The Paxton Net2 Caller ID/GSM Access Control Reader allows you to open a door from anywhere using a mobile or landline phone as a credential — enabling access without a card. The last eight digits of the phone number are used as the credential in the access system without incurring any call charges. This is made possible through caller ID (CLID) technology. The GSM Reader can be used with an access controller for phone only, or can be combined with a proximity card reader so the user has an option of a local access card or their phone. The Caller ID/GSM reader means that you no longer need a credential or to be in front of the door to unlock it, so it is great for communal entrances, infrequently visited sites, car or truck vehicle gates, and even starting the air conditioner on the way into the office, to name a few.