The conversion of telephony to IP often involves purchasing a new PBX. Although modern PBX systems are state-of-the-art and offer all sorts of modern features, but you will not find a connection for the existing door phones anywhere?
Auerswald has the solution: With the TSA-a/b door phone adapter, door terminals with an older 4-core interface or a 2-core connection in accordance with FTZ 123 D 12-0, which perhaps cannot be easily replaced for structural reasons, can be connected to the analogue port of a modern, VoIP-enabled PBX.
The existing door terminal, from Siedle, Ritto, Grothe, Telekom or Auerswald for example, can be kept. The TSA-a/b was not only designed for Auerswald PBX systems, it is also suitable for use on all conventional PBXs with analogue subscriber ports.