I know I can dial a number with the system.openURL API.

Once the call is answered is it possible to play an MP3 message to the person answering?

Is it possible to solicit touch tone input from the person answering.

I.E. Call a numbers, play an mp3 and request a confirm they received the message by pressing 1 on the tone pad?

Not with Corona.

I don't even think what you are asking is even possible with the Native Object-C SDK. Sounds to me like this is a service for the phone system.

You could maybe possibly do it with VOIP. But that is not doable in Corona.

C.