Hi all, I recall there having been some issues back in CUCM 4.x with SIP Trunks not supporting G.729 when requiring RFC 2833 for DTMF. Does anyone know exactly what the requirements are with CUCM 8 for SIP Trunking with G.729 if RFC 2833 DTMF is required? Hardware MTP required? DSPs required? etc.
You don't need DSPs for this; you can use an IOS software MTP for this, which just uses CPU cycles on the router. Just make sure the IOS SW MTP is in it's own unique MRG, and that is at the top of the MRGL for the SIP trunk.
You shouldn't need to check 'MTP required' on the trunk, either. CUCM will invoke the MTP if it needs it, depending on what the capabilities of the non-SIP trunk device is.