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.
A telephone, or phone, is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly. A telephone converts sound, typically and most efficiently the human voice, into electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user.
A teleprinter is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Initially they were used in telegraphy, which developed in the late 1830s and 1840s as the first use of electrical engineering. The machines were adapted to provide a user interface to early mainframe computers and minicomputers, sending typed data to the computer and printing the response. Some models could also be used to create punched tape for data storage and to read back such tape for local printing or transmission.
The 5ESS Switching System is a Class 5 telephone electronic switching system developed by Western Electric for the American Telephone and Telegraph Company (AT&T) and the Bell System in the United States.
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.
Telephony is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is intimately linked to the invention and development of the telephone.
In electronics, a crossbar switch is a collection of switches arranged in a matrix configuration. A crossbar switch has multiple input and output lines that form a crossed pattern of interconnecting lines between which a connection may be established by closing a switch located at each intersection, the elements of the matrix. Originally, a crossbar switch consisted literally of crossing metal bars that provided the input and output paths. Later implementations achieved the same switching topology in solid state semiconductor chips. The cross-point switch is one of the principal switch architectures, together with a rotary switch, memory switch, and a crossover switch.
Phreaking is a slang term coined to describe the activity of a culture of people who study, experiment with, or explore telecommunication systems, such as equipment and systems connected to public telephone networks. The term phreak is a sensational spelling of the word freak with the ph- from phone, and may also refer to the use of various audio frequencies to manipulate a phone system. Phreak, phreaker, or phone phreak are names used for and by individuals who participate in phreaking.
A blue box is an electronic device that generates the in-band signaling audio tones formerly used to control long-distance telephone exchanges. By generating the same tones employed by a telephone operator's dialing console, a blue box user could route their own calls and bypass the normal toll collection by the telephone company. Developed in the 1960s, the most typical use of a blue box was to place free long-distance telephone calls. A related device, the black box, enabled one to receive calls which were free to the caller. The blue box no longer works in most Western nations, since to prevent this form of fraud, modern switching systems no longer use in-band signaling. Instead, signaling occurs on an out-of-band channel that cannot be accessed from the line the caller is using, a system called Common Channel Interoffice Signaling or CCIS.
Twistor memory is a form of computer memory formed by wrapping magnetic tape around a current-carrying wire. Operationally, twistor was very similar to core memory. Twistor could also be used to make ROM memories, including a re-programmable form known as piggyback twistor. Both forms were able to be manufactured using automated processes, which was expected to lead to much lower production costs than core-based systems.
The answering machine, answerphone or message machine, also known as telephone answering machine in the UK and some Commonwealth countries, ansaphone or ansafone, or telephone answering device (TAD), is used for answering telephones and recording callers' messages.
In telecommunications, trunking is a method for a system 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.
Broadcast automation incorporates the use of broadcast programming technology to automate broadcasting operations. Used either at a broadcast network, radio station or a television station, it can run a facility in the absence of a human operator. They can also run in a "live assist" mode when there are on-air personnel present at the master control, television studio or control room.
A business telephone system is a multiline telephone system typically used in business environments, encompassing systems ranging from the small key telephone system (KTS) to the large private branch exchange (PBX).
The New York Telephone Company (NYTel) was organized in 1896, taking over the New York City operations of the American Bell Telephone Company.
Area code 408 is a California telephone area code that was split from area code 415 as a flash-cut in 1959. Area code 669 is an overlay of 408 that became effective on November 20, 2012. It covers most of Santa Clara County and Northern Santa Cruz County and includes Gilroy, Morgan Hill, Saratoga, Los Gatos, Monte Sereno, Milpitas, Sunnyvale, Santa Clara, Cupertino, and San Jose.
A reed relay is a type of relay that uses an electromagnet to control one or more reed switches. The contacts are of magnetic material and the electromagnet acts directly on them without requiring an armature to move them. Sealed in a long, narrow glass tube, the contacts are protected from corrosion. The glass envelope may contain multiple reed switches or multiple reed switches can be inserted into a single bobbin and actuate simultaneously. Reed switches have been manufactured since the 1930s.
Automatic message accounting (AMA) provides detailed accounting for telephone calls. When direct distance dialing (DDD) was introduced in the US, message registers no longer sufficed for dialed telephone calls. The need to record the time and phone number of each long distance call was met by electromechanical data processing equipment.
A telephone exchange is a telecommunications system used in the public switched telephone network or in large enterprises. An exchange consists of electronic components and in older systems also human operators that interconnect (switch) telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between subscribers.
The telex network was a public switched network of teleprinters similar to a telephone network, for the purposes of sending text-based messages. Telex was a major method of sending written messages electronically between businesses in the post-World War II period. Its usage went into decline as the fax machine grew in popularity in the 1980s.
