A helper to derive timezone from phone numbers using giggsey/libphonenumber-for-php

PhoneToTimezone.php

<?php

use libphonenumber\NumberParseException;
use libphonenumber\PhoneNumberToTimeZonesMapper;
use libphonenumber\PhoneNumberUtil;

if (!function_exists('phone_to_timezone')) {
    /**
     * Returns a timezone for a phone number. Note, multiple timezones are
     * possible for non-US regions. Only the first timezone is returned.
     * Returns 'Etc/Unknown' when the number is invalid/unparseable, 
     * or if the timezone is not found in the library's mapping.
     *
     * @param string $number
     * @param string $region
     * @return string
     */
    function phone_to_timezone($number, $region = 'US'): string
    {
        $phoneNumberUtil = PhoneNumberUtil::getInstance();

        try {
            $phoneNumber = $phoneNumberUtil->parse($number, $region);

            return PhoneNumberToTimeZonesMapper::getInstance()->getTimeZonesForNumber($phoneNumber)[0];
        } catch (NumberParseException $e) {
            return 'Etc/Unknown'; // Same return value for valid numbers with unknown timezones
        }
    }
}