I am running 12.4(15)XW and have a lab configuration like this:-
CUCMA <--> SIP <--> CUBE <--> SIP <--> CUCMB
CUCMB is representing a SIP SP.
When I place a G729 call from CUCMA to CUCMB this works fine as does a G711 call. However If I start a G711 call from CUCMA to CUCMB and then from CUCMA try to transfer this to a G729 phone on CUCMA the transfer will fail.
Is this because the CUBE cannot accept a midcall codec change?