The switching network (102), which contains switching matrices (104 - 110; 120, 122) arranged in several stages, is connected via common speech paths (204) with a group of interface devices (128), in which analog to digital and digital to analog conversion of the signals from and to the subscriber is carried out. Digital subscriber lines (130, 136, 138) are connected to the switching network 102 via a digital subscriber's apparatus (140). The translators which are present in the database (142) are used as usual to translate the digits keyed by the subscriber; however, they are also used for distributed control of the system, since they work with a single data connection path, which is only a speech path (204), between the interface device and the switching network. Since the interface units (128) control the establishment of connection paths to the switching network, the central processor which was previously required is omitted. This makes it possible to keep down the cost of testing when the program changes. IMAGE
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