Communications system with Centrex functionality has telecommunications system interface via which public and IP networks can be coupled to form virtual private network

摘要

The system has a first user group (12,22-24,28,32) for connection to a public network (40) and a second group (62,64) for connection to an IP-based network (50). At least one switching device (30) in the public network and at least one network transition point (70) have a telecommunications system interface (37;77) via which the public and IP networks can be coupled to connect both groups' users as a common group to form a virtual private network.