how to redirect mobile user to mobile page

Question 1

Download this detectmobile.js and make this changes in your head tag

 <head>
                <script src="detectmobile.js"></script>
                <script>
                        try {
                                // This is the URL where mobile
                                detectmobile.defaultMobileURL = "http://m.testing.com";
                                detectmobile.process();
                        } catch(e) {
                                // Make sure that in the fault modes
                                // we do not interrupt execution of other Javascript code
                        }
                </script>
        </head>

Question 2

Instead of using jquery you can use simple javascript to detect it:

if( /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent) ) {
 window.location.replace("http://m.tesing.com");
 //or window.location = "http://m.tesing.com";
}

Or other technique with CSS

/* Smartphones ----------- */
@media only screen and (max-width: 760px) {
  #some-element { display: none; }
}

jQuery:

$( document ).ready(function() {        
    if( $('#some-element').css('display')=='none' {
        window.location.replace("http://m.tesing.com");
     //or window.location = "http://m.tesing.com";    
    }
 });

Question 3

Use this code for detecting mobile devices and then redirect it

    <script language="javascript">
      if( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) 
      {
        window.location = "http://m.domain.com";
      }
    </script>

The test() method has been used to test for a match in a string and if a match is found then a redirection takes place. Add this code at the top of the main index.php page.

Use this code on the mobile index.php to redirect back

    <script language="javascript">
      if( !/Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) 
      {
        window.location = "http://testing.com";
      }
    </script>

As for the m.testing.com you will have to create an sub-domain.