Each bluetooth device has some number of services available for use by another device. In order to find services on the remote device you need to have Service Discovery Protocol (SDP) support in the Affix, which is enabled by default now. Services are located in hierarchical form.

To see available services on remote bluetooth device there are two commands browse and search. Some broken hardware or wrong implementation of Bluetooth stack (like in MS Windows) do not support browse. Search command tries to find all known services instead. For more info see reference page.

Output of browse command for mobile phone Nokia 7650 is shown below.

niko@niko:~$ btctl browse 1
Connecting to host 00:02:ee:46:22:39 ...
==============================
Service Name: Fax
------------------------------
SvcRecHdl: 0x10000
Service Class ID List: 
  "Fax" (0x1111)
  "Generic Telephony" (0x1204)
Protocol Descriptor List: 
  "L2CAP" (0x0100)
  "RFCOMM" (0x0003)
    Port/Channel: 1
Profile Descriptor List: 
  "Fax" (0x1111)
    Version: 0x0100
Browse Group List: 
  "PublicBrowseGroup" (0x1002)
==============================
Service Name: Dial-up Networking
------------------------------
 ... skipped
==============================
Service Name: Bluetooth Serial Port
------------------------------
 ... skipped
==============================
Service Name: OBEX Object Push
------------------------------
 ... skipped
==============================
Service Name: OBEX File Transfer
------------------------------
 ... skipped
    

Note that several devices (like Nokia 6210) require to add pincode to be browsable. Most of devices allow you to browse without pincode.