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Help with H.323 to SIP calls

I have having an issue with an outside organization making an H.323 call to us.  We are an all SIP house.  I have my VCS Express set to translate the call to SIP from H.323 and when the distant end calls I can see them connect for a short time.  This is a conference call to our MCU which then calls our TCS and the destination endpoint.  The TCS begins recording and shows two connections, but the outside organization shows as a black screen with no audio.  Only their terminal ID displayed on the black screen.  The outside organization uses several conferencing systems.  They use a Polycom bridge and Microsoft Lync.  According to their Polycom support, they send their signalling and media on two separate IP's.  When I check the logs on my VCS Express I can see only one IP from them.  Additionally, I wouldn't know how to configure to combine two separate IP's into one call.  Can someone please help me with this one?

Cisco Employee

Hi Norm,

Please confirm if my understanding is correct

TCS----MCU-----sip-----VCS-C---VCS-E----H323------Polycom bridge----Lync client.

MCU calls TCS then MCU makes an outbound call to Polycom bridge using SIP, however you have configured rule to convert SIP URI to H323 and dial out via intenet. This call hits Polycom bridge where Lync has already joined the conference.

Yes, Polycom conferecing uses separate card for siganlling and media, however the OLC/SDP will contain the IP address of Media card.

Collect H323 logs on VCS-E, look for open logical channel message coming from far-end.

You will the media address in message.

Hope it helps



I think you have the order in reverse.  The call is initiated from the Lync client, so it would look like this.

Lync client---Polycom Bridge---H.323---VCSE---VCSC---SIP---MCU---MCU calls both the TCS and destination endpoint within my network.

Thanks for clarification.

However you can still collect the diagnostics logs from VCS-E and check what i haved mentioned in my previous.

In that way you can verify the signalling and media IP.


Collect the logs and post it here. I will look into it.


I would recommend to narrow down the problem. Right now you are mixing up many different issues (i.e. MCU, TCS, interoperability with thrid party product, FW traversal, etc.) and it would be a lot of head scratching to spot the problem. To find which component is not configured correctly, make a point to point call (i.e. no MCU, no TCS, etc.), if possible use a H323 endpoint otherwise use a SIP endpoint to make a test call to Lync. if it went well then bring in MCU, then bring in TCS, etc.

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