I'm trying to get the phone to play sounds over a phone line, ie. play them to the person at the other end of the call. I'm using CMdaAudioRecorderUtility. The documentation gives me the impression that you should be able to just do

iRecorderUtility->SetAudioDeviceMode (CMdaAudioRecorderUtility::ETelephonyNonMixed);

("When playing, the audio sample data is played to the telephony uplink and is not mixed with the device speaker.") But it doesn't seem to matter what value I use (from TDeviceMode), I always get the same behaviour:

If there is no call in progress, the sound is played on the speaker.
If there is a call in progress, the sound is played on the earphone. No sound is heard on the other end of the call.

I also tried this with the Sound example program in Series60Ex, with the same results.