CCrmFieldMulti::detectCountryByPhone

static function detectCountryByPhone(string $phoneNumber): string
{
	/** @var Main\PhoneNumber\Parser $parserInstance */
	$parserInstance = Main\PhoneNumber\Parser::getInstance();

	$defaultResult = $parserInstance->parse($phoneNumber);
	if ($defaultResult->hasPlus() && $defaultResult->isValid())
	{
		return $defaultResult->getCountry();
	}

	// add "+" and try again
	$country = $parserInstance->parse('+' . $phoneNumber)->getCountry();

	return $country ?? '';
}