materio-base-d7/sites/all/modules/contrib/form/phone/include/phone.ru.inc

<?php

/**
 * @file
 * CCK Field for Russian phone numbers.
 */

function phone_ru_metadata() {
  // These strings are translated using t() on output.
  return array(
    'error' => '"%value" is not a valid Russian phone number<br>Russian Phone numbers should .... ',
  );
}

/**
 * Verifies that $phonenumber is a valid ten-digit Russian phone number
 *
 * @param string $phonenumber
 * @return boolean Returns boolean FALSE if the phone number is not valid.
 */

function valid_ru_phone_number($phonenumber) {

  //$phonenumber = trim($phonenumber);

  // define regular expression
  $regex = "/
    \D*           # ignore non-digits
    [78]?         # an optional 78
    \D*           # optional separator
    \d{3,5}       # area code 3-5 digit
    \D*           # optional separator
    \d{1,3}       # 3-digit prefix
    \D*           # optional separator
    \d{2}         # 2-digit line number
    \D*           # optional separator
    \d{2}         # 2-digit line number
    \D*           # ignore trailing non-digits
    /x";
  // return true if valid, false otherwise
  return (bool) preg_match($regex, $phonenumber);
}

/**
 * Convert a valid Russian phone number into standard +7 (495) 567-53-09 or +7 (444xx) 67-53-09 or mobile 8 910 414-56-90 format
 *
 * @param $phonenumber must be a valid ten-digit number (with optional extension)
 *
 */
function format_ru_phone_number($phonenumber, $field = FALSE) {

  // define regular expression
  $regex = "/
    ^\D*          # ignore non-digits
    ([78])?       # an optional 78
    \D*           # optional separator
    (\d{3,5})  	  # area code 3-5 digit
    \D*           # optional separator
    (\d{1,3})  	  # capture 3-digit prefix
    \D*           # optional separator
    (\d{2})       # 2-digit line number
    \D*           # optional separator
    (\d{2})       # 2-digit line number
    \D*           # ignore trailing non-digits
  /x";

  // get digits of phone number
  preg_match($regex, $phonenumber, $matches);

  // construct ten-digit phone number
  $phonenumber = $matches[1] . ' (' . $matches[2] . ') ' . $matches[3] . ' - ' . $matches[4] . ' - ' . $matches[5];

  return $phonenumber;
}