The off-hook tone (also off-hook warning, howling tone, or howler tone) is a telephony signal for alerting a user that the telephone has been left off-hook without use for an extended period, effectively disabling the telephone line.
The off-hook tone in exchanges of the North American Numbering Plan consists of a superposition of tones with the frequencies 1400 Hz, 2060 Hz, 2450 Hz, and 2600 Hz, played at a cadence of 100 ms on and 100 ms off.[1] The signal is applied to the local loop by the switching system for permanent signal treatment to alert an end user (subscriber) of an off-hook condition of the telephone set, i.e. that the telephone handset should be placed on-hook.
Before playing the signal, a certain timeout has to elapse, and on some systems an intercept message is announced (e.g. "If you'd like to make a call, please hang up and try again. If you need help, hang up and then dial your operator. This is a recording.").
A single burst of off-hook tone is sometimes used to indicate to a party that the call is being transferred, notably at 1-800-BELL-SOUTH (800-235-5768).
Some central office switches in the United States, notably older GTD-5 EAX systems, utilize a single frequency tone, 480 Hz, known as High Tone for this purpose. In either case, the tone is substantially louder than any other signal transmitted over a copper POTS circuit; loud enough to be heard across a room from an unused off-hook telephone.
Howleredit
In the United Kingdom, a warbling signal sounding rather like an alarm siren is played at steadily increasing volume to a telephone left off-hook and unused on telephone lines provided by the BT Group and many PABX extensions. It is sometimes referred to as a howler.
In some cases it is composed of the DTMF tones * and # played alternately.
Telephone lines provided by NTL/Virgin Media tend to use the American-style tones, including a recorded message.
^Telcordia GR-506-CORE Issue 3 December 2011, Signaling for Analog Interfaces, Section 17.2.8 Receiver-Off-Hook (ROH) Tone
External linksedit
High Tone
Design schematic
January 01, 1970
hook, tone, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, january, 2008, . This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Off hook tone news newspapers books scholar JSTOR January 2008 Learn how and when to remove this message The off hook tone also off hook warning howling tone or howler tone is a telephony signal for alerting a user that the telephone has been left off hook without use for an extended period effectively disabling the telephone line Contents 1 North America 2 Howler 3 See also 4 References 5 External linksNorth America editThe off hook tone in exchanges of the North American Numbering Plan consists of a superposition of tones with the frequencies 1400 Hz 2060 Hz 2450 Hz and 2600 Hz played at a cadence of 100 ms on and 100 ms off 1 The signal is applied to the local loop by the switching system for permanent signal treatment to alert an end user subscriber of an off hook condition of the telephone set i e that the telephone handset should be placed on hook Before playing the signal a certain timeout has to elapse and on some systems an intercept message is announced e g If you d like to make a call please hang up and try again If you need help hang up and then dial your operator This is a recording A single burst of off hook tone is sometimes used to indicate to a party that the call is being transferred notably at 1 800 BELL SOUTH 800 235 5768 nbsp Example of a North American Off hook tone source source Listen to an off hook tone from North America Problems playing this file See media help nbsp High Tone source source Listen to an older 480Hz off hook tone Problems playing this file See media help Some central office switches in the United States notably older GTD 5 EAX systems utilize a single frequency tone 480 Hz known as High Tone for this purpose In either case the tone is substantially louder than any other signal transmitted over a copper POTS circuit loud enough to be heard across a room from an unused off hook telephone Howler editIn the United Kingdom a warbling signal sounding rather like an alarm siren is played at steadily increasing volume to a telephone left off hook and unused on telephone lines provided by the BT Group and many PABX extensions It is sometimes referred to as a howler In some cases it is composed of the DTMF tones and played alternately Telephone lines provided by NTL Virgin Media tend to use the American style tones including a recorded message See also edit nbsp Telephones portalReferences edit Telcordia GR 506 CORE Issue 3 December 2011 Signaling for Analog Interfaces Section 17 2 8 Receiver Off Hook ROH ToneExternal links editHigh Tone Design schematic Retrieved from https en wikipedia org w index php title Off hook tone amp oldid 1219760950, wikipedia, wiki, book, books, library,
