The Near Field Communications (NFC) standard, developed by Sony and Philips has already been incorporated by Nokia in their mobiles. The Nokia solution works over a few centimetres and can have two active, or one passive and one active devices communicating. The technology works in a similar way to RFID tags, except for the option of having two active devices.
Using the Wi-Fi, Bluetooth or GSM capabilities of a mobile would also allow data to be downloaded to the device for future use (such as next month’s bus pass, or tonight’s cinema tickets). Therefore the mobile would be able to provide access control just by being swiped at the door.