I have a Viking 2000A door phone with a c 1000b controller set in N/O position connected to trunk port 704 with a couple of digital sets that have a DT 704 key. When door phone is pressed it will ring 3 times at door phone before ringing once at stations in the group. How do I set this to ring without such a delay? My butt set will ring immediatly when connected to the controller.