[cisco-voip] MTP and transcoders with intercluster trunk

[Damian Turburville]

Hi,
Scenario as follows

CUCM 6.1 placing calls across a WAN link to another CUCM 6.1 but with firewalls in the way. As advised by other members of this fine forum I would need MTP's at either end to provide a fixed IP we can use on the firewalls for NAT.
We want to use G.729 across the WAN link to conserve bandwidth, I believe that since most IP phones (we use 7911, 7912, 7937, 7942 and 7960's) support G.729 natively that normally if a call is placed from IP phone to IP phone (even across a WAN link?) no transcoder will be required. Is this still the case if MTP's are involved? Or will transcoders be required?
Also as a related question, what variant of G.729 does CUCM 6.1 use? In the Region settings it is just down as G.729 but is this a high or medium complexity variant? This may be important to know in order to provision the right type of HW transcoders.

Many thanks,
Damian
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