title: how to validate user phone number in CakePhp
body: <p>I have created a user registration form in CakePHP.
  My intention is if user provide the phone number then it should be numeric and unique.
  So I defined follwing rules:</p>
  
  <pre><code> 'phone_no_should_be_numeric'=&gt;array(
                                        'rule' =&gt; 'numeric',
                     'message'=&gt;'Phone number should be numeric'
                                  ),
  'Phone_no_should_be_unique'=&gt;array(
                                'rule' =&gt; 'isUnique',
                    'message'=&gt;'Phone number already exist'
              ),
  </code></pre>
  
  <p>But because of this rule it is forcing user to enter phone number. Which i don't want.
  My intention is if user provide the phone number then it should be unique and numeric.
  Can anyone suggest me what is the best way to tackle such issue.</p>
  
  <p>Thnx in advance,
  joe</p>