Basic implementation of https://github.com/giggsey/libphonenumber-for-php or https://github.com/practo/libphonenumber-for-php within CakePHP Model for phone number validation.

UK Phone number lookup

<?php
/**
* Presumes you've installed Composer in the directory according to http://getcomposer.org/doc/01-basic-usage.md
*/
require_once(APP . 'Vendor' . DS. 'LibPhoneNumber' . DS . 'src' . DS . 'libphonenumber'. DS ."PhoneNumberUtil.php");
require_once(APP . 'Vendor' . DS. 'LibPhoneNumber' . DS . 'src' . DS . 'libphonenumber'. DS ."CountryCodeToRegionCodeMap.php");
require_once(APP . 'Vendor' . DS. 'LibPhoneNumber' . DS . 'src' . DS . 'libphonenumber'. DS ."PhoneNumber.php");
require_once(APP . 'Vendor' . DS. 'LibPhoneNumber' . DS . 'src' . DS . 'libphonenumber'. DS ."data" . DS . "PhoneNumberMetadata_GB.php");
require_once(APP . 'Vendor' . DS. 'LibPhoneNumber' . DS . 'src' . DS . 'libphonenumber'. DS ."PhoneMetadata.php");
require_once(APP . 'Vendor' . DS. 'LibPhoneNumber' . DS . 'src' . DS . 'libphonenumber'. DS ."PhoneNumberDesc.php");
require_once(APP . 'Vendor' . DS. 'LibPhoneNumber' . DS . 'src' . DS . 'libphonenumber'. DS ."NumberFormat.php");
require_once(APP . 'Vendor' . DS. 'LibPhoneNumber' . DS . 'src' . DS . 'libphonenumber'. DS ."Matcher.php");
require_once(APP . 'Vendor' . DS. 'LibPhoneNumber' . DS . 'src' . DS . 'libphonenumber'. DS ."CountryCodeSource.php");
require_once(APP . 'Vendor' . DS. 'LibPhoneNumber' . DS . 'src' . DS . 'libphonenumber'. DS ."PhoneNumberType.php");
require_once(APP . 'Vendor' . DS. 'LibPhoneNumber' . DS . 'src' . DS . 'libphonenumber'. DS ."PhoneNumberFormat.php");

public function validatePhoneNumber($phoneNumber) {
  $phoneUtil = \libphonenumber\PhoneNumberUtil::getInstance();
  try {
      $numberData = $phoneUtil->parse($phoneNumber, "GB");
      $isValid = $phoneUtil->isValidNumber($numberData);
      if ($isValid){
        /* Included to demo further possible functionality
        var_dump($numberData);
    	  echo $phoneUtil->format($numberData, \libphonenumber\PhoneNumberFormat::NATIONAL) . PHP_EOL;
  		  echo $phoneUtil->format($numberData, \libphonenumber\PhoneNumberFormat::INTERNATIONAL) . PHP_EOL;
  		  echo $phoneUtil->format($numberData, \libphonenumber\PhoneNumberFormat::E164) . PHP_EOL;
  		  echo $phoneUtil->formatOutOfCountryCallingNumber($numberData, "GB") . PHP_EOL;
        */
  	}else{
  		return false;
  	}
  } catch (NumberParseException $e) {
      echo $e;
  }