Mahesh,
I would say that this should work, but we have not tested that exact model. Other partners have configured door buzzer systems which were connected directly to the UC500. Some use and FXS port, others use an FXO port. With it connected to an FXO port, you should be able to "plar" the port to a blast group which would ring all the phones that you would like. Then once the connection is open to the door, the 85 key combination should open the door.
Thank you,
Darren