BTAccess Platform Compatibility Chart
See Feature Comparisons among BTAccess packages
  Update 1/18/06 - we now have support for Widcomm v1.6 and later which requires Windows Mobile 5, .Net Compact Framework 2.0, and the Visual Studio 2005 development environment.  If you are using one of these newer devices, get the BTAccess Mobile evaluation kit which now includes the binaries required for WM5 support.
 		  

Platform Compatibility 
  Widcomm v1.2: 
iPAQ 36xx, 37xx, 38xx, 39xx and Bluetooth CF cards from Philips, Belkin, or Dell (Axim)		 Widcomm v1.3: 
iPAQ 545x		 Widcomm v1.4 and v1.5:
All later iPAQ models, Dell Axim, and other PDAs
BTAccess Mobile No No Yes
BTAccess54 Yes (limited) Yes No
BTAccess Classic Yes No No

As you can see from the table, the main thing you need to know is what version of the Widcomm Bluetooth stack your device is using.  Because each stack has slightly different interfaces we had to create 3 separate binary dlls to support them.

Note that the older "standard" features in the BTAccess54 library would technically still work on an older iPAQ (38xx, 39xx).  As long as you weren't depending on the disabled features like BtRadioOn(), or the new stack features like PAN.  So for example if all you want to do in your application is search for devices and do SPPConnect, and have it work on all iPAQs, you could get away with just using BTAccess54 everywhere.  

Note that BTAccess Mobile will ONLY work on PocketPC (Windows Mobile) devices.

Also note that you cannot however use BTAccess Classic on a 545x iPAQ.  It will not even load due to some missing DLLs which are no longer shipped on the iPAQ.

Click here to see a BTAccess54 Feature Comparison List.