How can I play audio over an open phone conversation? I would like to be able to play an audio recording over an open phone conversation. I.e., while the phone is connected (an outgoing call) a prerecorded audio file is played over the open phone connection.  How can I do this?
No, the best that you would be able to accomplish is playing a sound through the speaker so the microphone can pick it up. There are no api's that can accomplish that.