1. A system for the exchange of digital information packets, comprising: an exchange including a plurality of connectors for interfacing said exchange to a plurality of transmission media; a plurality of modular expandable units, each of said plurality of modular expandable units having at least one input source terminal, at least one output terminal, and a central processing unit between said at least one input and said at least one output terminals; and at least two transmission media; wherein said plurality of modular expandable units are connected to said exchange through said at least two transmission media to allow a first transfer of a user-selected amount and type of digital information from a first one of said plurality of modular expandable units to a second one of said plurality of modular expandable units, wherein said user-selected amount and type of digital information is selected by inputting commands via an input device to software within each of said plurality of modular expandable units which locates and requests the transfer of the digital information packet, and wherein said plurality of modular expandable units are connected to said exchange through said at least two transmission media to allow a second transfer of a user-selected amount and type of digital information from the second one of said plurality of modular expandable units to at least a third one of said plurality of modular expandable units, such that said first one of said plurality of modular expandable units transfers data to said second one of said plurality of modular expandable units over at least two transmission media simultaneously.