Ringback number
Encyclopedia
Ringback number is a number used by many telephone company
linemen/technician
s to test whether or not a new telephone line
installation is working correctly and the phone number is routing
properly.
Typically a lineman tests the terminal equipment (telephone set) ringer by calling a "ringback telephone number" or ringback vertical service code
and then hanging up and waiting for the phone to ring. Often upon connection the ringback number plays a low frequency signal tone
into the line to indicate that it's working and ready, at which point the technician "flashes
" the line (hangs up very briefly) one or more times to select a ringback. A higher pitched signal tone then indicates ringback is engaged, and the technician
hangs up. The phone will then ring, answering only with a verification tone if picked up.
The verification tone is added so that telephone subscribers will not be able to easily use the ringback system as an "intercom," to call other extensions
of their own phone line by simply initiating a ringback test and waiting for the phone to stop ringing and converse when someone has answered the extension.
Some ringback numbers are very local or regional in scope, while others are state-/province- or area-code
-wide: there appears to be no consistent national system for them. Every telephone company, whether large or small, determines its own ringback numbers for each individual central office, which tends to perpetuate the current situation of a mess of overlapping and/or spotty areas of coverage.
Under the North American Numbering Plan
, most North American area codes reserve telephone numbers beginning with 958 and 959 for internal testing. Some companies also reserve 999 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 ringback number
(to test the ringer when installing telephone
sets) and a loop around
(which connects a call to another inbound call to the same or another test number). Ringback numbers may appear in the 958 exchange, but there is no requirement that they reside there.
Some large telephone companies have toll-free numbers 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 Bell Canada
) have been known to disable all payphone
calls to 958 or 959 test lines.
Narcotics trafficking and other criminal activity can utilize 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 United States
must be assigned a telephone number in order to make calls, some can ring or chirp if that number is called. Many Customer-owned coin-operated telephones (COCOT) 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 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 Automatic Number Announcement Circuit (ANAC)
service or a telephone with caller ID. TelCo owned payphone are generally on dedicated payphone lines which respond to special tones and Custom Local Area Signaling Services
codes such as *5055 for ringback.
Telephone company
A telephone company is a service provider of telecommunications services such as telephony and data communications access. Many were at one time nationalized or state-regulated monopolies...
linemen/technician
Technician
A technician is a worker in a field of technology who is proficient in the relevant skills and techniques, with a relatively practical understanding of the theoretical principles. Experienced technicians in a specific tool domain typically have intermediate understanding of theory and expert...
s to test whether or not a new telephone line
Telephone line
A telephone line or telephone circuit is a single-user circuit on a telephone communication system...
installation is working correctly and the phone number is routing
Routing
Routing is the process of selecting paths in a network along which to send network traffic. Routing is performed for many kinds of networks, including the telephone network , electronic data networks , and transportation networks...
properly.
Typically a lineman tests the terminal equipment (telephone set) ringer by calling a "ringback telephone number" or ringback vertical service code
Vertical service code
A vertical service code or VSC is a special code dialed prior to a telephone number that engages some type of special telephone service...
and then hanging up and waiting for the phone to ring. Often upon connection the ringback number plays a low frequency signal tone
Signal tone
A signal tone or signalling tone is a steady periodic sound used to indicate a condition, for example on a telephone line or as an audible warning....
into the line to indicate that it's working and ready, at which point the technician "flashes
Hook Flash
Hook flash or flash is a button on a telephone that simulates quickly hanging up then picking up again . This action can signal the telephone exchange to do something. A common use of hook flash is to switch to another incoming call with the call waiting service...
" the line (hangs up very briefly) one or more times to select a ringback. A higher pitched signal tone then indicates ringback is engaged, and the technician
Technician
A technician is a worker in a field of technology who is proficient in the relevant skills and techniques, with a relatively practical understanding of the theoretical principles. Experienced technicians in a specific tool domain typically have intermediate understanding of theory and expert...
hangs up. The phone will then ring, answering only with a verification tone if picked up.
The verification tone is added so that telephone subscribers will not be able to easily use the ringback system as an "intercom," to call other extensions
Extension (telephone)
An extension telephone is an additional telephone wired to the same telephone line as another. In middle 20th century telephone jargon, the first telephone on a line was a "Main Station" and subsequent ones "Extensions". Such extension phones allow making or receiving calls in different rooms,...
of their own phone line by simply initiating a ringback test and waiting for the phone to stop ringing and converse when someone has answered the extension.
Some ringback numbers are very local or regional in scope, while others are state-/province- or area-code
Telephone numbering plan
A telephone numbering plan is a type of numbering scheme used in telecommunications to allocate telephone numbers to subscribers and to route telephone calls in a telephone network. A closed numbering plan, such as found in North America, imposes a fixed total length to numbers...
-wide: there appears to be no consistent national system for them. Every telephone company, whether large or small, determines its own ringback numbers for each individual central office, which tends to perpetuate the current situation of a mess of overlapping and/or spotty areas of coverage.
Under the North American Numbering Plan
North American Numbering Plan
The North American Numbering Plan is an integrated telephone numbering plan administered by Neustar which encompasses 24 countries and territories, including the United States and its territories, Canada, Bermuda, and 16 nations of the Caribbean...
, most North American area codes reserve telephone numbers beginning with 958 and 959 for internal testing. Some companies also reserve 999 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 ringback number
Ringback number
Ringback number is a number used by many telephone company linemen/technicians to test whether or not a new telephone line installation is working correctly and the phone number is routing properly....
(to test the ringer when installing telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
sets) and a loop around
Loop around
A loop line or loop around is a telephone company test circuit. The circuit has two associated phone numbers. When one side of the loop is called , the caller receives a test tone of approximately 1000 Hz...
(which connects a call to another inbound call to the same or another test number). Ringback numbers may appear in the 958 exchange, but there is no requirement that they reside there.
Some large telephone companies have toll-free numbers 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 Bell Canada
Bell Canada
Bell Canada is a major Canadian telecommunications company. Including its subsidiaries such as Bell Aliant, Northwestel, Télébec, and NorthernTel, it is the incumbent local exchange carrier for telephone and DSL Internet services in most of Canada east of Manitoba and in the northern territories,...
) have been known to disable all payphone
Payphone
A payphone or pay phone is a public telephone, often located in a phone booth or a privacy hood, with pre-payment by inserting money , a credit or debit card, or a telephone card....
calls to 958 or 959 test lines.
Narcotics trafficking and other criminal activity can utilize 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 United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
must be assigned a telephone number in order to make calls, some can ring or chirp if that number is called. Many Customer-owned coin-operated telephones (COCOT) 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 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 Automatic Number Announcement Circuit (ANAC)
Automatic number announcement circuit
An automatic number announcement circuit is a special telephone number that is meant to be used by phone company technicians and other telecommunications technicians to determine the phone number of a particular line....
service or a telephone with caller ID. TelCo owned payphone are generally on dedicated payphone lines which respond to special tones and Custom Local Area Signaling Services
Vertical service code
A vertical service code or VSC is a special code dialed prior to a telephone number that engages some type of special telephone service...
codes such as *5055 for ringback.
Ringback numbers
Vertical service codeVertical service codeA vertical service code or VSC is a special code dialed prior to a telephone number that engages some type of special telephone service...
*5505 ringback
305-780-6095 Ringback for Miami, Florida
320-XXX-XXXX Ringback for Montreal, Quebec.
507-XXX-XXXX Ringback for Alberta.
590-XXX-XXXX Ringback for (204) NPA.
777-XXX-XXXX Ringback for Indiana.
847-765-1008 Ringback for Chicago area codes.
954-780-6321 Ringback for (954) NPA.
954-999-XXXX Ringback for (954) NPA.
999-XXX-XXXX Ringback for (519) NPA.
999-XXX-XXXX Ringback for North Bay, Ontario (705)
999-XXX-XXXX Ringback for Ottawa, Ontario (613)
999-XXX-XXXX Ringback for portions of Toronto, Ontario (416)
970-99X-XXXX Ringback for Greeley, CO main exchange (970)