RTP Stream to SIP Trunk to Exchange UM

Unanswered Question
Jun 19th, 2009

Hi NetPro -

I'm curious, suppose you set up UCM (5.X or above)to connect to MS Exchange UM via a SIP Trunk. When an IP Phone connects to Exchange UM, does the RTP audio stream go directly to the UM server, or does it pass through the CallManager?

I'm wondering what the options are to connect directly to UM if a remote site goes into SRST, assuming it still has access to the UM Server but not CallManager.

Thanks, R

I have this problem too.
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parshah Fri, 06/19/2009 - 09:33


To integrate CUCM with MS Exchange for VM, you need to have MTP Required checked on the SIP trunk. I know its true for CUCM 6.x, not sure about CUCM 7.x

So, if you have MTP required checked than the RTP will go through MTP.

Now, when you are in SRST, the call from remote office will go over PSTN and enter the HQ PSTN gateway and from the PSTN GW it will go to the MTP and then to MS Exchange.


Randall White Fri, 06/19/2009 - 09:57

Thanks, I forgot about the MTP.

Under SRST, I'm assuming that the remote site still has access to the Exchange UM server, but not the CallManager.


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