[cisco-voip] Ringback / DTMF Problems through CUBE/Gateway when Invoking Hardware MTP from CUCM

[Jose Mujica]

I'll try here first before opening a TAC case. Just wondering if someone can
help me with the following problem.


Problem:

PSTN user gets no ringback on calls when they are being transfered from
Unity to IP Phones. And also DTMF is not working when calling from Remote
Site through the PSTN.

Topology:

                     Remote Site
-------------------------------------------------------------  Central Site

PSTN ---- Provider ---- SIP ---- CUBE/GWY/MTP ----- H323 ----- WAN --- H323
--- CUCM 4.x ------ Unity


The problem happens when CUCM invokes a hardware MTP within the CUBE Router.
When that MTP gets invoke then PSTN user hears no ringback from transfer
calls from Unity. Instead of invoking a hardware MTP I tried to invoke a
XCODE on the CUBE but same problem. The entire codec in use is G711 so there
is no transcoding taking place. However when invoking a software MTP on the
CUCM then ringback works without any problem. The problem is that I would
like calls to remain on the remote site instead of going to central site for
CUCM MTP.

I changed Send H225 to use Annunciator and it works when invoking a software
MTP but it doesn't work when invoking a hardware MTP. Hardware MTP has
access to the CUCM Annunciators via MGRL.  Also when invoking a hardware MTP
on the CUBE for some reason DTMFs are not working when dialing out from the
remote site through the SIP Trunk. DTMFs for calls coming in from the PSTN
arriving at Unity are working fine. So it is a 1-way DTMF problem. Again
DTMFs are working fine on both directions when using software MTPs on the
CUCM side. So all my problems are related when invoking a hardware MTP for
the call and for me it is a must to use a hardware MTP in order to maintain
the entire voice stream at the remote site when using the PSTN in/out from
the remote site.


Any ideas?

Thanks in advanced,
Jose
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