Erlang (unit)

Publisher

Wikipedia

URL

https://en.wikipedia.org/wiki/Erlang_(unit)

Published

unknown

Updated

unknown

Accessed

2026-09-25

HTTP status

200

License

CC BY-SA 4.0; CC BY-SA with attribution; still store short excerpts and locators only

Source notes citing this source

• The Erlang B blocking probability for offered traffic E erlangs on m circuits is (E^m/m!) divided by the sum of E^i/i! for i from 0 to m. It can be computed by the recursion B(E,0)=1 and B(E,j)=E*B(E,j-1)/(E*B(E,j-1)+j). field report in context
• The Erlang B formula holds for any holding-time distribution with a finite mean, even though it is usually derived assuming exponential holding times; Poisson arrivals are still assumed. field report in context
• The Erlang C probability that an arriving call must wait, for E erlangs on m agents, is (E^m/m!)(m/(m-E)) divided by [the sum of E^i/i! for i from 0 to m-1, plus (E^m/m!)(m/(m-E))]. field report in context
• Because the Erlang C formula contains m/(m-E), it only gives a meaningful result when there are more agents than offered erlangs. At 100 erlangs, as in NICE's example, a steady-state Erlang C answer needs more than 100 agents on the phones before shrinkage. inferred in context
• Wikipedia's Erlang (unit) article says that in high-loss systems, where heavy congestion produces re-entrant (retry) traffic, the Erlang formulas fail to predict the number of circuits needed. field report in context
• Offered traffic is the traffic that would be carried if every call attempt succeeded. Carried traffic is the average number of concurrent calls measured over a period; carried traffic is less than offered by the blocked portion. field report in context

Cite this source record

APA

WarmTransfer. (2026, September 25). Erlang (unit). WarmTransfer. https://warmtransfer.net/knowledge/sources/wikipedia-erlang-unit

BibTeX

@misc{warmtransfer-wikipedia-erlang-unit,
  title  = {Erlang (unit)},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/sources/wikipedia-erlang-unit},
  note   = {Wikipedia, accessed 2026-09-25}
}