[cisco-voip] H.323 MTP Usage

[Tom Mc]

Thanks guys,

I'm using g.729. 'Software MTP only supports g.711', that would
explain it. I'm using dynamips in my test lab so I cannot test with a
xcode resource but it might be a possible solution.
The other option being using an IP-to-IP GW to terminate the call at
the cluster site, I was leaning this way myself but I adds a layer of
complexity that I may not get though by the weekend (wheels turn
slowly in this project).

Cheers,
Tom



On Tue, Apr 27, 2010 at 11:42 PM, Ryan Ratliff <rratliff at cisco.com> wrote:
> What codec is getting used for the calls through the MTP?  The software MTP only supports g.711 and if you are using any other codec CUCM will try to allocate a transcoder and this part sounds like it is failing based on your description.
>
> -Ryan
>
> On Apr 27, 2010, at 7:58 AM, Tom Mc wrote:
>
>> Hi guys,
>>
>> I have a query about how mtp can be implemented with h.323 gateways.
>>
>> We are going through a migration for a customer replacing a LCR solution.
>> Topology looks something like this:
>> PBX --> QSig --> 3845 --> H.323 --> CUCM 7.1 --> H.323 --> 3845 --> QSig --> PBX
>> CUCM has been configured for call routing using route patterns with
>> h.323 gateway destinations
>>
>> This solution has been implemented internationally for about 40 sites
>> all with 'any to any' connectivity which has not been a problem.
>> We now need to cutover Australia, and I have just been told that
>> routing to the other 40 sites at this point in time is not possible
>> and that media traffic will need to be routed via the CUCM cluster.
>>
>> I've tried to lab up this solution (replacing the pbx with ip phones)
>> trying to get the gateways to use an MTP (which is registered) and
>> thus forcing the media stream out to the internationally hosted CUCM
>> cluster.
>>
>> Ticking the box "Media Termination Point Required" in the gateway
>> config and assigning a MRGL with the CUCM software MTP's does not seem
>> to work.
>> Wireshark shows the media stream from GW to GW not GW to CUCM to GW as expected.
>> Setting the service parameter  "Fail Call If MTP Allocation Fails" to
>> true, predictably ends the call on answer attempt.
>>
>> Is what I am attempting to do possible with the CUCM software MTP's?
>> Do I need hardware resources to do this?
>>
>> The "Help, this page" on the gateway config page tells me the
>> following (which sort of tells me that this is not the purpose of the
>> MTP):
>>
>> "If you want a Media Termination Point to implement features that
>> H.323 does not support (such as hold and transfer), check the check
>> box.
>>
>> Use this check box only for H.323 clients and H.323 devices that do
>> not support the H.245 Empty Capabilities Set message.
>>
>> If you check this check box to require an MTP and this device becomes
>> the endpoint of a video call, the call will be audio only."
>>
>>
>> Cheers,
>> Tom
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>
>