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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Signal tone | 1/1 | https://en.wikipedia.org/wiki/Signal_tone | reference | science, encyclopedia | 2026-05-05T11:53:37.284385+00:00 | kb-cron |
A signal tone or signalling tone is a steady or pulsating periodic signal typically in the frequency range of sound for indicating a condition, communication protocol state, or serve as an audible warning. It may be composed of multiple frequency components, or could be a pure tone. In telephone systems, signaling tones are used as call progress tones for in-band indications to subscribers or operators. Certain telephone switching systems used tones, in-band or out-of-band, for signaling on trunks. Typical well-known call progress tones are dial tone, ringing tone, busy tone, and the reorder tone. A loud stutter tone is used to alert subscribers of a handset left off-hook, effectively disabling the circuit for receiving calls. Telephone service subscribers may subscribe to services, such as call forwarding, which may indicate function by a stutter dial tone.
== See also == Musical tone Dual-tone multi-frequency signaling (DTMF) Signaling (telecommunications)
== References ==