Abbreviated dialing

Abbreviated dialing is the use of a very short digit sequence to reach specific telephone numbers, such as those of public services.

Carriers refer to the shortened number sequences as abbreviated dialing codes (ADCs).

[4] Privileged group-number, system-number, and enhanced-number lists provide access to numbers that typically would be restricted.

For text messaging, the technical equivalent is a short code; however, these are rented by their private users rather than being universal and for public services.

The caller can be presented with any one of a variety of responses that an advertiser defines: a voice or IVR call, a text message, a video or audio clip, a mobile coupon, game or an application.

Callers are prompted to say a keyword or key-phrase, which corresponds to an advertiser (e.g., "Food For The Poor" causes a connection to that non-profit charity).

The designation for special use in the NANP prevents their use as area codes and central office prefixes, eliminating about 8 million telephone numbers from assignment.