activity_main.xml

<RelativeLayout xmlns:androclass="http://schemas.android.com/apk/res/android"  
    xmlns:tools="http://schemas.android.com/tools"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:paddingBottom="@dimen/activity_vertical_margin"  
    android:paddingLeft="@dimen/activity_horizontal_margin"  
    android:paddingRight="@dimen/activity_horizontal_margin"  
    android:paddingTop="@dimen/activity_vertical_margin"  
    tools:context=".MainActivity" >  
  
    <TextView  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:text="@string/hello_world" />  
  
</RelativeLayout>

Activity class

package com.example.callstatebroadcastreceiver;  
  
import android.os.Bundle;  
import android.app.Activity;  
import android.view.Menu;  
  
public class MainActivity extends Activity {  
  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
    }  
  
  
    @Override  
    public boolean onCreateOptionsMenu(Menu menu) {  
        // Inflate the menu; this adds items to the action bar if it is present.  
        getMenuInflater().inflate(R.menu.main, menu);  
        return true;  
    }  
      
}  

IncommingCallReceiver.java

package com.example.callstatebroadcastreceiver;  
  
import android.content.BroadcastReceiver;  
import android.content.Context;  
import android.content.Intent;  
import android.telephony.TelephonyManager;  
import android.widget.Toast;  
  
  
 public class IncommingCallReceiver extends BroadcastReceiver{  
      Context context;  
         
      @Override  
      public void onReceive(Context context, Intent intent){  
          try{  
           String state = intent.getStringExtra(TelephonyManager.EXTRA_STATE);  
  
              if(state.equals(TelephonyManager.EXTRA_STATE_RINGING)){  
                   Toast.makeText(context, "Phone Is Ringing", Toast.LENGTH_LONG).show();  
              }  
                
              if(state.equals(TelephonyManager.EXTRA_STATE_OFFHOOK)){  
                   Toast.makeText(context, "Call Recieved", Toast.LENGTH_LONG).show();  
              }  
                
              if (state.equals(TelephonyManager.EXTRA_STATE_IDLE)){  
                   Toast.makeText(context, "Phone Is Idle", Toast.LENGTH_LONG).show();  
              }  
          }  
          catch(Exception e){e.printStackTrace();}  
      }  
        
}