Gsm have now become the new norm for opening your Automatic gates or barriers The device is based on a mobile phone which uses a Sim card and is allocated it's own phone number there are two main types a dial to open and a Gsm intercom. Gsm's are a cheap way of operating your gates if there are going to be a large number of people using the automatic gates/Barrier as you don't have the cost of buying or replacement of remotes.The GSM intercom is perfect when your not always at home you never miss a visitor again and you don't need a cable from your house or Business to the gate so it will work as a reliable wireless intercom with no limit on distance . If you need help in choosing the right product or don't see what you need please contact us