Build Android app that can play an mp3 file directly to a phone call.

I need an android developer who knows how to stream audio content to a phone conversation. The usage case: I have a pre-recorded audio message I want to play for callers when I receive business calls. I need an app created that has 1 button, when pressed it will play a mp3 to the current call. app workflow: 1. I receive/or make call 2. I open app 3. app has a play button, when I press it, a pre-set mp3 file plays to the caller To be clear:I want the app to send the audio directly to the phone call, so the caller can hear it, without using the speakers. Does any service provider know how to do this? Two apps that have similar functionality: 1 [login to view URL] 2 [login to view URL] Here is a thread with one approach: [login to view URL] Due to low quality bids, please indicate in your bid that you know how to play an audio file to an ongoing call. Thanks