How to add audio to iPhone conversation?

Question

iPhone

Is it possible to play sound from the application during a call? The interlocutor must hear it.

Answer 1

When you call, the application goes to sleep. Then no.
But once on my old 3G I caught a glitch - the player continued to play quietly against the background of the conversation that had begun, but only I heard the music. I don’t really understand how this is possible, since the player’s audio session should have been interrupted, and the Phone application should have taken the audio device into its own hands, but maybe the audio session of the Phone application was initialized incorrectly ...
I’m not a big expert in matters of sound on an iPhone (I wrote only one application for working with sound), so please do not kick much.