Modify User Registration Form using plugin

Hi All,

I want to add a phone field to user registration form while adding// editing a user. I am using register_form action api in my plugin but to my vain it is not working.
I searched through the forum and found couple of plugins but they are not compatible with the version i am using.
Is register_form deprecated from version 2.8.4 ?. Or is there any other way of using it.Solution and suggestion are welcomed.
my piece of code

add_action('register_form','add_new_field');
 function add_new_field()
{
$html = "<table><tr class='form-field'>
<th scope='row'><label for='phone'>Phone</label></th><td><input name='phone' type='text' id='phone'value=''/></td></tr></table>";
echo $html;
}

I referenced the
following link