Method and arrangement for coupling message in central control device with decentralised communications devices

The invention describes a novel private branch exchange and the migration solution with respect to existing devices. Communication connections are established via a transport network, the control takes place in a centralized manner by means of a central control device, which is connected to the decentralized switching devices and the interface modules via a two-stage connection, a collection and distribution of the control messages being carried out in a decentralized manner and the control connection from the respective decentralized device to the central control being provided by an ATM network or an Ethernet connection.