Android play audio file during phone call

For my Android app, I want to play an audio file after answering the call from my application. App will initiate phone call and once receiver pick up the call, app should start playing recorded audio file.

By searching a lot in Google I found that this is not directly possible for unrooted device.

But any alternative of this or any other way to achieve this?

I want to implement this because functionality of the app is: if App user is in trouble, he can just press help button in the app and then app starts calling to the mentioned contact person and should play recorded audio file as soon as person received the call.