Save custom user meta on registration

You have to trigger the following hooks:

• user_register
• personal_options_update

• edit_user_profile_update

  add_action('user_register', 'addMyCustomMeta');    
  add_action('personal_options_update', 'addMyCustomMeta' );    
  add_action('edit_user_profile_update','addMyCustomMeta' );    
  function addMyCustomMeta( $user_id ) {    
             update_user_meta( $user_id, 'user_phone', $_POST['user_phone'] ); 
  }
  

Hope that helps!!