Example of a PHP function for normalizing locally formatted phone number formats to E.164 using thePHP port of Google's libphonenumber project: https://github.com/davideme/libphonenumber-for-PHP

sanitize_number.php

<?php
use com\google\i18n\phonenumbers\PhoneNumberUtil;
use com\google\i18n\phonenumbers\PhoneNumberFormat;
use com\google\i18n\phonenumbers\NumberParseException;

require_once 'libphonenumber-for-PHP/PhoneNumberUtil.php';

function sanitize_number ($phone_number, $iso_code) {
    $pn = PhoneNumberUtil::getInstance();
    try {
        $parsed_number = $pn->parseAndKeepRawInput($phone_number, $iso_code);
    } catch (NumberParseException $e) {
        return $e->getMessage();
    }
    $is_valid = $pn->isValidNumber($parsed_number);
    if ($is_valid == true){
        return $pn->format($parsed_number, PhoneNumberFormat::E164) . PHP_EOL;
    } else {
        return "Phone number is not valid.";
    }
}

$raw_phone_number = "080 1234 5678";
$iso_code = "JP";

echo sanitize_number($raw_phone_number, $iso_code);