event to identify Call Answering In Android

Hi i am developing call recording application. I want to know call answering event. For example if the user lift the call then i have to start recording. How to know whether he answer开发者_Go百科ed a call or not

http://peacemoon.wordpress.com/2009/08/06/android-listening-to-incomingoutgoing-phone-calls/

    case TelephonyManager.CALL_STATE_OFFHOOK:
    //CALL_STATE_OFFHOOK;
// do ur work here(after receiving call)
    break;

You need to create a BroadcastReceiver and listen for the TelephonyManager events. ACTION_PHONE_STATE_CHANGED is the one you should listen.