Cancel outgoing calls when ringing

Question

Hello android developers! Is it possible to cancel an outgoing call when it starts ringing? I want to develop a kickphone application.

With the BroadcastReceiver I get the "start" of an outgoing call. But I don't know when the phone (on the other site) starts ringing.

I know that android knows when the ringing starts. Because everytime he dials and the ringing begin you hear a specific tone.

Thanks in advance