Over 10 hours spend on this and really drive me crazy, any help is appreciate!
Tried with Android phone first:
Samsung NOTE2, Samsung Grand2, Samsung Glaxy S2 with android 2.2, android 4.2, androind 4.4 both with Original official NXT firmware, and latest LeJOS, If pairing from phone to NXT, the NXT would prompt window, just input the PIN same as in phone, but just quickly NXT returned to main menu, nothing more could see and still empty in Contracts list. otherwise, pairing from NXT to Phone, after Phone input the PIN, the NXT still say 'line is busy' or 'unsuccessful' in LeJOS, while the Phone state the NXT is paired successfully.
Tried with PC to NXT, both in WinXP and Win7, I even bought a standalone Bluetooth USB Key, similar, once Input the PIN in PC same as the one in NXT set, the NXT quickly to say 'Line is busy', then the PC always take couple minutes to finish the Driver installation seems like mapping to some COM Port, then PC state paired successfully, but it never did in NXT.
I googled a lot, no useful information can get. Any idea?
Finally I get it to work by replace the Bluetooth stack in my laptop, the experience proved the windows 7 stack can't suit, the one I used now is called bluesoleil, it also provide a management software, which I would say the UI really worried me at the beginning, it likes the very old days software, even more, it asking for license. with this bluesoleil, I also get my arduino bluetooth sensor paired to my laptop. I tried a generic stack provided by broadcom, but failed by it keep asking me to plug in the bluetooth adapter, and actually it's always there. So I have to give up the paring between NXT and android phone, the andorid phone don't support replace the bluetooth stack except refresh another ROM. Hope this information could help someone like me.