, so that was actually a better solution then they still can have video enabled on their phones.

Thanks 

Suresh Subramanian Wed, 04/09/2014 - 04:29
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it is a good to know point Brian. Thanks for that. have a question here. what if we need to make a video calls between Cisco and Lync over SIP Trunk?

Brian Meade Wed, 04/09/2014 - 09:32
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If you need the video calls, someone will need to investigate why the Lync Mediation server is sending the 400 Bad Request when video codecs are sent.

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