In software, you can set the extension to be voice announce all the time and the Auto Answer key becomes a MUTE button. If you set it to be under user control, then the Auto Answer button controls whether the call is ringing or voice announce. In our U.S. TA version it's under Extension PT Personal Settings page 2, Alternate Ring. (2.3)
It just saves a digit so you don't have to append a * to your intercom calls.
LkEErie