Add PhoneStateListener

You have to create a receiver to catch phone calls.

To do this, add this in your in manifest.xml:

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

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

and create these classes:

import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;
import android.util.Log;
import android.webkit.WebView;

public class MyPhoneStateListener extends PhoneStateListener {

    public static Boolean phoneRinging = false;

    public void onCallStateChanged(int state, String incomingNumber) {

        switch (state) {
        case TelephonyManager.CALL_STATE_IDLE:
            Log.d("DEBUG", "IDLE");
            phoneRinging = false;
            break;
        case TelephonyManager.CALL_STATE_OFFHOOK:
            Log.d("DEBUG", "OFFHOOK");
            phoneRinging = false;
            break;
        case TelephonyManager.CALL_STATE_RINGING:
            Log.d("DEBUG", "RINGING");
            phoneRinging = true;

            break;
        }
    }

}

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;

public class ServiceReceiver extends BroadcastReceiver {
    TelephonyManager telephony;

    public void onReceive(Context context, Intent intent) {
        MyPhoneStateListener phoneListener = new MyPhoneStateListener();
        telephony = (TelephonyManager) context
                .getSystemService(Context.TELEPHONY_SERVICE);
        telephony.listen(phoneListener, PhoneStateListener.LISTEN_CALL_STATE);
    }

    public void onDestroy() {
        telephony.listen(null, PhoneStateListener.LISTEN_NONE);
    }

}