What is Automatic Call Distrubution?

It is a system which can assign calls to the most appropriate party, place callers on hold and let them wait until appropriate agent will become available. It maintains queues if call cannot be anwered immediately. Also it distributes load to agents according to desired rules. Most typical rule is that call will be assigned to the longest idle agent. This is the basic functionality. Most of the existing systems will provide lots of other features, like interflow, when if one of group of agents is overloaded, then ACD can assign calls to a backup group which could be cross-trained and not directly responcible for handling specific class of calls. Also there is a lot of entertaining features like music, waiting time updates and etc to keep people on the line.