How will I know whether bluetooth will work with my mobile phone?

Manufacture and sales of the yellow bluetooth device has been discontinued. This FAQ is kept for historical purpose.

If you have :

a Windows Mobile 5 or 6 device, then NO Problem, just use the Windows Mobile application!
a BlackBerry device, No Problem (except Z10), just use the BlackbBerry application (all BlackBerries running software 4.2.1 or newer are JSR-82 compliant so you could theoretically use the GS-911mobile version too - you should use the GS-911Verifier to test your BlackBerry's JSR-82 compliancy...). Please Note: the BlackBerry application does NOT run on the latest Z10 generation! Please see: Will it work on my BlackBerry?)
an iPhone/iPad, you require the GS-911wifi - see the related FAQ !
a Normal phone that runs Java applications and has bluetooth (like most typical Nokia, Sony Ericsson, Samsung etc.) - These must be JSR-82 compliant (not all are!) - you should check your phones compatibility with GS-911Verifier (read below)
an Android device. Use the Android application. See the related FAQ for known issues: Does it run on my Android?

To read more on the GS-911Verifier, please see the related FAQ "What does the GS911Verifier do?".