Abstract: A virtual PBX capability is provided to a group of user packet stations served by a packet switching system. The system establishes a virtual circuit between each distinct pair of stations in the group. The stations exchange signaling packets via the virtual circuits and respond to such packets by coordinating the initiation and disconnection of voice, data, or image calls. All call processing, including the provision of features such as call forwarding and automatic callback, is accomplished by the stations without the aid of the switching system. A fraud prevention mechanism is included in the switching system to prevent unauthorized stations from communicating as part of the virtual PBX group.

Abstract: A switching system including a number of switching modules each having a plurality of access ports. Incoming and outgoing packet channels are extended between each switching module and an inter-module packet switch. Each switching module includes a packet switching unit that transmits user information packets, received from the access ports, via the incoming packet channel to the inter-module packet switch, and switches user information packets, received via the outgoing packet channel from the inter-module packet switch, to the access ports for inter-module packet-switched communication. The intermodule packet switch concurrently packet switches user information packets, received on a number of the incoming packet channels, via multiple independent paths to a number of the outgoing packet channels.