Voyager 815/855: Answering and Ending Calls
The unit also has a retractable boom that doubles as an answer end feature. You can extend the boom to answer and retract to hang up as well. There are small tabs "grips" on the either side of the unit to help grip the cover.
You can use the call answer end button to answer the call then extend the boom without call interruption.
If the boom is retracted while on a call, the call will be disconnected from the headset but should still be on the phone.