My CUCM is SIP trunking to CME. DSP on a 2811 router sitting by the CUCM is used for g729 and g711 transcoding between phones under each system. Calls are connected correctly. But when phoneA in CUCM calls phoneB, the latter hears lots of noise. The phone display shows that PhoneA is using g729 and phoneB is using g711. The RxSize on A is 10ms, TxSize is 20ms.
Both RxSize and TxSize on B are 20ms.
When phoneB calls phoneA, both are using g729, so no DSP is required and no noise on either end.
Is this a faulty DSP?