The Erlang unit is a measure of communication traffic or trunk occupancy (from telephone parlance). 1 Erlang = 3600 call-seconds = full occupancy of a trunk for one hour. Telephone trunk traffic tables set out the number of trunks required to give a desired grade of service (GOS)(= number of calls delayed more than a specified number of seconds in the study hour) (or = number of calls abandoned after a specified number of seconds in the study hour), for calls of a given average trunk occupancy (Erlangs, or call-seconds) per call.
There are two "Erlang formulas" in general use: Erlang B (for delayed calls abandoned) and Erlang C (for delayed calls held) Erlang C is also known as Molina or Poisson
Both Erlang B and Erlang C formulas assume calls are (traffic is) offered to the trunk group completely randomly from an infinite population source. While this approximately true for large telephone systems, it is definitely not true for small systems and usually not for trunked radio systems (where it is often incorrectly applied). For small systems, with non-random traffic the Erlang formulas generally give overly-conservative results (i.e., call for too many trunks for the given traffic), but in fact the formulas are not useful for non-random traffic and modelling is the preferred method.
Rename page to "Erlang_(disambiguation)" ?
Since this is a disambig page, shouldn't it be named "Erlang_(disambiguation)"? I don't know how to do renames, so.. I added a Template:About tag to the unit and programming language pages, which would have to be changed if this page is renamed, unless renaming one page automatically changes links in all the others. Jimw338 (talk) 05:15, 14 December 2014 (UTC)
- Whether this page should be at Erlang (disambiguation) is a matter of answering the question: Is there a primary topic? Since the current structure has been in place for 13 years, consensus has to be reached before an admin can move the involved pages. You can request a multiple page move to move Erlang to Erlang (disambiguation) and move Erlang (programming language) to Erlang. Cheers LittleWink (talk) 13:18, 14 December 2014 (UTC)