OnReceive BroadcastReceiver not fired when outgoing call is answered

Question

I want to detect the outgoing call when it is answered, I use a BroadcastReciever with the following code:

class OutgoingReceiver : BroadcastReceiver
{
    public override void OnReceive(Context context, Intent intent)
    {
    string number = intent.GetStringExtra(Intent.ExtraPhoneNumber);
    string stateStr = intent.Extras.GetString(TelephonyManager.ExtraState);

       if (stateStr!=null)
       {
           if (stateStr.Equals(TelephonyManager.ExtraStateOffhook))
           { }
           else if (stateStr.Equals(TelephonyManager.ExtraStateIdle))
           { }
        }
     }
}

and use with this code the following permissions:

   <uses-permission android:name="android.permission.READ_PHONE_STATE" />
   <uses-permission android:name="android.permission.PROCESS_OUTGOING_CALLS" />
   <uses-permission android:name="android.permission.READ_PRECISE_PHONE_STATE" />

And also with this receiver on AndroidManifest.xml

<receiver android:name="OutgoingBroadcastReceiver" android:enabled="true" android:exported="true">
        <intent-filter>
            <action android:name="android.intent.action.PHONE_STATE" />
        </intent-filter>
        <intent-filter>
            <action android:name="android.intent.action.NEW_OUTGOING_CALL" />
        </intent-filter>
        <intent-filter>
            <action android:name="android.intent.action.PHONE_STATE_CHANGED" />
        </intent-filter>
    </receiver>

But it is fired only when the outgoing call is start or end. Please, Help me!!