losing control after navigating from the activity to internet through webview

I have an activity containing 4 buttons. Clicking each butto开发者_开发技巧n will navigate to particular sites(used webview). When I am on this activity, I wrote a code for call blocking and it works well. But, when I click on the button, it will go to that particular site, at this time that call blocking is not working since I am out of that activity. I want to block call through out my application, ie even it goes to the particular sites. Any help would be appreciated.

//Activity String url2="http://www.gmail.com";

wv2=(WebView)findViewById(R.id.w2); wv2.setWebViewClient(new HelloWebViewClient()); wv2.loadUrl((String)url2);

    private class HelloWebViewClient extends WebViewClient 
    {    
        @Override    
        public boolean shouldOverrideUrlLoading(WebView view, String url) 
        {        
            view.loadUrl(url); 
            return true;  
            }
        }