I can't see why it wouldn't, as it has with past versions and I certainly don't know why they would take a step backwards and design 15 to not work. A lot can depend on the particular Bluetooth device you are using and what "extra" features you expect to be able to use. If the device works with you phone for "regular" calls, then it should work with 3CX.
You could install and test without any commitment, if that is what is holding you back from moving to V15.