A diagram of an Autovon telephone keypad with the four precedence levels
A silver box is a modified DTMF keypad that adds four additional keys. This gives four columns of four keys each (16 total) instead of three columns (in the standard 12-pushbutton handset).
In the now-obsolete Autovon phone system these keys, used to set priority of a military call, were the red buttons in the photo on the right. Autovon included four precedence levels: Routine (no special tone), Priority (D), Immediate (C) and Flash (B) with Flash Override (A) as a capability. Each had the ability to interrupt lower-priority calls in progress if all trunks were busy. Each was activated using a button in an additional column of the keypad:
A (697+1633Hz): Flash Override (FO)
B (770+1633Hz): Flash (F)
C (852+1633Hz): Immediate (I)
D (941+1633Hz): Priority (P)
Autovon was replaced in the early 1990s by the Defense Switched Network; much of its infrastructure is now dismantled. Amateur radio equipment continues to be manufactured with 16-key DTMF keypads, keeping extra tones available for on-air use to control remote apparatus such as radio repeater stations. These tone pairs (labelled A, B, C, D) are rarely used.
Conversion of twelve-button keypads was usually accomplished with the addition of a toggle switch and a crystal that switched one column of a standard phone keypad into the "fourth column" used to generate 1633Hz as the higher of the two tones output on a keypress.
Modern phones with an integrated circuit based DTMF generator can frequently be modified by simply soldering a wire from the 1633Hz leg to a switch that toggles between that leg and the 1477Hz leg for the rightmost column of keys.[1]
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 rotary dial is a component of a telephone or a telephone switchboard that implements a signaling technology in telecommunications known as pulse dialing. It is used when initiating a telephone call to transmit the destination telephone number to a telephone exchange.
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.
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.
A blue box is an electronic device that produces tones used to generate the in-band signaling tones formerly used within the North American long-distance telephone network to send line status and called number information over voice circuits. This allowed an illicit user, referred to as a "phreaker", to place long-distance calls, without using the network's user facilities, that would be billed to another number or dismissed entirely as an incomplete call. A number of similar "color boxes" were also created to control other aspects of the phone network.
A telephone keypad is a keypad installed on a push-button telephone or similar telecommunication device for dialing a telephone number. It was standardized when the dual-tone multi-frequency signaling (DTMF) system was developed in the Bell System in the United States in the 1960s that replaced rotary dialing originally developed in electromechanical switching systems. Because of the installed abundance of rotary dial equipment well into the 1990s, many telephone keypads were also designed to produce loop-disconnect pulses electronically, and some could be optionally switched to produce either DTMF or pulses.
Call waiting is a telephone service where a subscriber can accept a second incoming telephone call by placing an in-progress call on hold—and may also switch between calls. With some providers it can be combined with additional features such as conferencing, call forwarding, and caller ID. Call waiting is intended to alleviate the need to have more than one telephone line or number for voice communications.
In telephony, multi-frequency signaling (MF) is a type of signaling that was introduced by the Bell System after World War II. It uses a combination of audible tones for address transport and supervision signaling on trunk lines between central offices. The signaling is sent in-band over the same channel as the bearer channel used for voice traffic.
In telecommunications, in-band signaling is the sending of control information within the same band or channel used for data such as voice or video. This is in contrast to out-of-band signaling which is sent over a different channel, or even over a separate network. In-band signals may often be heard by telephony participants, while out-of-band signals are inaccessible to the user. The term is also used more generally, for example of computer data files that include both literal data, and metadata and/or instructions for how to process the literal data.
A lineman's handset is a special type of telephone used by technicians for installing and testing local loop telephone lines. It is also called a test set, butt set, or buttinski.
The Improved Mobile Telephone Service (IMTS) was a pre-cellular VHF/UHF radio system which linked to the public telephone network. IMTS was the radiotelephone equivalent of land dial phone service. Introduced in 1964, it replaced Mobile Telephone Service (MTS) and improved on most MTS systems by offering direct-dial rather than connections through a live operator, and full-duplex operation so both parties could talk at the same time.
The Western Electric model 500 telephone series was the standard domestic desk telephone set issued by the Bell System in North America from 1950 through the 1984 Bell System divestiture. Millions of model 500-series phones were produced and were present in most homes in North America. Many are still in use today because of their durability and ample availability. Its modular construction compared to previous types simplified manufacture and repair, and facilitated a large number of variants with added features.
On analog telephone lines with special services, a flash or register-recall signal is used to control functions on the public telephone exchange, PBX or VoIP ATA.
Apple Inc. has designed and developed many external keyboard models for use with families of Apple computers, such as the Apple II, Mac, and iPad. The Magic Keyboard and Magic Keyboard with Numeric Keypad designed to be used via either Bluetooth and USB connectivity, and have integrated rechargeable batteries; The Smart Keyboard and Magic Keyboard accessories for iPads are designed to be directly attached to and powered by a host iPad. All current Apple keyboards utilize low-profile key designs, and common modifier keys.
Japanese input methods are used to input Japanese characters on a computer.
In a conventional, analog two-way radio system, a standard radio has noise squelch or carrier squelch, which allows a radio to receive all transmissions. Selective calling is used to address a subset of all two-way radios on a single radio frequency channel. Where more than one user is on the same channel, selective calling can address a subset of all receivers or can direct a call to a single radio. Selective calling features fit into two major categories—individual calling and group calling. Individual calls generally have longer time-constants: it takes more air-time to call an individual radio unit than to call a large group of radios.
The Nokia N93i is a smartphone produced by Nokia, announced on 8 January 2007 and released the same month. It is part of the Nseries line and is a redesign of the Nokia N93. The N93i runs on Symbian OS version 9.1, with the S60 3rd Edition user interface. Like the N93, it is a clamshell and swivel design with a camera and landscape position.
The LG enV3 is a mobile phone built by LG Electronics, and released from Verizon Wireless in the United States and Telus Mobility in Canada. It succeeded the LG enV2. Along with a slimmer design, the enV3 also boasts a full keyboard, a 2.6-inch screen and a 3.0-megapixel camera. In addition to standard phone and text messaging capabilities, the enV3 can be used as a portable music player as well as Internet capabilities such as e-mail and web browsing. The phone is Bluetooth enabled.
The push-button telephone is a telephone that has buttons or keys for dialing a telephone number, in contrast to having a rotary dial as in earlier telephone instruments.
Dialling is the action of initiating a telephone call by operating the rotary dial or the telephone keypad of a telephone.
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