The GSM modem is a programmable device for switching on and off heating and cooling systems in order to maintain the temperature in the space within defined limits. It can be set to turn on / off heating or cooling by simply sending SMS message from your mobile phone. When the modem receives the message, it will send a return message to your mobile phone that it has performed the assigned function. In order to be able to use it, it is necessary to take a prepaid or postpaid card from some of our telecommunications operators. Its advantages are that it can be used in residential, commercial and industrial buildings where there is no internet.