dialer

A dialer is a device or person that initiates a telephone call. In the context of a telephone instrument, the dialer's function is to input the number of the party the user wishes to contact. The signals generated by the dialer then activate switches in the local telephone office, establishing a connection to the called party.12

There are two main types of dialers:

• Rotary Dialers: Invented in the 1890s, these dials are rotated against spring tension and then released. Their return motion creates electrical pulses that signal the desired number to the switching office.2
• Push-Button Dialers: Introduced in the 1960s, these use a dual-tone multifrequency (DTMF) system. Pressing a button generates a unique combination of low and high-frequency tones, which are decoded at the switching office to identify the number. Push-button systems allow for more advanced functions, such as activating automated systems at the other end of the line.23