iPhone development - How to override microphone with contents of an audio file

Does anyone knows how to override the iPhone microphone with the content of an audio file?

Imagine a scenario where you are in a call and you wants to play some short audio to the other person hear it.

So, it would be necessary put the microphone (hardware) on hold, and write the content of the audio file into the mic buffer, using a delegate, after the audio finish the deleg开发者_开发技巧ate would return the normal state, where the mic write on its buffer.

Is it possible?

Thanks!

PS: I am not sure about what tags to put for this question, so if someone knows which frameworks would be necessary to be used, or any tag suggestion, let me know that I change the them.

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This isn't possible with the current SDK.

The best you can do is to get the user to put the phone into Speakerphone mode, then open your application and then play the sound at loud volume. The microphone would then pick it up.