How accurate are the Erlang models?
They are usually quite accurate and have been used throughout the industry for decades. But they do make certain assumptions about the nature of offered traffic which may not necessarily apply in your case. For example, they assume random (Poisson) arrivals. This is usually reasonable, but sudden peaks of calls resulting from a radio or television advertisement are not accurately modelled. In these circumstances, you should use the calculators with caution and common sense.
