Can I inject my own audio into a phone call on the iPhone?

Question

Is there any way for an iPhone application to inject audio into an ongoing phone call?

For example, I'd like to play a song stored on my phone during a phone call, so that the person on the other end can hear it. Not through the speakers though, rather as if the song is my voice.

Is there a way to do this?

Answer 1

No. Apps cannot send audio to the iOS built-in Phone app's audio input or mic due to the OS security sandbox plus the audio session configured by Apple's Phone app.

An app can use the mic for input to itself.

You might be able to use 2 iPhones, one playing audio for the other's mic input, but that would use the speaker of the first one.