Desktop App: Bluetooth headset not connecting

Several different types of bluetooth headsets will not answer or end a call with RingCentral Win 7.5.2. I have tried on several different Win7 laptops. The headsets are high-end - Jabra, Creative, and Klipsch. On each machine the bluetooth connection was established, Win7 reports all BT headset, handsfree etc services running properly. All BT headsets worked properly in audio sink mode with iTunes . The headsets, with 7.5.2, cannot answer or end a call, although my voice carried thru the headset mic to the caller. I could NOT hear the caller. I tried with audio settings pointing directly to the correct device and then with them pointing to 'Same as system' (which was pointing to same device). HELP! I was told that RingCentral supports bluetooth headsets before I committed. In this day and age you would expect RingCentral to work with MOST BTs, not the just the few that are listed. I prefer to believe there is just a setting or version wrong somewhere because otherwise it's a show stopper for what has been an excellent solution to date. Thanks for any info you can provide.