An apparatus, provided in use in a first device comprises at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to: receive first information about a context provided by a controller, said first information being received from a base station; and cause the first device to transmit one or more ping messages to one or more second devices, said one or more ping messages comprising information about said context which causes one or more second devices to reply to the controller.