A communication system, cache, computer readable medium and method for preventing a packet channel in the communication network to time out. The method includes sending data from a cache (18) to a user terminal (16d), wherein the cache (18) is located at an interface device (12a-c); determining that the data is sent to the user terminal (16d) from the cache (18) without passing a core network (14); and generating and sending a dummy message (20) through the core network (14) to a device (22) having an internet protocol, IP, address.