In this case, an existing telecommunication system is operated as a sub-telecommunication system on Swyx, for example. Swyx manages the access to the public telephone network as well as to other networks. The sub-PBX is connected via ISDN to Swyx. The ISDN cards provided for this must be operated in NT mode in this case.

See D.1 Swyx as the main telecommunication system.

In this case an existing telecommunication system is operated as master telecommunication system, for example. Swyx is connected to this as a sub-PBX. A prerequisite for this is the subsystem capability of the existing telecommunication system. The access to the public network is managed by the existing telecommunication system

See D.2 Connection of Swyx as Sub-telecommunication System on a Main Telecommunication System.

In this case Swyx is operated in addition to an existing telecommunications system. Both systems have access to the public telephone network and/or other networks.

See D.3 Swyx alongside another system with additional access to the public network.