I was wondering if it was possible to use a Norstar Compact ICS as remote OPX's for an Option 11c PBX, if so do I still have to use the M7310 or can I go to the M2616's at the remote location and what is needed by way of connection back to the 11c to use all telephone ports on the ICS. My scenario is that a company moved out of a building in which we purchased and they left behind a Compact ICS, and I want to know if and what will be needed to use this unit. Any help would be greatly appreciated.