Contrary to the general opinion that only a Bluetooth connection can be active -. That's not true.
On my Nokia 6881 (firmware V 6:09:00) is such as TomTom (navigation systems) active. Now comes a call, so I lead the talks with the Headset HBH-610a. The navigation system goes long "sleep". I want a call to the headset lead (with active navigation): no problem: select, talking, stop talking. TomTom restart.
In a tested Motorola headset only calls can be accepted.