Switching mechanisms are techniques devised to send messages in many dinections at once and to ensure that these messages are received with a minimum of delay. In other words, if a bottleneck or queue occurs in message traffic, bypasses or alternate paths to the destination are provided by taking recourse to switching mechanisms.
If traffic between two exchanges is too heavy, an alternate path is chosen. These exchanges perform the switching function for the telephone system. Switching is carried out by computers in most cases. Computers also serve to concentrate (collect) messages for transmission over higher capacity lines. The lines used in the telephone network are wires, coaxial cables, microwave and satellite links.