I have a client with a D160 that I put a "Call Park" on one button and "UnPark Call" on another button. To park a call while on a live call, you press the Call Park button. It then asks what park zone. Enter 1, 2, 3, etc and then ok/enter/done. That parks it that zone. To pickup, press the UnPark, enter the park zone 1,2, 3, etc and then ok/enter/done. Not 100% streamlined, but a little better.