Main Page | See live article | Alphabetical index A dial tone is a telephony signal used to indicate that the telephone exchange is working and ready to accept a call. When automated telephone systems were first being deployed they noticed that customers were often confused by the apparent lack of response (before this, an operator would answer) and would often feel the phone was not working. To avoid this, exchange systems would play a small buzzing sound into the line instead. See also: dial This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.