Erlang C

The Erlang C calculations are used to refine telecommunications traffic loading by incorporating queuing aspects into traffic density calculations.


Erlang Includes:
Erlang basics     Erlang B     Erlang C    


The Erlang B looks at traffic loading in peak loading times and the Erlang C refines further elements of this by looking at queuing aspects.

The Erlang C model assumes that not all calls may be handled immediately and some calls are queued until they can be handled.

Erlang C

The Erlang C model is used by call centres to determine how many staff or call stations are needed, based on the number of calls per hour, the average duration of call and the length of time calls are left in the queue. The Erlang C figure is somewhat more difficult to determine because there are more interdependent variables. The Erlang C figure, is nevertheless very important to determine if a call centre is to be set up, as callers do not like being kept waiting interminably, as so often happens.

Erlang summary

The Erlang formulas and the concepts put forward by Erlang are still an essential part of telecommunications network planning these days. As a result, telecommunications engineers should have a good understanding of the Erlang and the associated formulae.

despite the widespread use of the Erlang concepts and formulae, it is necessary to remember that there are limitations to their use. It is necessary to remember that the Erlang formulas make assumptions. Erlang B assumes that callers who receive a busy tone will not immediately try again. Also Erlang C assumes that callers will not hold on indefinitely. It is also worth remembering that the Erlang formulas are based on statistics, and that to make these come true an infinite number of sources is required. However for most cases a total of ten sources gives an adequate number of sources to give sufficiently accurate results.

The Erlang is a particularly important element of telecommunications theory, and it is a cornerstone of many areas of telecommunications technology today. However one must be aware of its limitations and apply the findings of any work using Erlangs, the Erlang B and Erlang C formulas or functions with a certain amount of practical knowledge.

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