Each Bluetooth enabled printer is identified by a unique Bluetooth Device Address (BDADDR). This address resembles a MAC address whereby the first three bytes are vendor, and the last three bytes are device (for example, 00:22:58:3C:B8:CB). This address is labeled on the back of the printer via a barcode for ease of pairing. To exchange data, two Bluetooth enabled devices must establish a connection. Bluetooth software is always running in the background, ready to respond to connection requests. One device (known as the client) must request/initiate a connection with another. The second device (the server) then accepts or rejects the connection. A Bluetooth enabled printer will normally act as a peripheral creating a miniature network with the host device sometimes referred to as a piconet. Discovery identifies Bluetooth devices that are available for pairing whereby the central device broadcasts a discovery request and devices respond. If a device is not discoverable, the central cannot pair unless in knows the BDADDR or has previously paired with the device.