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MTP Required on H.323 Gateway

marknigh1
Level 1
Level 1

I ran into an issue recently that for any supplementary services (hold, transfer, call park) to be used I had to check the MTP required check box on an h.323 gateway. Unfortunately, by checking this check box all calls are getting forked through the CallManager since that is where my MTP's are configured.

The call flow is straight forward with a call coming into a analog or PRI gateway to a local IP phone? These gateways are remote to the Callmanagers. CallManager is located in a Data Center with no PSTN or voice gateway access. I verified that the calls are forking to CallManager by clicking on the IP address of a phone I am make a call into from a local gateway and noticed that the stream's source was the Callmanager IP address and NOT the local gateway.

I have asked several Engineer on my team that have all stated they have ever had to check that box to get supplementary services to be used. Cisco TAC is stating that I need to have this checked for hold, etc to work. I have configured software based MTP on the remote voice gateways for now, but software based MTPs are single codec only so the calls are not able to be transferred to another remote location since my regions state g.729.

Your help is appreciated. I can't believe that I have to fork all calls to CallManager to get hold. call park to work!!!

5 Replies 5

paolo bevilacqua
Hall of Fame
Hall of Fame

That is correct, you have to enable MTP for supplementary services to work.

You can dig and study to find why that is the case, but it is, and there is no way around it.

Thanks for the response.

The interesting thing is that I have several deployments that do not have that checked and it is working along with many other Engineers with many other deployments that do not have that checked either.

Is it a Callmanager version -> IOS version combination?

You can cross check the versions you are using and come to interesting results that even TAC may not know.

My experience recently, with a recent IOS and CM, hold, transfer etc were working without MTP.

As I added a TCL/IVR script that complicated the call flow, MTP had to be enabled.

This is my experience too. This is my first project where I had to check the checkbox. All other projects are working without it. I think I will open a ticket with Cisco TAC to see if I can get a better understanding. This is crazy.

Is it possible to route a particular call through MTP by forking it through Call Manager instead enabling it for all calls? I believe that if its enabled on the gateway all the calls will be forked through the Call Manager. If I make the MTP's unavailable for the rest of the phones will it help?

Can we run Cisco IP Voice Media Streaming Application on a standalone server which can be locally made available at remote locations where the gateways are present, instead of forking all the calls through Call Manager which is present at a central location connected through WAN.

Please advice.

Thank you.

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