The term telecoms resilience means enabling a telephone subscriber to continue to be served even when one line is out of service. The UK carrier networks are required by Ofcom to be 99.999% resilient. This means there should be no more than 5 minutes per year downtime in any single telephone exchange.
Connectivity from the local telephone exchanges to the customer premises is called the "last mile". This can be an ISDN30 connection, delivered through either a copper or fibre cable. This ISDN30 can carry 30 simultaneous telephone calls and many direct dial-in telephone numbers, (DDI's).
When leaving the telephone exchange, the ISDN30 cable can be buried in the ground, usually in ducting, at very little depth. This makes any business telephone lines vulnerable to being dug up during streetworks, liable to flooding during heavy storms and general wear and tear due to natural elements. Loss, therefore, of the "last mile" will cause the failure to deliver any calls to the business affected. Business continuity planning often provides for this type of technical failure.
Any business with ISDN30 type of connectivity should provide for this failure within its business continuity planning. There are many ways to achieve this, as documented by both the Cabinet Office and the CPNI.
Dual parenting
Dual parenting is where the telephone carrier provides the same numbers from two different telephone exchanges. If the cable is damaged from one telephone exchange to the customer premises most of the calls can be delivered from the surviving route to the customer.
Diverse routing
Diverse routing is where the carrier provides more than one route to bring the ISDN 30’s from the exchange, or exchanges, (as in dual parenting), but they may share underground ducting and cabinets, (those green boxes by the side of the road.)
Separacy
Separacy is the carrier can provide more than one route to bring the ISDN 30’s from the exchange, or exchanges, (as in dual parenting), but they may not share underground ducting and cabinets, and therefore should be absolutely separate from the telephone exchange to the customer premises.
Exchange based solutions
Exchange based solutions are where a specialist company working in association with the carriers offers an enhancement to the ability to divert ISDN30’s upon failure to any other number or group of numbers. Carrier diversions are usually limited to all of the ISDN30 DDI numbers being delivered to 1 single number. In the UK, GemaTech offers this service in association with all of the carriers other than Verizon. By being in the exchanges, the GemaTech version offers a part diversion service if required and voice recording of calls if required.
Non-exchange based diversion services
Non-exchange based diversion services are where a specialist company working in association with BT offers an enhancement to the ability to divert ISDN30’s upon failure to any other number or group of numbers. Carrier diversions are usually limited to all of the ISDN30 DDI numbers being delivered to 1 single number. In the UK Teamphone offers this service in association with BT Group. By not being in the exchanges, the Teamphone version offers an all or nothing diversion service if required but does not offer voice recording of calls.
Ported number services
Ported number services are where customers numbers can be ported to a specialist company where the numbers are pointed to the ISDN30 DDI numbers during business as usual and delivered to alternative numbers during a business continuity need. These are generally carrier independent and there are a number of companies offering such solutions in the UK.
Hosted numbers
Hosted numbers are where the carriers or specialist companies can host the customers numbers within their own or the carriers networks and deliver calls over an IP network to the customers sites. When a diversion service is required, the calls can be pointed to alternative numbers.
Inbound numbers (08 type services)
Inbound numbers are where the carriers or specialist companies can offer 08/05/03 prefixed numbers to deliver to the ISDN30 DDI numbers and can point them to alternative numbers in the event of a diversion requirement. Both carriers and specialist companies offer this type of service in the UK.
Smartnumbers (both Geographic and Non-Geographic type services)
A smartnumber is a new type of voice continuity number where instead of storing the telephone number in the local BT telephone exchange, it is instead stored in BT's voice continuity 'cloud'. Calls made to a smartnumber can be delivered to any handset anywhere in the UK or the world, thus protecting a company from loss of a telephone exchange, loss of the ISDN or SIP circuits connecting the company to the telephone exchange, loss of the customers PBX on their premises or denial of access to their business premises. Should any of these circumstances occur, the company can use a web-based portal to change the call routing to individual numbers or to large groups of telephone numbers at the same time.
Digital Access Signalling System 2 (DASS2) is an obsolescent protocol defined by British Telecom for digital links to PSTN based on ISDN. Although still available on request, it has been superseded by ETS 300 102 ("EuroISDN").
Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Work on the standard began in 1980 at Bell Labs and was formally standardized in 1988 in the CCITT "Red Book". By the time the standard was released, newer networking system with much greater speeds were available, and ISDN saw relatively little uptake in the wider market. One estimate suggests ISDN use peaked at a worldwide total of 25 million subscribers at a time when 1.3 billion analog lines were in use. ISDN has largely been replaced with digital subscriber line (DSL) systems of much higher performance.
In telecommunications, a customer-premises equipment or customer-provided equipment (CPE) is any terminal and associated equipment located at a subscriber's premises and connected with a carrier's telecommunication circuit at the demarcation point ("demarc"). The demarc is a point established in a building or complex to separate customer equipment from the equipment located in either the distribution infrastructure or central office of the communications service provider.
Digital subscriber line is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly installed DSL technology, for Internet access.
A payphone is typically a coin-operated public telephone, often located in a telephone booth or in high-traffic outdoor areas, with pre-payment by inserting money or by billing a credit or debit card, or a telephone card. Prepaid calling cards also facilitate establishing a call by first calling the provided toll-free telephone number, entering the card account number and PIN, then the desired telephone number. An equipment usage fee may be charged as additional units, minutes or tariff fee to the collect/third-party, debit, credit, telephone or prepaid calling card when used at payphones. By agreement with the landlord, either the phone company pays rent for the location and keeps the revenue, or the landlord pays rent for the phone and shares the revenue.
Telephone slamming is an illegal telecommunications practice, in which a subscriber's telephone service is changed without their consent. Slamming became a more visible issue after the deregulation of the telecommunications industry in the mid-1980s, especially after several brutal price wars between the major telecommunications companies. The term slamming was coined by Mick Ahearn, who was a consumer marketing manager at AT&T in September 1987. The inspiration for the term came from the ease at which a competitor could switch a customer's service away from AT&T by falsely notifying a telephone company that an AT&T customer had elected to switch to their service. This process gave AT&T's competitors a "slam dunk" method for the unauthorized switching of a customer's long-distance service. The term slamming became an industry standard term for this practice.
A toll-free telephone number or freephone number is a telephone number that is billed for all arriving calls instead of incurring charges to the originating telephone subscriber. For the calling party, a call to a toll-free number from a landline is free of charge.
Call forwarding, or call diversion, is a telephony feature of some telephone switching systems which redirects a telephone call to another destination, which may be, for example, a mobile or another mobile or another telephone number where the desired called party is available. Call forwarding was invented by Ernest J. Bonanno. In North America, the forwarded line usually rings once to remind the customer using call forwarding that the call is being redirected. More consistently, the forwarded line indicates its condition by stutter dial tone. Call forwarding typically can redirect incoming calls to any other domestic telephone number, but the owner of the forwarded line must pay any toll charges for forwarded calls. Call forwarding is often enabled by dialing *72 followed by the telephone number to which calls should be forwarded. Once someone answers, call forwarding is in effect. If no one answers or the line is busy, the dialing sequence must be repeated to effect call forwarding. Call forwarding is disabled by dialing *73. This feature requires a subscription from the telephone company. Also available in some areas is Remote Access to call forwarding, which permit the control over call forwarding from telephones other than the subscriber's telephone. VOIP and cable telephone systems also often allow call forwarding to be set up and directed via their web portals.
In telecommunications, directory assistance or directory inquiries is a phone service used to find out a specific telephone number and/or address of a residence, business, or government entity.
The public switched telephone network (PSTN) provides infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telephony operators. These consist of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all interconnected by switching centers which allow most telephones to communicate with each other.
A leased line is a private telecommunications circuit between two or more locations provided according to a commercial contract. It is sometimes also known as a private circuit, and as a data line in the UK. Typically, leased lines are used by businesses to connect geographically distant offices.
A business telephone system is a multiline telephone system typically used in business environments, encompassing systems ranging in technology from the key telephone system (KTS) to the private branch exchange (PBX).
KCOM Group is a UK communications and IT services provider. Its headquarters are in the city of Kingston upon Hull, a unitary authority in the ceremonial county of the East Riding of Yorkshire, and it serves local residents and businesses with Internet and telephony services. It was listed on the London Stock Exchange but is now privately owned by Macquarie Group.
Digital access carrier system (DACS) is the name used by British Telecom in the United Kingdom for a 0+2 pair gain system.
Direct inward dialling (DID), also called direct dial-in (DDI) in Europe and Oceania, is a telecommunication service offered by telephone companies to subscribers who operate a private branch exchange (PBX) system. The feature provides service for multiple telephone numbers over one or more analog or digital physical circuits to the PBX, and transmits the dialed telephone number to the PBX so that a PBX extension is directly accessible for an outside caller, possibly by-passing an auto-attendant.
1-5-7-1 is the name of a family of calling features in the United Kingdom, for residential and business telephone lines and for mobile telephones, that are provided by BT Group and several other telephone service providers. The family is named after the telephone number 1571, the special service number that is used to access it. Call Minder is the name of BT's highest level of 1571 service.
Phonewords are mnemonic phrases represented as alphanumeric equivalents of a telephone number. In many countries, the digits on the telephone keypad also have letters assigned. By replacing the digits of a telephone number with the corresponding letters, it is sometimes possible to form a whole or partial word, an acronym, abbreviation, or some other alphanumeric combination.
BT Wholesale and Ventures is a division of United Kingdom telecommunications company BT Group that provides voice, broadband, data, hosted communication, managed network and IT services to communications providers (CPs) in Great Britain, including BT's other divisions: BT Consumer, BT Business and Public Sector and EE. They also offer services for media companies and broadcasters, and its ventures side offers a range of products and services. It provides the voice services to UK customers via 999, 118 500 and Next Generation Text Service, which helps those who can’t hear or speak on the phone. The division is also leading the BT thinking on the internet of things.
BT Highway was a UK retail ISDN2e service from British Telecom which was announced in November 1997 and withdrawn in February 2007. In the domestic market, it was sold as BT Home Highway and for small businesses, BT Business Highway. These names were used simply to differentiate billing schemes; the hardware for both services used the name BT Highway. Unlike regular ISDN2e service where only a digital S interface is provided BT Highway provided both digital and analogue connections simplifying migration from regular POTS service.
In the United States of America, Canada, and other countries participating in the North American Numbering Plan, a toll-free telephone number has one of the area codes 800, 833, 844, 855, 866, 877, and 888.
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