SmsManager::getDefaultSender

static function getDefaultSender()
{
	$region = BitrixMainApplication::getInstance()->getLicense()->getRegion();

	if ($region === 'ru')
	{
		return static::getSenderById(BitrixMessageServiceSenderSmsSmsRu::ID);
	}
	if ($region === 'by')
	{
		return static::getSenderById(BitrixMessageServiceSenderSmsSmsAssistentBy::ID);
	}

	return static::getSenders()[0];
}