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Extended Erlang B |
  
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Extended Erlang B |
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A derivation of Erlang's original work, the Extended Erlang B Traffic Model is an analytical model for calculating call blocking. It makes the following assumptions:
| • | Calls are presented randomly to a trunk group (Poisson arrivals). |
| • | Call times are fixed or are exponentially distributed. |
In common with Erlang B, Extended Erlang B analyses the relationship between three variables, and each of these variables is represented by a either an argument or result of an Erlang for Excel function. If two figures are known, the third figure can be calculated. The three variables are:
Additionally, the Extended Erlang B Traffic Model takes into account the extra traffic offered to a trunk group caused by retries; that is, calls that are immediately redialled because they were blocked. This is known as the Recall factor.
This traffic model is commonly applied in situations where no overflow facilities exist.
See also