/**
  *  This method is used to fetch all users from the default customer table to list
  * them in the SendinBlue PS plugin.
  */
 public static function getCustomers($phone_number = null)
 {
     $customer_data = get_users(array('role' => 'customer'));
     $address_mobilephone = array();
     foreach ($customer_data as $customer_detail) {
         $iso_code = SIB_Model_Country::get_prefix($customer_detail->billing_country);
         if (count($customer_detail) > 0) {
             $address_mobilephone[$customer_detail->ID] = array('firstname' => $customer_detail->billing_first_name, 'lastname' => $customer_detail->billing_last_name, 'phone_mobile' => $customer_detail->billing_phone, 'iso_code' => $iso_code);
         }
         if ($phone_number != null) {
             $number = self::checkMobileNumber($customer_detail->billing_phone, $iso_code);
             if ($phone_number == $number) {
                 return $address_mobilephone[$customer_detail->ID];
             }
         }
     }
     if ($phone_number != null) {
         return "false";
     }
     return $address_mobilephone;
 }