I'm not sure that checking the LAP code is going to work for trying to find N900. There is this list thelist (http://802.15ninja.net/bnapbnap/thelist.php) but it does not help much.

You could trying using SDP to check for the Bluetooth profile you want.
You could try this tool for checking the N900 SDP database.
ViewSDP (http://store.ovi.com/content/24022)