This type of IPBS1 IP base station is physically similar to other base stations with internal aerials but only supports 4 simultaneous calls. Up to 5 Compact Base Station units can be included in a system. If used as the master base station, the whole system is limited to 5 base stations. Compact Base Station are only supported if all the other base stations are running firmware version 3.3.11 or later.

The DECT R4 Radio Base Stations are used with IP Office only. You can have up to five base stations per system. Each station connects directly to a LAN switch using Ethernet cabling. The DECT R4 Radio Base Stations can either be powered by Power-over-Ethernet or by using external power supplies that are available as accessories.

Each standard DECT R4 Radio Base Station can handle up to eight concurrent calls while each Compact Radio Base Station can handle up to 4 concurrent calls. A special protocol called on-air synchronization ensures that active calls are seamlessly handed over from one DECT R4 Radio Base Station to the next one if a user with an active call roams through a building.