Dual-tone multi-frequency signaling (DTMF) is a telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers. DTMF was first developed in the Bell System in the United States, and became known under the trademark Touch-Tone for use in push-button telephones supplied to telephone customers, starting in 1963. DTMF is standardized as ITU-T Recommendation Q.23. It is also known in the UK as MF4.
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.
An emergency telephone number is a number that allows a caller to contact local emergency services for assistance. The emergency number differs from country to country; it is typically a three-digit number so that it can be easily remembered and dialed quickly. Some countries have a different emergency number for each of the different emergency services; these often differ only by the last digit.
Plain old telephone service (POTS), or plain ordinary telephone system, is a retronym for voice-grade telephone service employing analog signal transmission over copper loops. POTS was the standard service offering from telephone companies from 1876 until 1988 in the United States when the Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) was introduced, followed by cellular telephone systems, and voice over IP (VoIP). POTS remains the basic form of residential and small business service connection to the telephone network in many parts of the world. The term reflects the technology that has been available since the introduction of the public telephone system in the late 19th century, in a form mostly unchanged despite the introduction of Touch-Tone dialing, electronic telephone exchanges and fiber-optic communication into the public switched telephone network (PSTN).
Caller identification is a telephone service, available in analog and digital telephone systems, including voice over IP (VoIP), that transmits a caller's telephone number to the called party's telephone equipment when the call is being set up. The caller ID service may include the transmission of a name associated with the calling telephone number, in a service called Calling Name Presentation (CNAM). The service was first defined in 1993 in International Telecommunication Union—Telecommunication Standardization Sector (ITU-T) Recommendation Q.731.3.
999 is an official emergency telephone number in a number of countries which allows the caller to contact emergency services for urgent assistance. Countries and territories using the number include Bahrain, Bangladesh, Botswana, Eswatini, Ghana, Guernsey, Hong Kong, Ireland, Isle of Man, Jersey, Kenya, Macau, Malaysia, Mauritius, Poland, Qatar, Sudan, Saudi Arabia, Singapore, Trinidad and Tobago, Seychelles, Uganda, the United Arab Emirates, the United Kingdom, and Zimbabwe.
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.
Wardialing is a technique to automatically scan a list of telephone numbers, usually dialing every number in a local area code to search for modems, computers, bulletin board systems and fax machines. Hackers use the resulting lists for various purposes: hobbyists for exploration, and crackers—malicious hackers who specialize in breaching computer security—for guessing user accounts, or locating modems that might provide an entry-point into computer or other electronic systems. It may also be used by security personnel, for example, to detect unauthorized devices, such as modems or faxes, on a company's telephone network.
A telephone call is a connection over a telephone network between the called party and the calling party.
The public switched telephone network (PSTN) is the aggregate of the world's telephone networks that are operated by national, regional, or local telephony operators. It provides infrastructure and services for public telecommunication. The network consist of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, interconnected by switching centers, such as central offices, network tandems, and international gateways, which allow telephone users to communicate with each other.
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 the early days of telephony, companies used manual telephone switchboards, and switchboard operators connected calls by inserting a pair of phone plugs into the appropriate jacks. They were gradually phased out and replaced by automated systems, first those allowing direct dialing within a local area, then for long-distance and international direct dialing.
In communications, Circuit Switched Data (CSD) is the original form of data transmission developed for the time-division multiple access (TDMA)-based mobile phone systems like Global System for Mobile Communications (GSM). After 2010 many telecommunication carriers dropped support for CSD, and CSD has been superseded by GPRS and EDGE (E-GPRS).
The Government Emergency Telecommunications Service (GETS) is a White House-directed emergency telephone service provided by a division of the Department of Homeland Security. GETS uses enhancements based on existing commercial technology
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.
Ringing tone is a signaling tone in telecommunication that is heard by the originator of a telephone call while the destination terminal is alerting the receiving party. The tone is typically a repeated cadence similar to a traditional power ringing signal (ringtone), but is usually not played synchronously. Various telecommunication groups, such as the Bell System and the General Post Office (GPO) developed standards, in part taken over by the European Telecommunications Standards Institute (ETSI) and other standards bodies. With modern cell phone and smartphone technology ringing tone can be customized and even used for advertising.
A party line is a local loop telephone circuit that is shared by multiple telephone service subscribers.
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.
Call management is the process of designing and implementing inbound telephone call parameters, which govern the routing of these calls through a network. The process is most prominently utilized by corporations and the call centre industry and has its highest effectiveness when call logging software tools are used. Calls are routed according to the set up of calling features within the given system such as Call queues, IVR menus, Hunt groups and Recorded announcements. Call features provide a customised experience for the caller and maximize the efficiency of inbound call handling. Call management parameters can specify how calls are distributed according to an operator's skill level in relation to a call, the time and/or date of a call, the location of the caller or through automatic routing processes.
A telephone exchange, telephone switch, or central office is a telecommunications system used in the public switched telephone network (PSTN) or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between subscribers.
