It signals one of its 4 inputs being changed by sending an SMS with a specific user-definable message and/or dialling pre-programmed phone numbers. The two switchable outputs can be remotely controlled by SMS commands/toll-free dialling-in as standard, and with the optional DTMF decoder unit fitted, DTMF tones can also be used. With the optional RF module fitted, up to 4 remote controls such as panic wrist buttons can be enrolled to the GD-04 to trigger SMS transmissions or phone number dialling.

The two switchable outputs can be wirelessly extended to remote relays by enrolling the GD-04 optional RF module to UC-82 or AC-82 relay receiver units.

In addition, various Jablotron detectors can be enrolled to the RF module to enable SMS transmissions/dialling to be carried out in response to detector triggering for security applications.

Up to two TP-8x series wireless thermostats can be enrolled to the GD-04 via the optional RF module to facilitate heating system remote control and sensing. In addition to this a further two can be enrolled for remote sensing only. The heating system(s) can be remotely enabled/disabled by SMS, and low/high temperature (frost/fire) alerts can be passed to the user via SMS. Another clever feature is that the current temperature(s) as measured by the thermostat(s) can be supplied to the user in SMS form as part of the response to a STATUS interrogation by SMS.

Typical examples of applications include heating remote control, access system remote control, industrial applications and home appliance remote control.