User accepted the call.
Answered by machine
Busy.
Calling.
Failed to cancel the call.
Canceled the call.
Canceling the call.
Call failed.
User hung up the call.
Phone rang but no one answered, a missed call
Service unavailable.
Ringing.
Call succeeded.
Timeout.
Dial out state.
Normal process: Calling-> Ringing->Accepted->Success
Busy process: Calling->Busy