use CMdaAudioInputStream while call active-error -13

Hi all,

Does anyone know can CMdaAudioInputStream be used to record audio while there's an active call?

Coz I've tried this and it gave error -13

I want to use this to detect dtmf, that's why I may not use CMdaAudioRecorderUtility because it will be not real time

And, if CMdaAudioInputStream can't be used during a call, then do you know the solution? Mine is :
using CMdaAudioRecorderUtility, record per 1 second and analyze the data until it found a DTMF, but I think the reaction will be quite slow

Or, is anyone know how to detect dtmf in a call?


thanx in advanced