Speed Calling service allows telephone

Telephone

The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...

 subscribers to assign one or two digit speed calling codes, by dialing a change speed calling list access code, a feature code

Vertical service code

A vertical service code or VSC is a special code dialed prior to a telephone number that engages some type of special telephone service...

, and a new telephone number

Telephone number

A telephone number or phone number is a sequence of digits used to call from one telephone line to another in a public switched telephone network. When telephone numbers were invented, they were short — as few as one, two or three digits — and were given orally to a switchboard operator...

. Thereafter, the subscribers need only use the assigned speed code to reach the desired party rather than dial the long phone number. This service became commonplace in the 1970s with the spread of Stored Program Control exchange

Stored Program Control exchange

Stored Program Control exchange is the technical name used for telephone exchanges controlled by a computer program stored in the memory of the system. Early exchanges such as Strowger, panel, rotary, and crossbar switches were electromechanical and had no software control...

s capable of implementing the required databases.