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.?
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.
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.
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