A linked numbering scheme (LNS) is a dialing procedure in effect in a service area within which call routing between adjacent exchanges does not require a dialing code.
[citation needed] The term is only used in the United Kingdom, but not in the North American Numbering Plan.
Within the area, several million subscribers can call each other by dialing a uniform code.
For example, anyone calling from an (020) number can reach Transport for London travel enquiries by dialing 7222 1234.
This may mean that no standard numbers are reachable without dialling an area code in some localities.