A feature group, in North American telephone industry jargon, is most commonly used to designate various standard means of access by callers to competitive long-distance services.
They defined switching arrangements from local exchange carriers central offices to interexchange carriers.
These arrangements were described in an official tariff[specify] of the National Exchange Carrier Association, filed with the Federal Communications Commission (FCC).[when?]
While there are other feature groups for local access,[1] the four common feature groups exist for access from the local subscriber to competitive long-distance carriers: These Feature Group alternatives allowed the LEC's end users to make long-distance calls using the interexchange carrier's network, when non-stored program-controlled exchanges could not be modified to provide equal access.
By the mid 1990s, Equal Access features in exchange software had rendered Feature Group D universally available in modern landline exchanges; the others are either used for calling card applications or are obsolete.