Plantronics Voyager 835 - Manual (Page 13)

9
Range
To maintain a connection, keep your headset within 33 feet (10 meters)
of the Bluetooth phone. If there are obstacles between your headset and
the phone you may experience interference. For optimal performance,
place your headset and phone on the same side of your body.
Audio quality degrades as you move out of range. When you are
far enough away to lose the connection, you hear a high tone in the
headset.
The headset attempts to reconnect for 60 seconds. If you move back in
range, you can manually reconnect by pressing the call control button.
note Audio quality is also dependent upon the device with which the
headset is paired.