Asignal toneorsignalling toneis a steady or pulsatingperiodicsignal typically in the frequency range ofsoundfor indicating a condition,communication protocolstate, or serve as an audible warning. It may be composed of multiple frequency components, or could be apure tone.
In telephone systems, signaling tones are used ascall progress tonesforin-bandindications to subscribers or operators. Certain telephone switching systems used tones, in-band or out-of-band, forsignalingon trunks.
Typical well-known call progress tones aredial tone,ringing tone,busy tone,and thereorder tone.[1]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.
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editReferences
edit- ^V. S. Bagad and I. A. Dhotre (2009).Data Communication Systems.Technical Publications. p. 8.ISBN978-81-8431-698-8.
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