The central control unit - the communication server - is often housed in the main computer center while the access points/OpenScape 4000 SoftGates with the survivability unit is located in the computer center. The access points/OpenScape 4000 SoftGates are distributed on the campus and networked over a high-availability IP infrastructure. If the communication server in the main computer center is not available, the survivability unit takes over the entire system operation.

The survivability unit is indicated by the abbreviation CC-AP in all the following figures and on all operational user interfaces. This is based on the logic used for naming the control processors (CCA-SWU and ADP). Of course not only does the CC-AP run on the survivability unit, rather also - as in the host system - OpenScape 4000 Assistant and OpenScape 4000 CSTA.