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In the evolution of modern telecommunications systems there was a requirement to connect large numbers of low-speed access devices with large telephone company 'central office' switches over common paths. During the first generations of digital networks, analog signals were digitized on line cards attached to the telephone exchange switches. In an effort to reduce local loop costs, it was decided to push this conversion closer to the customer premises by deploying small conversion devices in customer neighborhoods. These devices would combine multiple digital signals on a single link to a larger telephone switch, which would provide service to the customer. These devices were initially called remote concentrators or simply remotes.
Pulse dialing is a signaling technology in telecommunications in which a direct current local loop circuit is interrupted according to a defined coding system for each signal transmitted, usually a digit. This lends the method the often used name loop disconnect dialing. In the most common variant of pulse dialing, decadic dialing, each of the ten Arabic numerals are encoded in a sequence of up to ten pulses. The most common version decodes the digits 1 through 9, as one to nine pulses, respectively, and the digit 0 as ten pulses. Historically, the most common device to produce such pulse trains is the rotary dial of the telephone, lending the technology another name, rotary dialing.
Direct distance dialing (DDD) is a telecommunication service feature in which a caller may, without operator assistance, call any other user outside the local calling area. Direct dialing by subscribers typically requires extra digits to be dialed as prefixes than for dialing within the local area or within an area code. DDD also extends beyond the boundaries of national public telephone network, in which case it is called international direct dialing or international direct distance dialing (IDDD).
In telephony, ringdown is a method of signaling an operator in which telephone ringing current is sent over the line to operate a lamp or cause the operation of a self-locking relay known as a drop.
The Automatic Voice Network was a worldwide American military telephone system. The system was built starting in 1963, based on the Army's existing Switch Communications Automated Network (SCAN) system. In June 1966 the Air Defense Command voice network was cut over to the new service. In 1969, AUTOVON switching centers opened in the United Kingdom, and later in other European countries, Asia, the Middle East, and Panama. It was a major part of the Defense Communications System (DCS), providing non-secure switched voice services. The system was replaced in the early 1990s by the Defense Switched Network.
The North American Numbering Plan (NANP) is a telephone numbering plan that encompasses twenty-five distinct regions in twenty countries primarily in North America, including the Caribbean. Some North American countries, most notably Mexico, do not participate in the NANP.
Subscriber trunk dialling is a telephone system allowing subscribers to dial trunk calls without operator assistance. The term was introduced when it first became possible for long-distance calls to be dialed directly, and is now rarely used where calls to any destination can be dialed.
A vertical service code (VSC) is a sequence of digits and the signals star (*) and number sign (#) dialed on a telephone keypad or rotary dial to enable or disable certain telephony service features. Some vertical service codes require dialing of a telephone number after the code sequence. On a touch tone telephone, the codes are usually initiated with the star key, resulting in the commonly used name star codes. On rotary dial telephones, the star is replaced by dialing 11.
The public switched telephone network (PSTN) is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telephony operators, providing infrastructure and services for public telecommunication. The PSTN consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all interconnected by switching centers, thus allowing most telephones to communicate with each other. Originally a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital in its core network and includes mobile and other networks, as well as fixed telephones.
In telecommunications, trunking is a way to provide network access to many clients by sharing a set of lines or frequencies instead of providing them individually. This is analogous to the structure of a tree with one trunk and many branches. Examples of this include telephone systems and the two-way radios commonly used by police agencies. Trunking, in the form of link aggregation and VLAN tagging, has been applied in computer networking as well.
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 administrative regions of the public switched telephone network (PSTN) and they are also present in private telephone networks. For public number systems, geographic location plays a role in the sequence of numbers assigned to each telephone subscriber.
Routing in the PSTN is the process used to route telephone calls across the public switched telephone network.
Global System for Mobile Communications (GSM) services are a standard collection of applications and features available to mobile phone subscribers all over the world. The GSM standards are defined by the 3GPP collaboration and implemented in hardware and software by equipment manufacturers and mobile phone operators. The common standard makes it possible to use the same phones with different companies' services, or even roam into different countries. GSM is the world's most dominant mobile phone standard.
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.
An intercept message is a telephone recording informing the caller that the call cannot be completed, for any of a number of reasons ranging from local congestion, to disconnection of the destination phone, number dial errors or network trouble along the route.
A digital subscriber line (DSL) modem is a device used to connect a computer or router to a telephone line which provides the digital subscriber line service for connection to the Internet, which is often called DSL broadband.
Foreign exchange service (FX) is an access service in a telecommunications network in which a telephone in a given exchange area is connected, via a private line, as opposed to a switched line, to a telephone exchange or central office in another exchange area, called the foreign exchange, rather than the local exchange area where the subscriber station equipment is located.
A telephone number is a sequence of digits assigned to a fixed-line 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.
A PSTN network topology is the switching network topology of a telephone network connected to the public switched telephone network (PSTN).
A telephone exchange or telephone switch is a telecommunications system used in the public switched telephone network or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between subscribers.
References
- ↑ "Federal Standard 1037C", United States General Services Administration (1996)
- ↑ Weik, Martin (1997). Fiber Optics Standard Dictionary (illustrated ed.). Springer Science & Business Media. p. 369. ISBN 9780412122415.
- ↑ The Army communicator. 15. U.S. Army Signal School. 1990.
- ↑ Hura, Gurdeep S.; Singhal, Mukesh (2001). Data and Computer Communications: Networking and Internetworking (illustrated ed.). CRC. p. 576. ISBN 9781420041316.
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