Since Bluetooth devices are mobile and form networks dynamically, they need a way of finding other nearby devices to connect to. This process is called the inquiry procedure in the Bluetooth Baseband Specification (Specification of the Bluetooth System, Version 1.1, Volume 1: Core, Part B: Baseband Specification). A discovered device is identified by its Bluetooth device address, as well as its class of device (CoD) value.
The CoD value indicates the capability of the device. The CoD field shows if a device has rendering capabilities, like a printer, or is an audio device, like a headset. Some numerical values are reserved by the Bluetooth specification.
A Bluetooth device can have various settings for its "discoverable mode." For example, a device may be configured to not be discoverable. In this case, other Bluetooth devices that are within range won’t detect it. Alternatively, a Bluetooth device may be configured to be generally discoverable by other Bluetooth devices. In this case, the discoverable mode will be set using the General Unlimited Inquiry Access Code (GIAC). A Bluetooth device may also be configured to be discoverable in a "limited" manner by other Bluetooth devices by using a limited inquiry. In this case, the discoverable mode is set using the Limited Dedicated Inquiry Access Code (LIAC).
Normally, an inquiry is done with the GIAC. But the Java™ and Symbian Bluetooth APIs also offer the possibility of using a LIAC.
Note: The S60 3rd Edition FP 1 implementation of the Bluetooth API does not support using LIAC because the Symbian Bluetooth stack does not support the operation. Also changing the discovery mode is not supported at all.