scope:

This specification sets forth the requirements for the Integrated Communications Switching System (ICSS), which shall provide diverse communications capabilities to operators, who are usually air traffic controllers, working in various facilities. These communications can be divided generally into two categories: ground - ground communications (typically between air traffic controllers), and air - ground communications (between operators and pilots). ICSS capabilities may be required at Air Traffic Control Towers (ATCTs), Terminal Radar Controls (TRACONs), Flight Service Stations (FSSs), and similar facilities (such as off-shore air route traffic control centers).