Playing an pre-recorded audio file to somebody over a call

I understand that even though the AudioMan开发者_如何学Pythonager.STREAM_VOICE_CALL is available in the SDK for android, it is not actually been used to play a pre-recorded audio file, or atleast that is what i have heard/seen on the internet. My Question is this, if this is truly the way it is, how is prankdial accomplishing this?

Many similar questions have been asked but they all seem really old, so i was wondering if anybody has gained any more insight about this.

My Question is this, if this is truly the way it is, how is prankdial accomplishing this?

It is impossible. Android applications do not have access to the in-call audio stream. AudioManager.STREAM_VOICE_CALL is for volume control.