My bluetooth headset stops working when a call connects.

My Bluetooth headsets (all three) stop working when a call connects.

All other bluetooth functions work just fine - just not when a call connects.

I took the phone to the Genius bar last night. We wiped to factory rest, changed the handoff,etc. I was told that my only option is to purchase a new phone.

The tech claimed that this was a hardware issue. However, I was using the phone without any issues last Friday night, then suddenly it stopped working.

The phone has never been subject to any trauma or mis-use. Always stored in Otterbox defender.

Is anyone else having the same issue?? I can't help but to think that this is a software issue. I had just updated to 9.2.1

Please help.

Thank you.