This kit is a One user gsm system for one entrance, the call is made to a mobile or landline number of your choice , up to three numbers can be programmed so if the first number cant be reached it will divert to the next and so on. On answering the call the user can open the gate by pressing a button on the phones keypad if required. The dial to open gsm funtion is also available where up to 100 users can call the unit to open the gate or door where there numbers have being preprogrammed.There is a sim card in the unit so whilst it dosent cost anything to open the gate or door as the call is rejected straight away it will use some credit to make calls out to the usThe door station “myCom” uses GSM technology; therefore few elements and just a power supply are needed: this allows to have a complete and reliable communication system. The call is made by the Profilo door station by a conventional button module or by digital keypad and it’s transmitted to a fixed or mobile telephone number[such as your own mobile] properly. Several external stations are allowed and multiple lock openings are separately managed, for instance door and gate. Therefore it’s a substantial alternative for an audio wired installation even pretty large (without limits of distance amongst outside station and inside receiver) with no wiring at all.er.