A dial tone is the signal that a person hears on a landline telephone before dialing a phone number. It serves as an indication that the phone is connected and operational. Typically, the dial tone disappears once the first number is dialed. It’s important to note that cell phones, in most cases, do not have a dial tone.
The introduction of the dial tone became widespread as telephone systems transitioned to automation, starting around 1947. Before this, callers had to interact with a switchboard operator to connect with another party. The dial tone was implemented to reassure callers that their phones were functioning properly and connected before placing a call.
In situations where multiple phones share the same telephone line at home or in an office, the use of the dial tone helps avoid confusion. It lets users know that the phone is ready for use, and it disappears once the dialing process begins.
Aside from the dial tone, there are other common telephone tones, including the disconnect tone when the other party hangs up, the busy signal, and the loud tone when the receiver is off the hook. Special information tones, such as the three-beep tones used by the phone company before recorded messages explaining call issues, also exist.
The dial tone concept has been adapted for additional purposes, such as indicating voicemail or other calling features. For cell phones, the absence of a dial tone is the norm. However, there are specific instances, like in certain cell phone models designed for older generations, where a dial tone sound may be used when the phone is opened.