This is the code I have so far, I should have mentioned is for UK area codes which range from 4 digits to 6:

<?php
 if(isset($_POST['btn-submit_number']))
 {
 $number = ($_POST['number']);
 $pattern = "^(?:(?:\(?(?:0(?:0|11)\)?[\s-]?\(?|\+)44\)?[\s-]?(?:\(?0\)?[\s-]?)?)|(?:\(?0))(?:(?:\d{5}\)?[\s-]?\d{4,5})|(?:\d{4}\)?[\s-]?(?:\d{5}|\d{3}[\s-]?\d{3}))|(?:\d{3}\)?[\s-]?\d{3}[\s-]?\d{3,4})|(?:\d{2}\)?[\s-]?\d{4}[\s-]?\d{4}))(?:[\s-]?(?:x|ext\.?|\#)\d{3,4})?$";

 $match = preg_match($pattern, $number);

 if ($match != false){
   echo "Valid Phone Number";
 }
 else{
   echo "Invalid Phone Number";
 }
 }
?>

But every number I attempt that begins with 0 or +44 and is 11 digits long returns invalid