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Cisco AS5300 and Lync 2010 sip trunk

Hello! We have a Microsoft Lync Server 2010 Enterprise Voice deployed. In order to reach PSTN we have received a sip-trunk from our ITSP. The inboud and outbound calling works fine except one thing - it is no possible to put a call in Lync on hold. I wanted to confirm, that our ITSP's VoIP Gateway Cisco AS5300 supports the call hold from Lync.

Firmware version: Cisco IOS (tm) 5300 Software (C5300-JS-M), Version 12.3(26), RELEASE SOFTWARE (fc2)

There are no errors on Cisco debug logs. There are no errors on Lync Server Mediation Server Logs.

Guys, need your help urgently!



Why aren't you asking the carrier this question?

Post the SIP dialog here for the entire call and note the timestamp you attempt to place the call on hold. SIP provides different methods of putting a call on hold. It's possible Lync is trying one that the AS5300 can't support.

Jonathan, hi!

Thank you for your reply!

I have already asked our ITSP. They dont no and see no errors in their Cisco debug log.

Here is the WireShark call flow:

Here is the complete log of the call:

I am trying to put a call on hold on the 23rd second and 27th.

Looking forward for help of community.    

What happens in Lync when you try to put the call on hold? The PCAP file you sent appears to place the call on hold with a re-INVITE using a=inactive SDP in packet 964 to which the AS5300 200 OKs and Lync ACKs the 200 OK. At first glance it appears that the AS5300 does as it's told here and keeps the call up without an active RTP/RTCP stream.

Technically, Lync doesn't seem to comply with RFC3264 since it is changing from sendrecv to inactive which doesn't appear to be valid if I'm reading the RFC correctly. Either way the AS5300 doesn't seem to have an issue with it.

When i try to put a call on hold in Lync (soft phone) the following happens: the message appears stating that it is not possible to put a call on hold. And then Lync mutes the microphone and speakers. After i manually enable them - there are no sounds between the caller and callee. The complete silence.

I can't explain why Lync reacts that the call is not on hold. I don't pretend to be an expert in SIP so I may be misreading the SDP response from the AS5300. A Microsoft engineer should probably look at it to explain why Lync has issues with the reply but then ACKs it without complaint.

As for why you get no audio after manually unmuting: Lync never re-INVITEd to a=sendrecv. As far as the AS5300 was concerned the call was still on hold. The next command from Lync was a BYE to tear down the call.

Unless another person here spots what I'm missing in that thread it is probably time to cough up the coin for a MS support ticket.

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