Problem with SetAudioDeviceMode

Hi All!

I try to answer for telephone call by playing wav-file to phone line on the Nokia 6680. This is my code:
in CallHandler.cpp

void CCallHandler::RunL()
{
....
case RCall::EStatusRinging:
{
iCall.AnswerIncomingCall();
break;
}
....
iNotify->IncomingCall(iDialedNumber);
}
in AppView.cpp
void IncomingCall(TName aCallName)
{
...
if (iRecorderAdapter)
{
iLabel->SetTextL(aCallName);
iRecorderAdapter->PlayL();
}
...
}
and in recorderadapter.cpp:

void CRecorderAdapter::PlayL()
{
// Play through the device speaker
/*iMdaAudioRecorderUtility->
SetAudioDeviceMode( CMdaAudioRecorderUtility::ETelephonyOrLocal );
*/
iMdaAudioRecorderUtility->
SetAudioDeviceMode( CMdaAudioRecorderUtility::ETelephonyNonMixed );

// Set maximum volume for playback
iMdaAudioRecorderUtility->SetVolume( iMdaAudioRecorderUtility->MaxVolume() );

// Set the playback position to the start of the file
iMdaAudioRecorderUtility->SetPosition( TTimeIntervalMicroSeconds( 0 ) );

iMdaAudioRecorderUtility->PlayL();
}

But it doesn't work. I tried to use different params in the method SetAudioDeviceMode but result is the same.

Where is a problem?