The speed dial on the telephone allows a person to call a specific telephone number with just the push of a button. Speed dialing has the advantage of users not having to remember long telephone numbers and enter the long telephone number into their phones. The speed dial button further eliminates cumbersome phonebook lookups. This is especially handy for frequently called numbers or to quickly dial in an emergency. The speed dial function may work differently depending on the telephone type and possibly by telephone system. The range of solutions spans from decentralized implementation on the device all the way to a central solution in a cloud-based telephone system.
If the speed dial function is implemented right on the device, it has a non-volatile memory for specific buttons. A telephone number can be stored to this memory. Depending on the phone, the speed dial buttons may be additional buttons or the regular numeric keys themselves. On modern smartphones the subscriber can typically be called by first touching the stored contact. This function is comparable to speed dial, since it also eliminates remembering and entering telephone numbers.
A telephone system allows the speed dial function to even be implemented for telephones without speed dial memory. In this case, a telephone number is assigned a so-called speed dial in the system, where it is permanently stored. Using the speed dial only requires entering a defined special button such as the # or * button followed by a short single-digit or multi-digit number. The telephone system recognizes the speed dial by the special button and matches the subsequent short number with the actual long telephone number stored in the system and dials the number for the telephone.