I'm curious about the McDonald's thing. Was the employee wearing it for work purposes, (running the drive-thru) or was it connected to her personal phone? I doubt very many businesses allow front line customer service people to use their personal phones with or without BT while working.

We had a guy who used to wear his office phone BT headset and his cell phone BT headset, one on each ear. He's somewhat like Dwight on the Office, and we were able to solve it via a team effort. Basically, we called him repeatedly on his cell number and called him a tool.