Dialing

Dialing is the process of initiating a telephone call by selecting a number or contact on a telecommunication device. Historically, dialing began with rotary dial telephones in the late 19th century, where the user turned a numbered wheel and released it to send a sequence of electrical pulses corresponding to the digits dialed. This pulse-dialing method remained common into the mid-to-late 20th century. In the 1960s and 1970s, tone dialing using dual-tone multi-frequency signaling (DTMF) was introduced, allowing digits to be sent as tones when the keypad was pressed, which enabled faster and more reliable call setup and supported new features such as voicemail and automated menus. By the 1980s and 1990s, push-button phones became widespread, and digital switching networks supported both pulse and tone dialing where available. With mobile and VoIP systems, dialing today typically means entering a number or selecting a contact on a handset, computer, or appliance, after which the network completes the connection.

International dialing involves additional conventions, governed by ITU-T E.164. Callers use an international access code (or plus sign in newer devices), followed by a country code, area code (where applicable), and the local number. National dialing rules vary by country and may require a trunk prefix for domestic long-distance calls, or may permit an abbreviated dialing format such as short codes or local numbers, depending on local numbering plans. Modern devices also support speed dial, contact lists, and voice dialing.