Detecting outgoing call and call hangup event in android

You should create a BroadcastReceiver:

public class CallReciever extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {

        if (intent.getStringExtra(TelephonyManager.EXTRA_STATE).equals(
                TelephonyManager.EXTRA_STATE_RINGING)) {

                // Phone number 
                String incomingNumber = intent.getStringExtra(TelephonyManager.EXTRA_INCOMING_NUMBER);

                // Ringing state
                // This code will execute when the phone has an incoming call
        } else if (intent.getStringExtra(TelephonyManager.EXTRA_STATE).equals(
                TelephonyManager.EXTRA_STATE_IDLE)
                || intent.getStringExtra(TelephonyManager.EXTRA_STATE).equals(
                        TelephonyManager.EXTRA_STATE_OFFHOOK)) {

            // This code will execute when the call is answered or disconnected
        }

    }
}

You should register you application to listen to these intents in the manifest:

<receiver android:name=".CallReciever" >
            <intent-filter>
                <action android:name="android.intent.action.PHONE_STATE" />
            </intent-filter>
 </receiver>