WM6.5 build 23016
WM 6.5 build 23085
However recently I came across a post that mentioned how to fix this problem courtesy Hdubli. It requires to make he following registry change.
If you don't know how to do this, I would recommend you go to the following post and download the registry editor
http://p320.blogspot.com/2009/02/mobile-registry-editor-for-asus.html
Once you have the registry editor, carry out an active sync with your device and run the registry editor. You should be able to see the following screen.
Navigate to the following key
HKEY_LOCAL_MACHINE --> Software --> Microsoft --> Obex
Right click the screen and say new String Value
Enter the Value Name protocols and Value Data as bth,irda
Say ok, and you need to restart your device, bluetooth should now be working !
Hope this helps, do drop me a comment, would love to hear from you, if your feeling generous you could donate a dollar :)
The main article on this phone is located here ..
http://p320.blogspot.com/2008/11/asus-p320-how-what-where.html