For control, the relay with normally closed and normally opened contacts connected to the input switched terminal blocks are used. As the unit is connected to 220V/50Hz main power source, the default voltage is supplied to the normally opened contacts. By GSM commands (SMSs, calls), every channel or all the channels together may be deactivated and reactivated or reset (deactivation for the time divisible by 60 seconds). Depending on the command format (acknowledged or not), the SMS command acknowledgment may be sent. By status request, the SMS enlisting the channels that are currently activated or deactivated and describing the transmitters status is sent.