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MTP Required on SIP Trunk Break MC MoH

We are running a new deployment of CUCM 9.1.1.  We are running SIP trunks to our PSTN gateways and use PRI as connectivity to the PSTN carrier.  The problem we are running into is that when we have the MTP Required check box checked on SIP trunk to our gateways, we are unable to play our customized MoH locally on the LAN of a particular site.  We are using the Barix Instreamer to broadcast a mulicast MoH stream on the local LAN to support a local market customized Marketing messages to our customers.  We are not able to get this multicast MoH stream to play when calls placed to or from the PSTN.  We can hear it on calls internally when placed on hold.  We had the MTP required check box unchecked per Cisco as this allows this multicast MoH stream to play to calls to or from the PSTN when placed on hold.  However, when we do not have the MTP required check box selected, we are getting intermitent dropped calls and calls with one way audio.  Since I selected the MTP required for the SIP trunk, I have not had any reports or dropped calls or audio problems on any of the 4 sites that this has been happening at.

Any insight or ideas would be greatly appreciated.


VIP Super Bronze

MTP Required on SIP Trunk Break MC MoH


The first thing to do is to ivestigate why your calls are dropping. Inserting an MTP is not a solution for me. It can create more problems..faxing comes to mind and now as you can see multicats MOH. You need to dig deeper to see why your cluster requires an MTP. To do this..

1.Give us a detailed description of your call flow. What endpoints are involved in your setup

2. Send us a show run of your PSTN gateway

3. Send us detailed CUCM traces for scenarios when you have a call failure

4. send us debug ccsip messages on your PSTN gateway

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