I try to record and play audio in PCM16 mode using CMMFDevSound with sampling rate of either 8 kHz or 16 kHz. The request buffer size is 4096 bytes for both recording and playing for N95 and I have no problems with these devices. For Nokia 6120 classic, however the request buffer sizes for recording and playing are different (1600 and 4096 bytes respectively). The mismatch makes it difficult or even impossible to achieve full audio duplex using this method. Does anyone encounter and have a solution for this problem?