Abstract: A signalling switch for use in information protocol telephony is provided, which can initiate, sustain, and terminate a plurality of discrete voice and data calls simultaneously. A plurality of cards are mounted on a computer bus, where the first card is a single board computer whose function is to act as the operations and maintenance control card for the switch. A non-system card functions as a message transport controller card; and there is at least one further non-system card which functions as a master application controller card. Local bus communication among the non-system cards is provided by a local bus found on the message transport controller card. Telephone routing information protocol software is resident in the switch, and the switch communicates externally via Ethernet interfaces.