ErlangB
Erlang B is a mathematical formula used primarily in teletraffic engineering to calculate the probability that a call will be blocked in a circuit-switched system because all circuits are occupied. It was developed by A.K. Erlang in the early 20th century to analyze telephone traffic and has since become a standard tool for capacity planning in telecommunications, telecommunications switches, and call centers.
The formula expresses the blocking probability as a function of offered traffic in Erlangs (a dimensionless
Erlang B assumes that blocked calls are cleared and not retried, and that call holding times are
In practice, engineers use Erlang B to estimate how many circuits are needed to keep the blocking