PaymentSlipConfig::getSelectedSmsServiceId

public function getSelectedSmsServiceId(): ?string
{
	if (!Loader::includeModule('messageservice'))
	{
		return null;
	}

	$selectedServiceId = Option::get('salescenter', self::OPTION_SELECTED_SMS_SERVICE, null);
	if (empty($selectedServiceId) || !$this->isSmsServiceActive($selectedServiceId))
	{
		/** @var BaseConfigurable|null $firstRegisteredSender */
		$firstRegisteredSender = current(CrmManager::getInstance()->getUsableSmsSendersList());

		if ($firstRegisteredSender)
		{
			Option::set('salescenter', self::OPTION_SELECTED_SMS_SERVICE, $firstRegisteredSender['ID']);
			$selectedServiceId = $firstRegisteredSender['id'];
		}
	}

	return $selectedServiceId;
}