Telekommunikationssystem och foerfarande foer anordnande av en ISDN-vaexelanslutning

An ISDN telecommunication system and a method for implementing a private branch exchange interface. The system comprises an ISDN exchange (1), a primary rate interface (2), a PBX interface (3) and an ISDN PBX (4) provided with a multi-channelling device (6) for dividing the primary rate interface (2) into at least two PBX interfaces (3, 3'). In the invention, a B channel in the primary rate interface is converted into a D channel, which is used in the PBX interface (3, 3'). On the other hand, the information in the D channel of the primary rate interface (2) can be used and is distributed between the PBX interfaces (3, 3').