... , factories, nursing homes, clubs,etc. Wireless Calling System / Table Calling System / Hotel Service System:Main function:(1) The system is made up of one receiver, transmitters ... down transmitter (operated by 1 pc 12V 23A battery), HE Calling transmitter (optional), HB Infrared inductive alarm transmitter (optional), HY ... room, worker, sickbed, or other places you can use this calling system.