Contact controlled GSM phone caller, with free call controllable relay output, with temperature alarm and thermostat functions. Upon receiving input contact, provides alarm calls and text messages to a maximum of 4 phone numbers.
The output of the relay can be controlled from 4 phone numbers, with caller identification, at any time, plus from another 4 phone numbers on an occasional basis, up to an adjustable date. The dates for occasional control can be modified easily in a text message, thus an electronic key for AIRBNB can be provided and deleted. When set to operate without caller identification, an unlimited number of users can control the output relay.
The integrated thermometer of the unit can measure ambient temperature with an accuracy of ±2°C, which can be queried in a text message. Temperature alarm threshold values (lower, upper, or both) can be set, which trigger alarm calls, text messages, and even the output relay can be controlled like a thermostat, which resets after reaching the needed temperature.
In order to be connected to alarm systems, the unit has low power supply alarm below 11V, and automatic shutdown below 10.2V, for protecting the battery from deep discharge. For feedback of availability, heartbeat signalling can be set, and the SIM card will automatically forward balance info.

   Call and send SMS upon contact
   Temperature alarm with lower / upper threshold and relay control
   Gate control with free call, and with permanent and adjustable temporary authority eg. Electronic key for AIRBNB flat
   Power supply monitoring, battery protection against deep discharge
   Forwarding of balance info in text message
   Sending heartbeat messages
User's manual
SS21-GSM leaflet
Configurator program (for v1.13.147 firmware version or above)   
Version: v2.11
Win 7
Win 8
Win 10
FTDI USB Driver   
Win 7
Win 8
Win 10
Structure2 inputs, 1 relay, 1 thermometer
InputsNO or NC contact
Relaymax. 60V/2A, contact independent, NO
Range of thermometer-20°C / +50°C
Thermometer accuracy±2°C
Cellular BandsGSM 900/1800MHz
SIM cardNano-SIM (4FF)
Power9-30V DC / 500mA min.
USB connectionUSB 2.0 mini-B