Speed dial was a function available on many telephone systems allowing the user to place a call by pressing a reduced number of keys.
Most mobile phones used to have a contact list feature which provides similar abilities although most have an instant call button which only requires one click.
The capability for speed dial historically dates at least as far back as the Number One Electronic Switching System (1ESS) in 1965.
MOS memory chips were used to store phone numbers, which could then be used for speed dialing at the push of a button.
This was made possible by the low cost, low power requirements, small size and high reliability of MOS transistors, over 15,000 of which were contained on ten IC chips, including one chip for logic, one for the dial interface, and eight for memory.