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answer the phone at first ring with a built in modem which can be accessed by technicians to report conditions and program function parameters, one programmable function is the number of rings until the modem answers, another is whether to impose an additional charge for incoming calls or even accept
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as a signal for the installer to hangup the telephone. The exchange then places a reverting call to the originating line, causing the telephone to ring. When answered, the exchange plays a verification tone. The verification tone is issued so that telephone subscribers cannot easily use the ringback
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Most other numbers listed for ringback are specific to one exchange or one telco; available lists tend to be outdated and unreliable. Many former test numbers (such as 320 and 999 in Bell Canada territory) have been reclaimed for use as standard landline or mobile exchange prefixes, with the test
157:), a steady tone would then be heard (different then a regular dial tone). Hanging up the phone after this would result in a ring back. When the ring back was answered, the ring back process could be repeated by hanging up and lifting up the phone quickly again, and then hanging up.
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4101 was formerly valid on some mechanical switching systems to allow a call to the other party on a two-party line. Like 4104 (repair, long replaced by 611 in most cities), it was once a standard number in many areas but has disappeared as this equipment (and the
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for a telephone line that automatically calls the line that the call was placed from, after the caller has hung up. The typical use of this facility is by telephone company technicians for testing a new installation or for trouble-shooting.
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and other criminal activity can use payphones to conduct crimes anonymously, so many payphones are not equipped with a ringer at all, or a quiet "chirper" solid state speaker and designated "No
Incoming Calls". All payphones in the
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Ringback testing is an acceptance testing procedure conducted by telephone installers to verify the quality of customer premises wiring to prevent network damage from faulty equipment or installation. The test consists of calling a
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In the 1970s and early 1980s, 1199011 was a number that when called would result in another dial tone. Afterwards, if the phone was hung up and then quickly picked up again in less than approximately 1/2 second (ie: a
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Some ringback numbers are local or regional in scope, while others are larger in scope. Every telephone company determines its own ringback numbers for each individual central office. Under the
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set up for ringback. In most cases, these numbers remain undisclosed to prevent abuse. Some companies change their ringback number every month to maintain secrecy. Some carriers (such as
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for test exchanges. Numbers within these test exchange block ranges are used for various types of local and long-distance testing; generally, this block includes a
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no incoming calls at all. Where a payphone does not have any number listed on the unit, the number can be discovered from that phone by calling an
82:(ANAC) service or a telephone with caller ID. TelCo owned payphones are generally on dedicated payphone lines which respond to special tones and
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122:(which connects a call to another inbound call to the same or another test number). Ringback numbers may appear in the
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must be assigned a telephone number in order to make calls, some can ring or chirp if that number is called. Many
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system as an intercom between multiple stations in a residence on the same line by taking the stations off-hook.
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with a standard telephone. Upon answering the call, the exchange plays a unique
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Ringback numbers are typically not listed or communicated to subscribers.
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exchange, but there is no requirement that they reside there.
194:. Petersen, Julie K. (2nd ed.). Boca Raton, Fla.:
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Telecommunication facility for telephone line testing
106:for internal testing. Some companies also reserve
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75:customer-owned coin-operated telephones (COCOT)
241:(139), (19 July 1985). Seen 03 February 2021.
192:The telecommunications illustrated dictionary
161:codes moved (usually) to the 958 exchange.
149:service itself) has been decommissioned.
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80:automatic number announcement circuit
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129:Some large telephone companies have
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86:codes such as *5055 for ringback.
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190:Petersen, Julie (2002).
66:Narcotics trafficking
47:vertical service code
41:telephone number (
258:Telephone numbers
171:Plant test number
131:toll-free numbers
39:reverting calling
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234:Federal Register
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135:Bell Canada
120:loop around
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177:References
155:hook flash
147:party line
196:CRC Press
116:telephone
32:Operation
252:Category
214:51169186
165:See also
139:payphone
90:Examples
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23:is a
210:OCLC
200:ISBN
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19:A
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