i would get outgoing call duration a call, I thought to get when the persone to the other side answer my call, but with PhoneStateListener we can get the state of a call, bu
I think this is possible simply by spying on the call log. You can query the call log at the end of a call and the duration field will tell you what you want to know.
Here's a nice tutorial. Just add the field CallLog.Calls.DURATION to the array.
http://www.dcpagesapps.com/developer-resources/android/25-android-tutorial-call-logs
I hope this helps.
Emmanuel