The mobile device is termed the MS (Mobile Station) in GSM and the UE (User Equipment) in UMTS/LTE. The capabilities of the device are dependent on the manufacturer, but general features include support for a variety of radio technologies and frequencies, assisting in global roaming. Supported technologies include 3GPP technologies, as well as non-3GPP technologies such as WiFi, Bluetooth and NFC (Near Field Communication). Mobile devices are uniquely identified by their IMEI (International Mobile Equipment Identity), which is tracked by the EIR (Equipment Identity Register) in order to prevent stolen devices from accessing the network. On board the mobile will be a 3GPP SIM (Subscriber Identity Module) or USIM (Universal SIM), depending on the functionality of the device (particularly with respect to supported security algorithms). The SIM/USIM holds subscriber credentials associated with accessing services, such as the subscriber’s IMSI (International Mobile Subscriber Identity) and secret key.