Interexchange carrier

Last updated

An interexchange carrier (IXC), in U.S. legal and regulatory terminology, is a type of telecommunication company, commonly called a long-distance telephone company. It is defined as any carrier that provides services across multiple local access and transport areas (interLATA). Calls made on telephone circuits within the local geographic area covered by one local network are handled only by that intraLATA carrier, commonly called a local telephone exchange carrier. Local calls are usually defined by connections made without additional charge whether the connected call is in the same LATA or connects to another LATA with no charge. IntraLATA usually refers to rated or toll calls between LATA within state boundaries, as opposed to interstate, or calls between LATAs in different states.

Contents

Call handling

An interexchange carrier handles traffic between telephone exchanges. Telephone exchanges are identified in the United States by the three-digit area code (NPA) and the central office prefix, which is the first three digits of the local telephone number (NPA-NXX). Different exchanges, or central offices, generally serve different geographic areas.

For voice traffic transfer, IXCs use softswitches and VoIP protocols and error correction.[ citation needed ] ITSPs can thereby connect between VoIP to POTS, computer to computer, computer to phone, and Internet Protocol devices to other phone services. [1]

Carrier identification code

Each carrier (interexchange or local exchange) is assigned a four-digit identification code, the carrier identification code (CIC) which was used with feature groups. The interexchange carrier to which calls from a subscriber line are routed by default is known as the presubscribed interexchange carrier (PIC). To give telephone users the possibility of opting for a different carrier on a call-by-call basis, carrier access codes (CAC) were devised. These consist of the digits 101 followed by the four-digit CIC. The CAC is dialed as a prefix immediately before dialing a long-distance telephone number.

In popular usage, CACs are often referred to as dial-around codes, because they allow "dialing around" the PIC. Sometimes they are even called "PIC codes", though this term is inaccurate, since the code is being used to avoid the PIC, not to use its services.

When CICs were first introduced in 1983, they were only three digits long, and the CAC consisted of the digits 10 followed by the three-digit CIC. In 1998, the CIC had to be extended to four digits. Existing carriers' codes were prefixed with 10. Thus, a pre-1998 CAC of the form 10-XXX became 101-0XXX. [2] Since the CACs starting with 10-10 are generally the oldest and best-known ones, CACs are sometimes referred to as 10-10 codes.

See also

Related Research Articles

Local exchange carrier (LEC) is a regulatory term in telecommunications for the local telephone company.

<span class="mw-page-title-main">North American Numbering Plan</span> Integrated telephone numbering plan of twenty North American countries

The North American Numbering Plan (NANP) is a telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Zone 1 and has the telephone country code 1. Some North American countries, most notably Mexico, do not participate with the NANP.

411 is a telephone number for local directory assistance in Canada and the United States. Until the early 1980s, 411 – and the related 113 number – were free to call in most jurisdictions.

A toll-free telephone number or freephone number is a telephone number that is billed for all arriving calls. For the calling party, a call to a toll-free number from a landline is free of charge. A toll-free number is identified by a dialing prefix similar to an area code. The specific service access varies by country.

A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, reachable by a system of destination code routing. Telephone numbering plans are defined in each of the administrative regions of the public switched telephone network (PSTN) and in private telephone networks.

In telecommunications, an area code overlay complex is a telephone numbering plan that assigns multiple area codes to a geographic numbering plan area (NPA). Area code overlays are implemented in territories of the North American Numbering Plan (NANP) to mitigate exhaustion of central office codes in growth areas. The method has been in use since 1992, and has been the exclusive method of area code relief since 2007.

Seven-digit dialing is a telephone dialing procedure customary in some territories of the North American Numbering Plan (NANP) for dialing telephone numbers in the same numbering plan area (NPA). NANP telephone numbers consist of ten digits, of which the leading three are the area code. In seven-digit dialing it is not necessary to dial the area code. The procedure is also sometimes known as local format or network format.

In telecommunications, a long-distance call (U.S.) or trunk call is a telephone call made to a location outside a defined local calling area. Long-distance calls are typically charged a higher billing rate than local calls. The term is not necessarily synonymous with placing calls to another telephone area code.

Telephone number pooling, thousands-block number pooling, or just number pooling, is a method of allocating telephony numbering space of the North American Numbering Plan in the United States. The method allocates telephone numbers in blocks of 1,000 consecutive numbers of a given central office code to telephony service providers. In the United States it replaced the practice of allocating all 10,000 numbers of a central office prefix at a time. Under number pooling, the entire prefix is assigned to a rate center, to be shared among all providers delivering services in that rate center. Number pooling reduced the quantity of unused telephone numbers in markets which have been fragmented between multiple service providers, avoided central office prefix exhaustion in high growth areas, and extended the lifetime of the North American telephone numbering plan without structure changes of telephone numbers. Telephone number pooling was first tested for area code 847 in Illinois in June 1998, and became national policy in a series of Federal Communications Commission (FCC) orders from 2000 to 2003.

Direct inward dialing (DID), also called direct dial-in (DDI) in Europe and Oceania, is a telecommunication service offered by telephone companies to subscribers who operate private branch exchange (PBX) systems. 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.

In telecommunication, a dial plan establishes the permitted sequences of digits dialed by telephone subscriber and the manner in which a telephone switch interprets these digits within the definitions of the prevailing telephone numbering plan. Dial plans in the public switched telephone network referred to as dialing procedures.

<span class="mw-page-title-main">Telephone numbers in Singapore</span>

Telephone numbers in Singapore, also known as the National Numbering Plan, are regulated by the Info-communications Media Development Authority (IMDA). Due to the small geographical size of Singapore, there are no area or trunk codes; all numbers belong to one numbering area, and thus come in the same 8-digit format. Numbers are categorised based on the first digit, thus providing ten possible categories, of which six are currently in use and the remaining four reserved for future usage.

Area code 246 is the telephone area code in the North American Numbering Plan (NANP) for Barbados. The sequence 246 spells BIM on an alpha-numeric telephone keypad, a nickname for the island.

Area code 700 of the North American Numbering Plan is a service access code (SAC) implemented by interexchange carriers. It is reserved for carrier-specific number assignments to special services or destinations. It was introduced in 1983 for providing customized services in anticipation of the introduction of long-distance competition in the United States, but this usage has been deprecated. The area code has found renewed usage for custom calling services by voice over IP service providers and in software-defined voice networks.

A feature group, in North American telephone industry jargon, is most commonly used to designate various standard means of access by callers to competitive long-distance services. They defined switching arrangements from local exchange carriers central offices to interexchange carriers. These arrangements were described in an official tariff of the National Exchange Carrier Association, filed with the Federal Communications Commission (FCC).

Telephone numbers in Canada follow the fixed-length format of the North American Numbering Plan (NANP) of a three-digit area code, a three-digit central office code, and a four-digit station or line code. This is represented as NPA NXX XXXX.

<span class="mw-page-title-main">Telephone number</span> Sequence of digits assigned to a telephone subscription

A telephone number is a sequence of digits assigned to a landline telephone subscriber station connected to a telephone line or to a wireless electronic telephony device, such as a radio telephone or a mobile telephone, or to other devices for data transmission via the public switched telephone network (PSTN) or other public and private networks.

Toll-free telephone numbers in the North American Numbering Plan have the area code prefix 800, 833, 844, 855, 866, 877, and 888. Additionally, area codes 822, 880 through 887, and 889 are reserved for toll-free use in the future. 811 is excluded because it is a special dialing code in the group NXX for various other purposes.

In the administration of the North American Numbering Plan, central office code protection is a numbering policy for maintaining local seven-digit dialing in communities that extend on both sides of the boundary line between multiple numbering plan areas (NPAs), such as in cross-border towns on state lines. Code protection prevents the use of the same telephone number on both sides by not assigning the same central office code of one NPA in the adjacent NPA.

In the North American Numbering Plan, a rate center is a geographically-specified area used for determining mileage and/or usage dependent rates in the public switched telephone network.

References

  1. "About Softswitches in general". IXC. 19 September 2012.
  2. See the FCC's FAQ on the subject.