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Signalling System No. 5
The Signaling System No. 5 (SS5) is a multi-frequency (MF) telephone signaling system that was in use from the 1970s for International Direct Distance Dialing ( IDDD). Internationally it became known as CCITT5 or CC5.ITU-T Recommendation Q.140-Q.180 - Specifications of Signalling System No. 5 It was also nicknamed ''Atlantic Code'' because it was used for the first IDDD connections between Europe and North America. Signaling systems in use at the time were designed for in-band signaling, meaning they used the same channel as the media that they controlled. SS5 was designed for inter-continental traff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multi-frequency
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 ( telephone number) 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. Multi-frequency signaling defines electronic signals that consist of a combination of two audible frequencies, usually selected from a set of six frequencies. Over several decades, various types of MF signaling were developed, including national and international varieties. The CCITT standardization process specified the American Bell System version as ''Regional Standard No. 1'', or Signalling System R1, and a corresponding European standard as Signalling System R2. Both were largely replaced by digital systems, such as Signalling System 7, which operate out-of-band on a separate data network. Because o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-out-of-five Code
A two-out-of-five code is a constant-weight code that provides exactly ten possible combinations of two bits, and is thus used for representing the decimal digits using five bits. Each bit is assigned a weight, such that the set bits sum to the desired value, with an exception for zero. According to Federal Standard 1037C: * each decimal digit is represented by a binary numeral consisting of five bits of which two are of one kind, called ''ones'', and three are of the other kind, called ''zeros'', and * the usual weights assigned to the bit positions are 0-1-2-3-6. However, in this scheme, zero is encoded as binary ''01100''; strictly speaking the 0-1-2-3-6 previously claimed is just a mnemonic device. The weights give a unique encoding for most digits, but allow two encodings for 3: 0+3 or 10010 and 1+2 or 01100. The former is used to encode the digit 3, and the latter is used to represent the otherwise unrepresentable zero. The IBM 7070, IBM 7072, and IBM 7074 computers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signalling System No
A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology. In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The '' IEEE Transactions on Signal Processing'' includes audio, video, speech, image, sonar, and radar as examples of signals. A signal may also be defined as observable change in a quantity over space or time (a time series), even if it does not carry information. In nature, signals can be actions done by an organism to alert other organisms, ranging from the release of plant chemicals to warn nearby plants of a predator, to sounds or motions made by animals to alert other animals of food. Signaling occurs in all organisms even at cellular levels, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Draper
John Thomas Draper (born March 11, 1943), also known as Captain Crunch, Crunch, or Crunchman after a toy boatswain's call whistle once given away in boxes of Cap'n Crunch breakfast cereal that for some years could be used to make free long distance phone calls, is an American computer programmer and former phone phreak. He is a widely known figure within the hacker and computer security community. He is primarily known as a colorful and unconventional figure in Silicon Valley history and lore. He befriended and influenced Steve Wozniak and Steve Jobs in the years before they founded Apple Computer. His determined probing and exploration of the telephone network earned him a reputation for his technical acumen. However, his activities sometimes crossed ethical lines, leading to criminal charges for toll fraud and prison time. In the 1970s and 1980s, he worked intermittently as a software engineer for Apple and Autodesk and briefly ran his own software company, producing the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Box
A blue box is an Electronics, 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. During that period, charges associated with long-distance calling were commonplace and could be significant, depending on the time, duration and destination of the call. A blue box device allowed for circumventing these charges by enabling an illicit user, referred to as a "Phreaking, phreaker", to place long-distance calls, without using the network's user facilities, that would be billed to another number or dismissed entirely by the telecom company's billing system as an incomplete call. A number of similar "color boxes" were also created to control other aspects of the phone network. First developed in the 1960s and used by a small phreaker community, the introduction of low-cost microelectronics in the early 1970s greatly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2600 Hz
2600 hertz (2600 Hz) is a frequency in hertz (cycles per second) that was used in telecommunication signaling in mid-20th century long-distance telephone networks using carrier systems. Tone signaling carrier systems operated in the standard telephony voice frequency range ( to ). They replaced direct current (D.C.) signaling on toll trunk lines because they could be used with any type of toll facility over any length of transmission line that was suitable for voice transmissions. This included transmission through line repeaters and other facilities that would distort, block, or otherwise prohibit D.C. loop-disconnect signaling, such as rotary dial pulses, and on-hook/off-hook signaling. Common frequencies for this purpose were , , , , and , the latter being just outside the voice range. These signaling systems were continuous tone methods, so that the idle condition of a trunk line could easily be detected by the presence of the appropriate signaling frequency, in cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line Signaling
Line signaling is a class of telecommunications signaling protocols. Line signaling is responsible for off-hook, ringing signal, answer, ground start, on-hook unidirectional supervision messaging in each direction from calling party to called party and vice versa. After an off-hook, line signaling initiates register signaling to accomplish the exchange of telephone numbers of called party and in more modern line-signaling protocols, the calling party as well. While register signaling occurs, line signaling remains quiescent unless the calling party goes on-hook or an abnormal cessation of the call occurs, such as due to equipment malfunction or shutdown or due to network outage upstream in that call-attempt's series of spanned trunks. Line signaling can be conveyed in a single DS0 channel of a trunk. In modern PCM telecommunications, line signaling is represented by the ABCD bits in DS0 #16 of an E1 or a selected DS0 within a T1. Line signaling can also be conveyed with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Register Signaling
In telecommunications, register signaling provides addressing information, such as the calling and/or called telephone number A telephone number is the address of a Telecommunications, telecommunication endpoint, such as a telephone, in a telephone network, such as the public switched telephone network (PSTN). A telephone number typically consists of a Number, sequ .... R2 register signaling is an example. This is contrasted with line signaling. References Telephony signals {{telephony-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CCITT
The International Telecommunication Union Telecommunication Standardization Sector (ITU-T) is one of the three Sectors (branches) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Communication Technology, such as X.509 for cybersecurity, Y.3172 and Y.3173 for machine learning, and H.264/MPEG-4 AVC for video compression, between its Member States, Private Sector Members, and Academia Members. The World Telecommunication Standardization Assembly (WTSA), the sector's governing conference, convenes every four years. ITU-T has a permanent secretariat called the Telecommunication Standardization Bureau (TSB), which is based at the ITU headquarters in Geneva, Switzerland. The current director of the TSB is Seizo Onoe (of Japan), whose 4-year term commenced on 1 January 2023. Seizo Onoe succeeded Chaesub Lee of South Korea, who was director from 1 January 2015 until 31 December 2022. Prima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Distance Dialing
Direct distance dialing (DDD) is a telecommunications service in North America by which a caller may call any other subscriber outside the local calling area without operator assistance, DDD was introduced in the United States in 1951, on a trial basis, with service from Englewood, New Jersey. Direct long-distance dialing by subscribers requires extra digits, called an area code, to be dialed as prefixes to the directory telephone number of the destination. International Direct Distance Dialing (IDDD) extends the system beyond the geographic boundaries of the North American Numbering Plan (NANP). History The first direct-dialed long-distance telephone calls were possible in the New Jersey communities of Englewood and Teaneck. Customers of the ENglewood 3, ENglewood 4 and TEaneck 7 exchanges, who could already dial telephone numbers in the New York City area, could place calls to eleven major cities across the United States by dialing the three-digit area code and the seven-di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell System
The Bell System was a system of telecommunication companies, led by the Bell Telephone Company and later by the AT&T Corporation, American Telephone and Telegraph Company (AT&T), that dominated the telephone services industry in North America for over 100 years from its creation in 1877 until United States v. AT&T (1982), its antitrust breakup in 1983. The system of companies was often colloquially called Ma Bell (as in "Mother Bell"), as it held a vertical monopoly over telecommunication products and services in most areas of the United States and Canada. At the time of the breakup of the Bell System in the early 1980s, it had assets of $150 billion (equivalent to $ billion in ) and employed over one million people. Beginning in the 1910s, American antitrust regulators had been observing and accusing the Bell System of abusing its monopoly power, and had brought legal action multiple times over the decades. In 1974 the United States Department of Justice Antitrust Division, Anti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echo Suppressor
Echo suppression and echo cancellation are methods used in telephony to improve voice quality by preventing echo from being created or removing it after it is already present. In addition to improving subjective audio quality, echo suppression increases the capacity achieved through silence suppression by preventing echo from traveling across a telecommunications network. Echo suppressors were developed in the 1950s in response to the first use of satellites for telecommunications. Echo suppression and cancellation methods are commonly called acoustic echo suppression (AES) and acoustic echo cancellation (AEC), and more rarely line echo cancellation (LEC). In some cases, these terms are more precise, as there are various types and causes of echo with unique characteristics, including acoustic echo (sounds from a loudspeaker being reflected and recorded by a microphone, which can vary substantially over time) and line echo (electrical impulses caused by, e.g., coupling between the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
