A:Answer Call control depends on the phone itself, the headset simply sends and receives audio from your phone system. Most phones simply mute or hold the current line when answering an incoming call on a different line, but you will need to confirm how your phone handles different lines through your phone manufacturer.
Additionally, it's possible your phone supports wireless headset hookswitch control. If your phone supports this feature it might allow you to answer or end a current call by using the controls on your headset, but it won't allow you to transfer or answer other lines from the headset itself.