# Limited availability

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Limited_availability
> Markdown URL: https://mediated.wiki/source/Limited_availability.md
> Source: https://en.wikipedia.org/wiki/Limited_availability
> Source revision: 1356074733
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

"Grading scheme" redirects here. For Wikipedia's grading scheme, see [Wikipedia:Version 1.0 Editorial Team/Assessment § Grades](https://en.wikipedia.org/wiki/Wikipedia:Version_1.0_Editorial_Team/Assessment#Grades).

This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these messages) This article may be too technical for most readers to understand. Please help improve it to make it understandable to non-experts, without removing the technical details. (September 2010) (Learn how and when to remove this message) This article includes a list of general references, but it lacks sufficient corresponding inline citations. Please help to improve this article by introducing more precise citations. (July 2014) (Learn how and when to remove this message) This article needs additional or more specific categories. Please help out by adding categories to it so that it can be listed with similar articles. (May 2026) (Learn how and when to remove this message)

When customers of a [public switched telephone network](/source/Public_switched_telephone_network) make [telephone calls](/source/Telephone_call), they utilize a [telecommunications network](/source/Telecommunications_network) called a [switched-circuit](/source/Circuit_switching) network. In a switched-circuit network, devices known as switches are used to connect the [calling party](/source/Calling_party) to the [called party](/source/Called_party). Each switch has a number of inlets and outlets, and by connecting a specific inlet to the correct outlet, each switch helps to complete an end-to-end circuit between users. This method is used in, for example graded multiple banks of selectors.[1]

In a modern [circuit-switched](/source/Circuit-switched) network, [switches](/source/Telephone_exchange) can connect any inlet to any outlet; this is known as *full availability.*

## References

- Kennedy I., Lost Call Theory, Lecture Notes, ELEN5007: Teletraffic Engineering, School of Electrical and Information Engineering, University of the Witwatersrand, 2005.

- Akimaru H., Kawashima K., Teletraffic: Theory and Applications, Springer-Verlag London, 2nd Ed., 1999, p 6.

- Farr R.E., Telecommunications Traffic, Tariffs and Costs: An Introduction For Managers, Peter Peregrinus, 1988, p 90.

## Notes

1. **[^](#cite_ref-1)** [Inherent Load Balancing](http://www3.alcatel-lucent.com/bstj/vol50-1971/articles/bstj50-1-135.pdf) Bell System Technical Journal, Jan 1970, pp 135-165

---
Adapted from the Wikipedia article [Limited availability](https://en.wikipedia.org/wiki/Limited_availability) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Limited_availability?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.