Establishing telecommunications call paths between clustered switching entities

In a telecommunications switching system or cluster comprising a plurality of switching modules or switching systems, apparatus comprising:

• means for convening first output signals to second output signals, each said first output signal comprising a plurality of synchronous pulse code modulated (PCM) signals received from said switching modules or systems, each said first output signal for carrying a plurality of PCM channels, each said second output signal comprising a plurality of composite packets transmitted periodically, and each composite packet comprising bytes of a plurality of PCM channels of said first output signals, the PCM channels of each composite packet having a common means for converting third output signals into PCM signals as a destination;
• and
• means for switching each composite packet of said second output signals to one of a plurality of third output signals, each said third output signal for transmission to a means for converting a third output signal into PCM signals for transmission to ones of said plurality of switching modules or systems;
• wherein each of said second and said third output signals comprise Asynchronous Transfer Mode (ATM) signals and said plurality of periodically transmitted composite packets are a plurality of composite ATM cells;
• wherein said first output signals further comprise packetized data signals, and wherein said means for converting first output signals to second output signals further comprise means for converting said packetized data signals into variable bit rate (VBR) ATM cells of said second output signals.