The Simulated Facility Group System manages a plurality of IP Centrex Groups within a GR303 interface, where each IP Centrex Group is assigned to a unique Simulated Facility Group. A Centrex Feature Gateway interconnects the IP Centrex Access Facilities that serve each IP Centrex Group to a GR303 interface. The Simulated Facility Group System calculates the IP Centrex Access Facility bandwidth requirement of each IP Centrex call set up request, based on a Call Type Parameter received from the Centrex Feature Gateway. On a per call basis, the Simulated Facility Group System checks the available bandwidth on the IP Centrex Access Facility that serves the Centrex Group from which the call originated. The Simulated Facility Group System determines if the call set up request requires a timeslot on the GR303 interface to the central office switch. If a timeslot is required, the Simulated Facility Group System determines if a timeslot is available on the GR303 interface. In addition, the Simulated Facility Group System enables the completion of intra-IP Centrex Group intercom calls without the use of IP Centrex Access Facility bandwidth.