Hi, | I need know why you did not implement listener for UDP on Background | mode(for devices)? | I'm iPhone developer and according your document, listen on background | mode is able only with TCP protocol. Because Apple only supports TCP sockets for VoIP background mode. https://developer.apple.com/library/ios/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/AdvancedAppTricks/AdvancedAppTricks.html#//apple_ref/doc/uid/TP40007072-CH7-SW12 "stream" sockets are "TCP". UDP is not supported by Apple. Regards, Sebastian.