Small system: 1-10 base-stations, 50 handsets and 20 simultaneous calls. (DECT manager is also a DECT base and in this mode it supports 5 concurrent calls)
Medium system: 11-60 base-stations, 250 handsets and 60 simultaneous calls. (Due to capacity, DECT manager is only a manager. Switching between Medium and Small is costing you one additional device.)
Large system: Up to 240 base-stations, 800 handsets and 240 simultaneous calls. N870 in role integrator only is needed.
Enterprise system: Up to 6000 base-stations, 20000 handsets and 6000 simultaneous calls. Virtual Integrator is needed.