Tonsignalen

Tonsignalen, roughly translated as “the tone signal” in Swedish, is a term used in signaling and audio engineering to describe an audible, periodic waveform that conveys information or indicates status within a system. It is most often associated with telecommunication networks but also appears in audio testing and control environments.

In telecommunications, tone signals are generated by switching equipment and heard by users or detected by devices to indicate progress or status. Common examples include dial tone (system ready for dialing), ringback tone (caller hears progress while awaiting the called party), busy tone (the called party is engaged), and reorder or error tones. Some systems also use multi-frequency signaling, such as DTMF tones, where combinations of frequencies convey digits or control information. The exact frequencies and formats of tones vary by region and network.

Outside telephone networks, tone signals serve roles in testing and calibration as well as in alarm and alerting systems. Test tones, such as sine waves of specific frequencies or sweep tones, are used to measure frequency response and channel characteristics in audio equipment and transmission paths. In industrial or building automation, audible tone signals may indicate fault conditions, status changes, or manual control actions.

Standardization and variation: While the concept of a tone signal is widely used, specific sets of tones and their meanings are standardized differently by national regulatory bodies and international organizations (for example ITU-T recommendations in telephony). Due to regional differences and evolving digital signaling practices, tone definitions can vary between networks and devices.

See also: dial tone, ringback tone, busy tone, DTMF, dual-tone signaling, call progress tones.