We have announced End-of-Support for this feature on Oct 31 st 2018. Please refer this forum post for details and other alternatives. https://pitstop.manageengine.com/portal/community/topic/end-of-support-for-modem-based-sms-and-appsms-notifications ...
Error trace in agent logs: 2016/09/20 00:22:49:235 InternetGetRequestEx : The request is updated with the internet option security flags. 2016/09/20 00:22:49:251 InternetGetRequestEx : Error in WinHttpSendRequest -> -2146892963 2016/09/20 ...