diff --git a/src/main/java/ru/touchin/roboswag/components/telephony/IsCallingObserver.java b/src/main/java/ru/touchin/roboswag/components/telephony/IsCallingObserver.java
index 6608a5f..a393c18 100644
--- a/src/main/java/ru/touchin/roboswag/components/telephony/IsCallingObserver.java
+++ b/src/main/java/ru/touchin/roboswag/components/telephony/IsCallingObserver.java
@@ -23,10 +23,10 @@ import android.Manifest;
 import android.content.Context;
 import android.support.annotation.NonNull;
 import android.support.annotation.RequiresPermission;
-import android.telephony.PhoneStateListener;
 import android.telephony.TelephonyManager;
 
 import rx.Observable;
+import rx.Subscriber;
 
 /**
  * Created by Gavriil Sitnikov on 02/11/2015.
@@ -44,13 +44,7 @@ public final class IsCallingObserver {
         isCallingObservable = Observable
                 .<Boolean>create(subscriber -> {
                     final TelephonyManager phoneStateManager = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
-                    phoneStateManager.listen(new PhoneStateListener() {
-                        @Override
-                        public void onCallStateChanged(final int state, final String incomingNumber) {
-                            super.onCallStateChanged(state, incomingNumber);
-                            subscriber.onNext(isCallingState(state));
-                        }
-                    }, PhoneStateListener.LISTEN_CALL_STATE);
+                    phoneStateManager.listen(new PhoneStateListener(subscriber), PhoneStateListener.LISTEN_CALL_STATE);
                     subscriber.onNext(isCallingState(phoneStateManager.getCallState()));
                 })
                 .distinctUntilChanged()
@@ -64,4 +58,22 @@ public final class IsCallingObserver {
         return isCallingObservable;
     }
 
+    private static class PhoneStateListener extends android.telephony.PhoneStateListener {
+
+        @NonNull
+        private final Subscriber<? super Boolean> subscriber;
+
+        public PhoneStateListener(@NonNull final Subscriber<? super Boolean> subscriber) {
+            super();
+            this.subscriber = subscriber;
+        }
+
+        @Override
+        public void onCallStateChanged(final int state, final String incomingNumber) {
+            super.onCallStateChanged(state, incomingNumber);
+            subscriber.onNext(isCallingState(state));
+        }
+
+    }
+
 }