1.
Retronym
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A retronym is a neologism for a word created to differentiate between two words, where previously no clarification was required. Advances in technology are responsible for the coinage of retronyms. For example, the acoustic guitar was coined at the advent of electric guitars. Since the end of the 19th century, most bicycles have been expected to have two equal sized wheels, and the type has been renamed penny-farthing or high-wheeler bicycle. Similarly, the term cisgender was coined to describe persons who identify with the gender they were assigned at birth, the term retronym was coined by Frank Mankiewicz in 1980 and popularized by William Safire in The New York Times Magazine. In 2000 The American Heritage Dictionary became the first major dictionary to include the word retronym, back-formation Backronym Contrastive focus reduplication -onym Protologism
2.
Telephone
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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. In 1876, Scottish emigrant Alexander Graham Bell was the first to be granted a United States patent for a device that produced clearly intelligible replication of the human voice and this instrument was further developed by many others. The telephone was the first device in history that people to talk directly with each other across large distances. Telephones rapidly became indispensable to businesses, government, and households, the essential elements of a telephone are a microphone to speak into and an earphone which reproduces the voice in a distant location. Until approximately the 1970s most telephones used a dial, which was superseded by the modern DTMF push-button dial. The receiver and transmitter are usually built into a handset which is held up to the ear, the dial may be located either on the handset, or on a base unit to which the handset is connected. The transmitter converts the sound waves to electrical signals which are sent through the network to the receiving phone. The receiving telephone converts the signals into audible sound in the receiver, telephones permit duplex communication, meaning they allow the people on both ends to talk simultaneously. The first telephones were connected to each other from one customers office or residence to another customers location. Being impractical beyond just a few customers, these systems were replaced by manually operated centrally located switchboards. For greater mobility, various systems were developed for transmission between mobile stations on ships and automobiles in the middle 20th century. Hand-held mobile phone]s was introduced for personal service starting in 1973, by the late 1970s several mobile telephone networks operated around the world. In 1983, the Advanced Mobile Phone System was launched, offering a standardized technology providing portability for users far beyond the residence or office. These analog cellular system evolved into digital networks with better security, greater capacity, better regional coverage, the public switched telephone network, with its hierarchical system of many switching centers, interconnects telephones around the world for communication with each other. With the standardized international numbering system, E.164, each line has an identifying telephone number. Although originally designed for voice communications, convergence has enabled most modern cell phones to have many additional capabilities. Since 1999, the trend for mobile phones is smartphones that integrate all mobile communication, a traditional landline telephone system, also known as plain old telephone service, commonly carries both control and audio signals on the same twisted pair of insulated wires, the telephone line. The control and signaling equipment consists of three components, the ringer, the hookswitch, and a dial, the ringer, or beeper, light or other device, alerts the user to incoming calls
3.
Integrated Services Digital Network
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It was first defined in 1988 in the CCITT red book. Prior to ISDN, the system was viewed as a way to transport voice. The key feature of ISDN is that it integrates speech and data on the same lines, the ISDN standards define several kinds of access interfaces, such as Basic Rate Interface, Primary Rate Interface, Narrowband ISDN, and Broadband ISDN. It offers circuit-switched connections, and packet-switched connections, in increments of 64 kilobit/s, in some countries, ISDN found major market application for Internet access, in which ISDN typically provides a maximum of 128 kbit/s bandwidth in both upstream and downstream directions. Channel bonding can achieve a data rate, typically the ISDN B-channels of three or four BRIs are bonded. ISDN is employed as the network, data-link and physical layers in the context of the OSI model, or could be considered a suite of digital services existing on layers 1,2, and 3 of the OSI model. In a videoconference, ISDN provides simultaneous voice, video, Integrated services refers to ISDNs ability to deliver at minimum two simultaneous connections, in any combination of data, voice, video, and fax, over a single line. Multiple devices can be attached to the line, and used as needed and that means an ISDN line can take care of most peoples complete communications needs at a much higher transmission rate, without forcing the purchase of multiple analog phone lines. It also refers to integrated switching and transmission in that telephone switching, the entry level interface to ISDN is the Basic Rate Interface, a 128 kbit/s service delivered over a pair of standard telephone copper wires. The 144 kbit/s payload rate is broken down into two 64 kbit/s bearer channels and one 16 kbit/s signaling channel and this is sometimes referred to as 2B+D. The T interface is an interface between a computing device and a terminal adapter, which is the digital equivalent of a modem. The S interface is a bus that ISDN consumer devices plug into. The R interface defines the point between a device and a terminal adapter which provides translation to and from such a device. BRI-ISDN is very popular in Europe but is less common in North America. It is also common in Japan — where it is known as INS64, the other ISDN access available is the Primary Rate Interface, which is carried over an E1 in most parts of the world. An E1 is 30 B channels of 64 kbit/s, one D channel of 64 kbit/s and this is often referred to as 30B+2D. In North America PRI service is delivered on one or more T1 carriers of 1544 kbit/s, a PRI has 23 B channels and 1 D channel for signalling. Inter-changeably but incorrectly, a PRI is referred to as T1 because it uses the T1 carrier format, a true T1 uses 24 channels of 64 kbit/s of in-band signaling
4.
Mobile phone
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A mobile phone is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area. The radio frequency link establishes a connection to the systems of a mobile phone operator. Most modern mobile telephone services use a network architecture, and, therefore. Mobile phones which offer these and more general computing capabilities are referred to as smartphones, the first handheld mobile phone was demonstrated by John F. Mitchell and Martin Cooper of Motorola in 1973, using a handset weighing c.4.4 lbs. In 1983, the DynaTAC 8000x was the first commercially available mobile phone. From 1983 to 2014, worldwide mobile phone subscriptions grew to seven billion, penetrating 100% of the global population. In first quarter of 2016, the top smartphone manufacturers were Samsung, Apple, a handheld mobile radio telephone service was envisioned in the early stages of radio engineering. In 1917, Finnish inventor Eric Tigerstedt filed a patent for a pocket-size folding telephone with a thin carbon microphone. Early predecessors of cellular phones included analog radio communications from ships, the race to create truly portable telephone devices began after World War II, with developments taking place in many countries. These 0G systems were not cellular, supported few simultaneous calls, the first handheld mobile phone was demonstrated by John F. Mitchell and Martin Cooper of Motorola in 1973, using a handset weighing c.4.4 lbs. The first commercial automated cellular network was launched in Japan by Nippon Telegraph and this was followed in 1981 by the simultaneous launch of the Nordic Mobile Telephone system in Denmark, Finland, Norway, and Sweden. Several other countries followed in the early to mid-1980s. These first-generation systems could support far more simultaneous calls but still used analog cellular technology, in 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone. In 1991, the digital cellular technology was launched in Finland by Radiolinja on the GSM standard. This sparked competition in the sector as the new operators challenged the incumbent 1G network operators, ten years later, in 2001, the third generation was launched in Japan by NTT DoCoMo on the WCDMA standard. This was followed by 3. 5G, 3G+ or turbo 3G enhancements based on the high-speed packet access family, allowing UMTS networks to have data transfer speeds. By 2009, it had become clear that, at point, 3G networks would be overwhelmed by the growth of bandwidth-intensive applications. Consequently, the industry began looking to data-optimized fourth-generation technologies, with the promise of speed improvements up to ten-fold over existing 3G technologies
5.
Dual-tone multi-frequency signaling
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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 by ITU-T Recommendation Q.23 and it is also known in the UK as MF4. The Touch-Tone system using a telephone keypad gradually replaced the use of dial and has become the industry standard for landline. Other multi-frequency systems are used for internal signaling within the telephone network, prior to the development of DTMF, telephone numbers were dialed by users with a loop-disconnect signaling, more commonly known as pulse dialing in the U. S. The exchange equipment responds to the dial pulses either directly by operating relays, the physical distance for which this type of dialing was possible was restricted by electrical distortions and was only possible on direct metallic links between end points of a line. Placing calls over longer distances required either operator assistance or provision of special subscriber trunk dialing equipment, operators used an earlier type of multi-frequency signaling. Multi-frequency signaling is a group of signaling methods that use a mixture of two pure tone sounds, various MF signaling protocols were devised by the Bell System and CCITT. This semi-automated signaling and switching proved successful in both speed and cost effectiveness, the DTMF system uses a set of eight audio frequencies transmitted in pairs to represent 16 signals, represented by the ten digits, the letters A to D, and the symbols # and *. AT&T described the product as a method for pushbutton signaling from customer stations using the transmission path. DTMF was known throughout the Bell System by the trademark Touch-Tone, the term was first used by AT&T in commerce on July 5,1960 and was introduced to the public on November 18,1963, when the first push-button telephone was made available to the public. It was a trademark by AT&T from September 4,1962 to March 13,1984. It is standardized by ITU-T Recommendation Q.23, in the UK, it is also known as MF4. Other vendors of compatible telephone equipment called the Touch-Tone feature tone dialing or DTMF, previously, terrestrial television stations used DTMF tones to control remote transmitters. The engineers had envisioned telephones being used to access computers, and they consulted with companies to determine the requirements. This led to the addition of the sign and asterisk or star keys as well as a group of keys for menu selection. Public payphones that accept credit cards use these codes to send the information from the magnetic strip. The AUTOVON telephone system of the United States Armed Forces used these signals to assert certain privilege, precedence is still a feature of military telephone networks, but using number combinations. For example, entering 93 before a number is a priority call, present-day uses of the A, B, C and D signals on telephone networks are few, and are exclusive to network control
6.
Telephone exchange
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A telephone exchange is a telecommunications system used in the public switched telephone network or in large enterprises. In historical perspective, telecommunication terms have been used with different semantics over time, the term telephone exchange is often used synonymously with central office, a Bell System term. Often, an office is defined as a building used to house the inside plant equipment of potentially several telephone exchanges. Such an area has also referred to as the exchange. Central office locations may also be identified in North America as wire centers, All central offices within a larger region, typically aggregated by state, were assigned a common numbering plan area code. For corporate or enterprise use, a telephone exchange is often referred to as a private branch exchange. Smaller installations might deploy a PBX or key telephone system in the office of a receptionist and this made it possible for subscribers to call each other at homes, businesses, or public spaces. These made telephony an available and comfortable communication tool for everyday use, one of the first to propose a telephone exchange was Hungarian Tivadar Puskás in 1877 while he was working for Thomas Edison. The first experimental telephone exchange was based on the ideas of Puskás, the worlds first commercial telephone exchange opened on November 12,1877 in Friedrichsberg close to Berlin. George W. Coy designed and built the first commercial US telephone exchange opened in New Haven. The switchboard was built from carriage bolts, handles from teapot lids and bustle wire, Charles Glidden is also credited with establishing an exchange in Lowell, MA. with 50 subscribers in 1878. In Europe other early telephone exchanges were based in London and Manchester, Belgium had its first International Bell exchange a year later. In 1887 Puskás introduced the multiplex switchboard, later exchanges consisted of one to several hundred plug boards staffed by switchboard operators. Each operator sat in front of a panel containing banks of ¼-inch tip-ring-sleeve jacks. In front of the jack panel lay a horizontal panel containing two rows of patch cords, each connected to a cord circuit. When a calling party lifted the receiver, the loop current lit a signal lamp near the jack. The operator responded by inserting the rear cord into the jack and switched her headset into the circuit to ask, Number. For a local call, the operator inserted the front cord of the pair into the partys local jack
7.
Fiber-optic communication
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Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms a carrier wave that is modulated to carry information. Fiber is preferred over electrical cabling when high bandwidth, long distance, optical fiber is used by many telecommunications companies to transmit telephone signals, Internet communication, and cable television signals. Researchers at Bell Labs have reached speeds of over 100 petabit×kilometer per second using fiber-optic communication. First developed in the 1970s, fiber-optics have revolutionized the industry and have played a major role in the advent of the Information Age. Because of its advantages over electrical transmission, optical fibers have largely replaced copper wire communications in core networks in the developed world, due to much lower attenuation and interference, optical fiber has large advantages over existing copper wire in long-distance and high-demand applications. However, infrastructure development within cities was difficult and time-consuming. Since 2000, the prices for fiber-optic communications have dropped considerably, the price for rolling out fiber to the home has currently become more cost-effective than that of rolling out a copper based network. Prices have dropped to $850 per subscriber in the US and lower in countries like The Netherlands, since 1990, when optical-amplification systems became commercially available, the telecommunications industry has laid a vast network of intercity and transoceanic fiber communication lines. Bell considered it his most important invention, the device allowed for the transmission of sound on a beam of light. On June 3,1880, Bell conducted the worlds first wireless transmission between two buildings, some 213 meters apart. Due to its use of a transmission medium, the Photophone would not prove practical until advances in laser. The Photophones first practical use came in military communication systems many decades later, in 1954 Harold Hopkins and Narinder Singh Kapany showed that rolled fiber glass allowed light to be transmitted. Initially it was considered that the light can traverse in only straight medium, after a period of research starting from 1975, the first commercial fiber-optic communications system was developed, which operated at a wavelength around 0.8 µm and used GaAs semiconductor lasers. This first-generation system operated at a bit rate of 45 Mbit/s with repeater spacing of up to 10 km, soon on 22 April 1977, General Telephone and Electronics sent the first live telephone traffic through fiber optics at a 6 Mbit/s throughput in Long Beach, California. The second generation of fiber-optic communication was developed for use in the early 1980s, operated at 1.3 µm. In 1984, they had developed a fiber optic cable that would help further their progress toward making fiber optic cables that would circle the globe. Canadian service provider SaskTel had completed construction of what was then the world’s longest commercial fiberoptic network, by 1987, these systems were operating at bit rates of up to 1.7 Gb/s with repeater spacing up to 50 km
8.
Duplex (telecommunications)
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A duplex communication system requires a pair of channels/frequencies hence the term duplex meaning two parts. The two channels are defined as uplink/downlink or reverse/forward, in a full-duplex system simultaneous transmission/reception is available, i. e. One can transmit and receive simultaneously, in a half-duplex system, each party can communicate with the other but not simultaneously, the communication is one direction at a time. Half duplex systems utilize separate channels for uplink and downlink, i. e. a transmit, in a half duplex communications system one user is allowed to transmit on the uplink channel at a time. The transmitted uplink signal is frequency translated via a radio/repeater to the downlink receive frequency which is received by all other radios tuned to the downlink/receive frequency. A half-duplex system is defined as system which operates two, hence duplex, dedicated uplink/downlink channels/frequencies. In a half duplex system a single path is provided for uplink, all uplink messages are broadcast via the downlink channel to all users simultaneously via a repeater which performs uplink to downlink channel/frequency translation. All cellular and land line PSTNs and PDSNs are full duplex systems, all full duplex systems require a channel/frequency translator via a radio/repeater. This is required in order to translate the uplink/transmit transmission from one to the downlink/receive channel/frequency of user two. Full duplex systems are one to one private systems unlike half duplex systems which broadcast to all users and this effectively makes the cable itself a collision-free environment and doubles the maximum total transmission capacity supported by each Ethernet connection. Time-division duplexing is commonly referred to as simplex communications, a single channel/frequency is employed for bidirectional communications. The term simplex communication as applied to TDM single channel systems predates the term TDD by at least 80 years, frequency-division duplexing as with any other duplex system is defined by two channel/frequency simultaneous communication. A channel/frequency pair are assigned to individual user on the system. An FDD system requires frequency translation from user 1 uplink/reverse frequency to user 2 downlink/forward frequency, full-duplex audio systems like telephones can create echo, which needs to be removed. Echo occurs when the coming out of the speaker, originating from the far end. The sound then reappears at the source end, but delayed. This feedback path may be acoustic, through the air, or it may be mechanically coupled, echo cancellation is a signal-processing operation that subtracts the far-end signal from the microphone signal before it is sent back over the network. Echo cancellation is important to the V.32, V.34, V.56, echo cancelers are available as both software and hardware implementations
9.
Tip and ring
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Tip and ring are the names of the two conductors or sides of a telephone line. The terms originate in reference to the telephone used for connecting telephone calls in manual switchboards. One side of the line is connected to the tip of the plug. When inserted into a jack, the tip conductor connects first. In many European countries tip and ring are referred to as the A and B wires, the ring conductor has a direct current potential of −48V to −52V with respect to tip conductor when the line is in the on-hook state. Neither conductor is referenced to ground, floating both conductors minimizes the pickup of hum from any nearby alternating current power wires. The terms tip and ring originated in the days of telephony when telephone operators used plugs to connect customer calls. They are named after the parts of the plug to which the wires were connected, the words are often abbreviated as T and R. The telephone company maintains large battery systems that supply DC line voltage for the operation of analog telephone service at customer locations, the voltage supplied is a compromise between operational needs for reliable service and safety precautions for customers and service personnel. The length of the line to a telephone interface presents a resistance across which the central office voltage experiences a drop. The nominal battery voltage is 52.1 V, based on a 24-cell lead-acid battery, the voltage at a subscribers network interface is typically 48 V. In the middle 20th century, long loops in many areas of North America used range extenders. Some rural switching systems were designed to apply range extenders internally and thus share a few extenders among many lines, while for other lines, originally, the potentials on the wires were positive with respect to earth. Telephone companies discovered that with positive voltage on the copper wires, operating in reverse, with a negative potential on the wires, the copper is protected from corrosion by cathodic protection. To ring the telephone to alert a subscriber to an incoming call, historically a variety of frequencies have been used, however. When Touch-Tone service was introduced in the 1960s, the dual-tone multi-frequency signaling tone generator also required correct polarity as it depended on the power for operation. Later Touch-Tone telephones included a bridge that eliminated the polarity sensitivity. When simple on-premises wiring is color-coded, two-wire telephone plugs or the first pair of a connector commonly have the tip wire coded green
10.
Volt
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The volt is the derived unit for electric potential, electric potential difference, and electromotive force. One volt is defined as the difference in potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points. It is also equal to the difference between two parallel, infinite planes spaced 1 meter apart that create an electric field of 1 newton per coulomb. Additionally, it is the difference between two points that will impart one joule of energy per coulomb of charge that passes through it. It can also be expressed as amperes times ohms, watts per ampere, or joules per coulomb, for the Josephson constant, KJ = 2e/h, the conventional value KJ-90 is used, K J-90 =0.4835979 GHz μ V. This standard is typically realized using an array of several thousand or tens of thousands of junctions. Empirically, several experiments have shown that the method is independent of device design, material, measurement setup, etc. in the water-flow analogy sometimes used to explain electric circuits by comparing them with water-filled pipes, voltage is likened to difference in water pressure. Current is proportional to the diameter of the pipe or the amount of water flowing at that pressure. A resistor would be a reduced diameter somewhere in the piping, the relationship between voltage and current is defined by Ohms Law. Ohms Law is analogous to the Hagen–Poiseuille equation, as both are linear models relating flux and potential in their respective systems, the voltage produced by each electrochemical cell in a battery is determined by the chemistry of that cell. Cells can be combined in series for multiples of that voltage, mechanical generators can usually be constructed to any voltage in a range of feasibility. High-voltage electric power lines,110 kV and up Lightning, Varies greatly. Volta had determined that the most effective pair of metals to produce electricity was zinc. In 1861, Latimer Clark and Sir Charles Bright coined the name volt for the unit of resistance, by 1873, the British Association for the Advancement of Science had defined the volt, ohm, and farad. In 1881, the International Electrical Congress, now the International Electrotechnical Commission and they made the volt equal to 108 cgs units of voltage, the cgs system at the time being the customary system of units in science. At that time, the volt was defined as the difference across a conductor when a current of one ampere dissipates one watt of power. The international volt was defined in 1893 as 1/1.434 of the emf of a Clark cell and this definition was abandoned in 1908 in favor of a definition based on the international ohm and international ampere until the entire set of reproducible units was abandoned in 1948. Prior to the development of the Josephson junction voltage standard, the volt was maintained in laboratories using specially constructed batteries called standard cells
11.
Ohm
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The ohm is the SI derived unit of electrical resistance, named after German physicist Georg Simon Ohm. The definition of the ohm was revised several times, today the definition of the ohm is expressed from the quantum Hall effect. In many cases the resistance of a conductor in ohms is approximately constant within a range of voltages, temperatures. In alternating current circuits, electrical impedance is also measured in ohms, the siemens is the SI derived unit of electric conductance and admittance, also known as the mho, it is the reciprocal of resistance in ohms. The power dissipated by a resistor may be calculated from its resistance, non-linear resistors have a value that may vary depending on the applied voltage. The rapid rise of electrotechnology in the last half of the 19th century created a demand for a rational, coherent, consistent, telegraphers and other early users of electricity in the 19th century needed a practical standard unit of measurement for resistance. Two different methods of establishing a system of units can be chosen. Various artifacts, such as a length of wire or a standard cell, could be specified as producing defined quantities for resistance, voltage. This latter method ensures coherence with the units of energy, defining a unit for resistance that is coherent with units of energy and time in effect also requires defining units for potential and current. Some early definitions of a unit of resistance, for example, the absolute-units system related magnetic and electrostatic quantities to metric base units of mass, time, and length. These units had the advantage of simplifying the equations used in the solution of electromagnetic problems. However, the CGS units turned out to have impractical sizes for practical measurements, various artifact standards were proposed as the definition of the unit of resistance. In 1860 Werner Siemens published a suggestion for a reproducible resistance standard in Poggendorffs Annalen der Physik und Chemie and he proposed a column of pure mercury, of one square millimetre cross section, one metre long, Siemens mercury unit. However, this unit was not coherent with other units, one proposal was to devise a unit based on a mercury column that would be coherent – in effect, adjusting the length to make the resistance one ohm. Not all users of units had the resources to carry out experiments to the required precision. The BAAS in 1861 appointed a committee including Maxwell and Thomson to report upon Standards of Electrical Resistance, in the third report of the committee,1864, the resistance unit is referred to as B. A. unit, or Ohmad. By 1867 the unit is referred to as simply Ohm, the B. A. ohm was intended to be 109 CGS units but owing to an error in calculations the definition was 1. 3% too small. The error was significant for preparation of working standards, on September 21,1881 the Congrès internationale délectriciens defined a practical unit of Ohm for the resistance, based on CGS units, using a mercury column at zero deg
12.
Voicemail
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The term is also used more broadly to denote any system of conveying a stored telecommunications voice messages, including using an answering machine. The term Voicemail was coined by Televoice International for their introduction of the first US-wide Voicemail service in 1980, although VMI trademarked the term, it eventually became a generic term used for referring to virtually all automated voice services employing a telephone. They became popular in the early 1980s when they were available on PC-based boards. In September 2012 a report from USA Today and Vonage claimed that Voice mail was in decline, the report said that the number of voicemail messages declined 8 percent compared to 2011. Voicemail systems are designed to convey a callers recorded audio message to a recipient, most systems use phone networks, either cellular- or landline-based, as the conduit for all of these functions. Some systems may use multiple methods, permitting recipients and callers to retrieve or leave messages through multiple methods such as PCs, PDA. Simple voicemail systems function as an answering machine using touch-tones as the user interface. More complicated systems may use other input such as voice or a computer interface. Almost all modern systems use digital storage and are typically stored on computer data storage. Notification methods also based on the voice-mail system. Simple systems may not provide active notification at all, instead requiring the recipient to check with the system, the conventional solution to efficient handling of telephone communication in businesses was the message center. A message center or message desk was a centralized, manual answering service inside a company staffed by a few operators who answered all incoming phone calls, extensions that were busy or rang no answer would forward to the message center using a device called a call director. The call director had a button for each extension in the company which would flash when that persons extension forwarded to the message center, a little label next to the button told the operator the person being called. While it was an improvement over basic multi-line systems, the center had many disadvantages. Many calls would come in simultaneously at peak periods, such as lunch time and this left message attendants with little time to take each message accurately. Often, they were not familiar with names and buzzwords. Tape-based telephone answering machines had come into the telephone market. Further, the manufacturers of PBXs used proprietary digital phone sets in order to increase the functionality and these phone sets were, by design, incompatible with answering machines
13.
Caller ID
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Caller ID may be used by the recipient to avoid answering unwanted incoming calls by the concept of informed consent. However, it also poses problems for personal privacy, usually, the caller can disable or block the Caller ID facility, but some call capture technology can bypass a caller block. On the other hand, the possibility of caller ID spoofing may render received information unreliable, with appropriate hardware, networking and software, Caller ID can also be associated with a name of the calling telephone number. The information made available to the party may be displayed on a telephones display, on a separately attached device. However, many modems are designed and programmed to handle multiple signalling methods, the idea of CNID as a service for POTS subscribers originated from automatic number identification as a part of toll free number service in the United States. However, CNID and ANI are not the same thing, ANI was originally a term given to a system that identified the telephone number placing a call, in a non-electronic central office switch. Previous to this, the number could not be identified electronically. Caller ID is made up of two pieces of information, the calling number and the billing name where available. When a call is made from a name, this name can be passed on through a number of different methods. For example, the name may be datafilled in the originating switch. More commonly, a database is accessed by the receiving switch, if the name does not exist, then the city, State, Province, or other designation may be sent. Some of these databases may be shared among several companies, each paying every time a name is extracted and it is for this reason that mobile phone callers appear as WIRELESS CALLER, or the location where the phone number is registered. Additionally, nothing ensures that the number sent by a switch is the actual number where the call originated, as such, the telephone switch, and therefore the operating entity, must also be trusted to provide secure authentication. The displayed caller ID also depends on the equipment originating the call, if the call originates on a POTS line, then caller ID is provided by the service providers local switch. Since the network does not connect the caller to the callee until the phone is answered, most service providers however, allow the caller to block caller ID presentation through the vertical service code *67. A call placed behind a branch exchange has more options. In the typical telephony environment, a PBX connects to the service provider through Primary Rate Interface trunks. Generally, although not absolutely, the service provider simply passes whatever calling line ID appears on those PRI access trunks transparently across the Public Switched Telephone Network and this opens up the opportunity for the PBX administrator to program whatever number they choose in their external phone number fields
14.
Abbreviated dialing
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Abbreviated dialing is the use of a very short digit sequence to reach specific telephone numbers, such as those of public services. The purpose of numbers is to be universal, short. Typically they are two or three digits, carriers refer to the shortened number sequences as abbreviated dialing codes. Unlike SMS shortcodes, they are not automatically synchronized across carriers. ADCs are provisioned separately for mobile networks versus landline networks, the most commonly known examples are emergency telephone numbers such as 9-9-9, 1-1-2 and 9-1-1. Other services may also be available through abbreviated dialing numbers, such as the other of the eight N11 codes of the North American Numbering Plan besides 9-1-1. State highway departments in recent years have used abbreviated dialing codes to allow drivers to obtain information about conditions or to reach the state highway patrol. Examples are *55 in Missouri and Oklahoma, or *FHP which connects to the Florida Highway Patrol, for text messaging, the technical equivalent is a short code, however these are rented by their private users rather than being universal and for public services. Vertical service codes may also be considered as abbreviated dialing, though these prefix the special touch-tone characters * and # instead of using only numerals, most are used to access calling features rather than a called party, and some are specific to each telephone company. Some are used locally or regionally, other codes as short as one numeral are used to report breaking news or traffic to the newsrooms of local news radio or TV stations. A mobile dial code is a number, typically preceded by a * or #. MDCs are also known in carrier terminology as abbreviated dialing codes, mobile dial codes are dialed just like a regular telephone number. The caller can be presented with any one of a variety of responses that an advertiser defines - a voice or IVR call, a message, a video or audio clip. #250 and **MOVE are two such MDCs. com
15.
Conference call
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A conference call is a telephone call in which someone talks to several people at the same time. The conference calls may be designed to allow the party to participate during the call, or the call may be set up so that the called party merely listens into the call. The more limited three-way calling is available on home or office phone lines, for a three-way call, the first called party is dialed. Then the hook flash button is pressed and the called partys phone number is dialed. While it is ringing, flash/recall is pressed again to connect the three people together and this option allows callers to add a second outgoing call to an already connected call. Businesses use conference calls daily to meet with remote parties, both internally and outside of their company, common applications are client meetings or sales presentations, project meetings and updates, regular team meetings, training classes and communication to employees who work in different locations. Conference calling is viewed as a means of cutting travel costs. Conference calls are used by nearly all United States public corporations to report their quarterly results and these calls usually allow for questions from stock analysts and are called earnings calls. A standard conference call begins with a disclaimer stating that anything said in the duration of the call may be a statement. The CEO, CFO, or investor relations officer then read the companys quarterly report. Lastly, the call is opened for questions from analysts, conference calls are increasingly used in conjunction with web conferences, where presentations or documents are shared via the internet. This allows people on the call to view content such as reports, sales figures. The main benefit is that the presenter of the document can give clear explanations about details within the document, care should also be taken to schedule a call at a convenient time. Business conference calls are usually hosted or operator-assisted, with a variety of features, conference calls are also beginning to cross over into the world of podcasting and social networking, which in turn fosters new kinds of interaction patterns. Live streaming or broadcasting of conference calls allows a larger access to the call without dialing in to a bridge. In addition, organizers of conference calls can publish a dial-in number alongside the stream, creating potential for audience members to dial in. The UK government has changed flexible working rights since 2014 so that employees who have been working full-time for a company or organisation can lawfully request flexible working. In recent years, there has been a number of different types of flexible working options as a result of conference calling technology enabling employees to work remotely, flat-rate conferencing services are being offered which give unlimited access to a conference bridge at a fixed monthly cost
16.
Enhanced 9-1-1
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Enhanced 911, E-911 or E911 is a system used in North America that links emergency callers with the appropriate public resources. Three-digit emergency telephone numbers originated in the United Kingdom in 1937 and have spread to continents, other easy dial codes, including the 112 number adopted by the European Union in 1991, have been deployed to provide free-of-charge emergency calls. In North America, where 9-1-1 was chosen as the access code. This location may be an address or other geographic reference information such as X/Y map coordinates. The callers telephone number is used in numerous manners to track a location that can be used to police, fire, emergency medical. In North America the incoming 9-1-1 call is answered at the Public Safety Answering Point of the governmental agency that has jurisdiction over the callers location. When the 9-1-1 call arrives at the appropriate PSAP, it is answered by a trained official known as a Telecommunicator. In some jurisdictions the Telecommunicator is also the dispatcher of public safety response resources, when a landline call arrives at the PSAP, special computer software uses the telephone number to retrieve and display the location of the caller in near real-time upon arrival of the call. The system only works in North America if the telephone number 911 is called. Calls made to other numbers, even though they may be listed as an emergency telephone number. Outside Canada, Mexico, and the United States this type of facility is called caller location. The first 911 system was installed in Haleyville, Alabama, in February 1968, the system was rapidly adapted and improved by other telephone companies, evolving into the E911 system, which provides both caller location and identification. A pioneering system was in place in Chicago by the mid-1970s, Enhanced 911 is currently deployed in most metropolitan areas in the United States, Canada, and Mexico as well as all of the Cayman Islands. Location is an important concept in the manner of how the Enhanced 9-1-1 system works, often, the contracted 3rd party further subcontracts the actual ALI database management to companies such as Intrado, Bandwidth and TeleCommunication Systems, Inc. When the call is delivered to the PSAP, a query is made to the Automatic Location Information. There is a difference between the location is determined for different types of calls based upon the type of originating device or network. For each of these categories please see the sections below for the categories to learn more about location determination for each of the following types of calls. There are hardwired or Wireline enhanced 911 calls which originate from a device connected to a fixed point of connection to the PSTN
17.
Pulse dialing
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This lends the method the often used name loop disconnect dialing. In the most common variant of pulse dialing, decadic dialing, 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 dial of the telephone, lending the technology another name. The pulse repetition rate was determined based on the response time needed for electromechanical switching systems to operate reliably. Most telephone systems used the nominal rate of ten pulses per second, automatic telephone exchange systems were developed in the late 19th and early 20th century. For identification, telephone subscribers were assigned a number unique to each circuit. Various methods evolved to signal the desired destination telephone number for a telephone call directly dialed by the subscriber, an automatic switch-hook was designed by Hilborne Roosevelt. But the use of keys with separate conductors to the exchange was not practical. Strowger also filed the first patent for a dial in 1891. The first dials worked by direct, forward action, the pulses were sent as the user rotated the dial to the finger stop starting at a different position for each digit transmitted. Operating the dial error-free required smooth rotary motion of the wheel by the user. This mechanism was soon refined to include a spring and a centrifugal governor to control the recoil speed. The user selected a digit to be dialed by inserting a finger into the corresponding hole, when released from this position, the dial pulsing contacts were opened and closed repeatedly, thus interrupting the loop current in a pattern on the return to the home position. The exchange switch decoded the pattern for each digit thus transmitted by stepping relays or by accumulation in digit registers. When electromechanical switching system were still in use, the current pulses generated by the dial on the local loop operated electrical relays in the switches at the central office. The mechanical nature of these relays and the capacitance, affecting pulse shape, generally limited the speed of operation. Exceptions to this are, Sweden, with one click for 0, two clicks for 1, and so on, and New Zealand with ten clicks for 0, nine clicks for 1, etc. Oslo, the city of Norway, used the New Zealand system
18.
Modem
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A modem is a network hardware device that modulates one or more carrier wave signals to encode digital information for transmission and demodulates signals to decode the transmitted information. The goal is attempting to produce a signal that can be transmitted easily, modems can be used with any means of transmitting analog signals, from light emitting diodes to radio. Modems are generally classified by the amount of data they can send in a given unit of time, usually expressed in bits per second. Modems can also be classified by their rate, measured in baud. The baud unit denotes symbols per second, or the number of times per second the modem sends a new signal. For example, the ITU V.21 standard used audio frequency shift keying with two frequencies, corresponding to two distinct symbols, to carry 300 bits per second using 300 baud. By contrast, the original ITU V.22 standard, which could transmit and receive four distinct symbols, news wire services in the 1920s used multiplex devices that satisfied the definition of a modem. However, the function was incidental to the multiplexing function, so they are not commonly included in the history of modems. S. SAGE modems were described by AT&Ts Bell Labs as conforming to their newly published Bell 101 dataset standard, while they ran on dedicated telephone lines, the devices at each end were no different from commercial acoustically coupled Bell 101,110 baud modems. The 201A and 201B Data-Phones were synchronous modems using two-bit-per-baud phase-shift keying, the famous Bell 103A dataset standard was also introduced by AT&T in 1962. It provided full-duplex service at 300 bit/s over normal phone lines, frequency-shift keying was used, with the call originator transmitting at 1,070 or 1,270 Hz and the answering modem transmitting at 2,025 or 2,225 Hz. The readily available 103A2 gave an important boost to the use of remote low-speed terminals such as the Teletype Model 33 ASR and KSR, AT&T reduced modem costs by introducing the originate-only 113D and the answer-only 113B/C modems. For many years, the Bell System maintained a monopoly on the use of its phone lines, however, the seminal Hush-a-Phone v. FCC case of 1956 concluded it was within the FCCs jurisdiction to regulate the operation of the Bell System. The FCC found that as long as a device was not electronically attached to the system and this led to a number of devices that mechanically connected to the phone through a standard handset. Since most handsets were supplied by Western Electric and thus of a standard design and this type of connection was used for many devices, such as answering machines. Acoustically coupled Bell 103A-compatible 300 bit/s modems were common during the 1970s, well-known models included the Novation CAT and the Anderson-Jacobson, the latter spun off from an in-house project at Stanford Research Institute. An even lower-cost option was the Pennywhistle modem, designed to be built using parts from electronics scrap, in December 1972, Vadic introduced the VA3400, notable for full-duplex operation at 1,200 bit/s over the phone network. Like the 103A, it used different frequency bands for transmit, in November 1976, AT&T introduced the 212A modem to compete with Vadic
19.
Fax
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Fax, sometimes called telecopying or telefax, is the telephonic transmission of scanned printed material, normally to a telephone number connected to a printer or other output device. The receiving fax machine interprets the tones and reconstructs the image, early systems used direct conversions of image darkness to audio tone in a continuous or analog manner. Since the 1980s, most machines modulate the audio frequencies using a digital representation of the page which is compressed to quickly transmit areas which are all-white or all-black. Scottish inventor Alexander Bain worked on chemical mechanical fax type devices and he received British patent 9745 on May 27,1843 for his Electric Printing Telegraph. Frederick Bakewell made several improvements on Bains design and demonstrated a telefax machine, the Pantelegraph was invented by the Italian physicist Giovanni Caselli. He introduced the first commercial service between Paris and Lyon in 1865, some 11 years before the invention of the telephone. In 1880, English inventor Shelford Bidwell constructed the scanning phototelegraph that was the first telefax machine to scan any two-dimensional original, previously, photographs had been sent over the radio using this process. The Western Union Deskfax fax machine, announced in 1948, was a machine that fit comfortably on a desktop. As a designer for the Radio Corporation of America, in 1924, Richard H. Ranger invented the wireless photoradiogram, or transoceanic radio facsimile, the forerunner of today’s fax machines. A photograph of President Calvin Coolidge sent from New York to London on November 29,1924 became the first photo picture reproduced by transoceanic radio facsimile, commercial use of Ranger’s product began two years later. Also in 1924, Herbert E. Ives of AT&T Corporation transmitted and reconstructed the first color facsimile, around 1952 or so, Finch Facsimile, a highly developed machine, was described in detail in a book, it was never manufactured in quantity. By the late 1940s, radiofax receivers were sufficiently miniaturized to be fitted beneath the dashboard of Western Unions Telecar telegram delivery vehicles, in the 1960s, the United States Army transmitted the first photograph via satellite facsimile to Puerto Rico from the Deal Test Site using the Courier satellite. Radio fax is still in limited use today for transmitting weather charts, in 1964, Xerox Corporation introduced what many consider to be the first commercialized version of the modern fax machine, under the name or Long Distance Xerography. This model was superseded two years later with a unit that would set the standard for fax machines for years to come. Up until this point facsimile machines were expensive and hard to operate. In 1966, Xerox released the Magnafax Telecopiers, a smaller and this unit was far easier to operate and could be connected to any standard telephone line. This machine was capable of transmitting a letter-sized document in about six minutes, the first sub-minute, digital fax machine was developed by Dacom, which built on digital data compression technology originally developed at Lockheed for satellite communication. By the late 1970s, many companies around the world, entered the fax market, very shortly after a new wave of more compact, faster and efficient fax machines would hit the market
20.
Bandwidth (signal processing)
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Bandwidth is the difference between the upper and lower frequencies in a continuous set of frequencies. It is typically measured in hertz, and may refer to passband bandwidth, sometimes to baseband bandwidth. Passband bandwidth is the difference between the upper and lower frequencies of, for example, a band-pass filter, a communication channel. In the case of a filter or baseband signal, the bandwidth is equal to its upper cutoff frequency. A key characteristic of bandwidth is that any band of a given width can carry the amount of information. For example, a 3 kHz band can carry a telephone conversation whether that band is at baseband or modulated to some higher frequency, Bandwidth is a key concept in many telecommunications applications. In radio communications, for example, bandwidth is the range occupied by a modulated carrier signal. An FM radio receivers tuner spans a range of frequencies. A government agency may apportion the regionally available bandwidth to broadcast license holders so that their signals do not mutually interfere, each transmitter owns a slice of bandwidth. For different applications there are different precise definitions, which are different for signals than for systems. One definition of bandwidth, for a system, could be the range of frequencies over which the system produces a level of performance. A less strict and more practically useful definition will refer to the frequencies beyond which frequency response is small, small could mean less than 3 dB below the maximum value, or more rarely 10 dB below, or it could mean below a certain absolute value. As with any definition of the width of a function, many definitions are suitable for different purposes, in some contexts, the signal bandwidth in hertz refers to the frequency range in which the signals spectral density is nonzero or above a small threshold value. That definition is used in calculations of the lowest sampling rate that will satisfy the sampling theorem, the threshold value is often defined relative to the maximum value, and is most commonly the 3dB point, that is the point where the spectral density is half its maximum value. The word bandwidth applies to signals as described above, but it could apply to systems. To say that a system has a certain bandwidth means that the system can process signals of that bandwidth, or that the system reduces the bandwidth of a white noise input to that bandwidth. If the maximum gain is 0 dB, the 3 dB bandwidth is the range where the gain is more than −3 dB. This is also the range of frequencies where the gain is above 70. 7% of the maximum amplitude gain
21.
25-pair color code
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The 25-pair color code is a color code used to identify individual conductors in twisted-pair wiring for telecommunications. The colors are applied to the insulation that covers each conductor, the first color is chosen from one group of 5 colors and the other color from a second group of 5 colors, giving 25 combinations of two colors. The code is seen in RJ21 cables. The first group of colors is, in order, white, red, black, yellow, the second group of colors is, in order, blue, orange, green, brown, slate. The 25 combinations are shown to the right in the image, the combinations are also shown in the table below showing the color for each wire and the pair number. In addition to the number, the pairs may also be referred to by their color codes as the major/minor or major-minor pair. The first five combinations are common in telecommunications and data wiring worldwide. The color violet is sometimes called purple, but in the telecommunications, similarly, slate is a particular shade of gray. The names of most of the colors were taken from the colors of the rainbow or optical spectrum, and in the electronic color code. Usually, each wire in a pair will have a stripe, dots. This makes it easy to identify which pair a given wire belongs to and this means that the first pair is a mate of white with a blue tracer and a colour wire of blue with a white tracer. Pair 17 would be a mate of yellow with an orange tracer, neither of these two wires has any connection to the local ground. This creates an audio circuit with common-mode rejection also known as a differential pair. This convention works in the UK with the first or mate wire as the positive A leg, the connection furthest from the cable is known as the tip, the middle connection is the ring, and the connection closest to the wire is the sleeve. The pattern then starts over with the first 25 pair group as white/blue, and continues indefinitely, in multiples of 600 pairs or parts thereof. For example, a 900-pair cable will have the first 600 pairs in 24 groups of 25 pairs in a binder. Some cables are mirrored or clocked with a pattern that is throughout the telephone industry. Starting with the first binder group in the center, the technician counts the cables groups in a direction depending on the location of the Central Office or switch
22.
Managed facilities-based voice network
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MFVNs are interconnected with the public switched telephone network and provide dialtone to end users. MFVN providers include cable operators and telephone companies, but do not include Internet based providers such as Vonage, Magic Jack, the term MFVN was introduced in 2007 by various telephony user organizations and stakeholders who rely on telephone service to provide security and life safety services. The concern of these organizations and stakeholders was the reliability of new telephone technology and this new technology was based on packet voice technology, or the Voice over Internet Protocol, which was not well understood. Clear performance requirements were needed to define when a line was suitable for security. This issue was not new, as analog copper based networks had been transitioning to digital technology for 25 years. What was new was that copper based analog phone service was not even an option anymore in many areas, as it was being replaced by digital. Starting in the part of the 2000s, IP based voice services began being offered by non-traditional providers such as cable television service providers. The demand for services grew due to competitive pricing and value added services not offered by the traditional telephone providers. The use of these non-traditional telephone methods for security and life safety communications was not well understood, so use was discouraged, there was no distinction between voice services provided over the best-effort Internet and voice services provided over managed facilities. It became clear that only managed facilities based providers could assure reliability end to end, only facilities based providers could monitor and maintain the expected quality of service. Local authorities, such as inspectors, now no longer need to make these determinations on an individual case basis. States have begun to recognize and accept the use of MFVN, in Florida, it has been adopted by statute, whereby all quaified MFVNs are now allowed for fire alarm monitoring. They are the non-MFVN Internet VoIP, Plain Old Telephone Service MFVN, MFVN Cable, MFVN DSL, phone Services Agreements That Support Security System Monitoring
23.
Network interface device
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In telecommunications, a network interface device is a device that serves as the demarcation point between the carriers local loop and the customers premises wiring. Outdoor telephone NIDs also provide the subscriber access to the station wiring and serve as a convenient test point for verification of loop integrity. Generically, an NID may also be called a network interface unit, telephone network interface, system network interface, australias National Broadband Network uses the term network termination device or NTD. A smartjack is a type of NID with capabilities beyond simple electrical connection, an optical network terminal is a type of NID used with fiber-to-the-premises applications. The simplest NIDs are essentially just a set of wiring terminals. These will typically take the form of a small, weather-proof box, the telephone line from the telephone company will enter the NID and be connected to one side. The customer connects their wiring to the other side, a single NID enclosure may contain termination for a single line or multiple lines. In its role as the point, the NID separates the telephone companys equipment from the customers wiring. The telephone company owns the NID itself, and all wiring up to it, anything past the NID is the customers responsibility. To facilitate this, there is typically a test jack inside the NID, accessing the test jack disconnects the customer premises wiring from the public switched telephone network and allows the customer to plug a known good telephone into the jack to isolate trouble. If the telephone works at the test jack, the problem is the wiring. If the telephone does not work, the line is faulty, most NIDs also include circuit protectors, which are surge protectors for a telephone line. They protect customer wiring, equipment, and personnel from any transient energy on the line, simple NIDs contain no digital logic, they are dumb devices. They have no capabilities beyond wiring termination, circuit protection, several types of NIDs provide more than just a terminal for the connection of wiring. Such NIDs are colloquially called smartjacks or Intelligent Network Interface Devices as an indication of their intelligence, as opposed to a simple NID. Smartjacks are typically used for more complicated types of telecommunications service, plain old telephone service lines generally cannot be equipped with smartjacks. Despite the name, most smartjacks are much more than a telephone jack. One common form for a smartjack is a circuit board with a face plate on one edge
24.
Registered jack
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A Registered Jack is a standardized telecommunication network interface for connecting voice and data equipment to a service provided by a local exchange carrier or long distance carrier. They were subsequently codified in the Code of Federal Regulations Part 68, the specification includes physical construction, wiring, and signal semantics. Accordingly, registered jacks are primarily named by the letters RJ, additionally, letter suffixes indicate minor variations. For example, RJ11, RJ14, and RJ25 are the most commonly used interfaces for telephone connections for one-, two-, although these standards are legal definitions in the United States, some interfaces are used world-wide. The connectors used for registered jack installations are primarily the modular connector, for example, RJ11 uses a six-position two-conductor connector, RJ14 uses a six-position four-conductor modular jack, while RJ21 uses a 25-pair miniature ribbon connector. The same modular connector type may be used for different registered jack applications, there is much confusion over these connection standards. The RJ11 standard dictates a single wire connection, while RJ14 is a configuration for two lines, and RJ25 uses all six wires for three telephones lines. The RJ designations, though, only pertain to the wiring of the jack, hence the name Registered Jack, it is commonplace, modular connectors were developed to replace older telephone installation methods that used either hardwired cords, or bulkier varieties of telephone plugs. The common nomenclature for modular connectors includes the number of contact positions, a six-position modular plug with conductors in the middle two positions and the other four positions unused has the designation 6P2C. The connectors could be supplied with more pins, but if more pins are actually wired and these interfaces used newly standardized jacks and plugs, primarily based on miniature modular connectors. The wired communications provider is responsible for delivery of services to a point of entry. The MPOE is a utility box, usually containing surge protective circuitry, customers are responsible for all jacks, wiring, and equipment on their side of the MPOE. The intent was to establish a standard for wiring and interfaces. In the Bell System, following the Communications Act of 1934, telephones were generally hardwired, but may have been installed with Bell System connectors to permit portability. The legal case Hush-A-Phone v. Registered jacks replaced the use of protective couplers provided exclusively by the telephone company, the new modular connectors were much smaller and cheaper to produce than the earlier, bulkier connectors that were used in the Bell System since the 1930s. The Bell System issued specifications for the connectors and their wiring as Universal Service Order Codes. USOCs are commonly specified to the communications provider by large businesses for a variety of services, because there are many standardized interface options available to the customer, the customer must specify the type of interface required by RJ/USOC. For a multi-line interface such as the RJ21, the customer must denote which position of the interface are to be used, if there are multiple RJ21 connectors, they are numbered sequentially and the customer must advise the communications provider of which one to use. TR5-1999
25.
Twisted pair
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It was invented by Alexander Graham Bell. In balanced pair operation, the two wires carry equal and opposite signals, and the destination detects the difference between the two and this is known as differential mode transmission. Noise sources introduce signals into the wires by coupling of electric or magnetic fields, the noise thus produces a common-mode signal which is canceled at the receiver when the difference signal is taken. This problem is especially apparent in telecommunication cables where pairs in the same cable lie next to each other for many miles, one pair can induce crosstalk in another and it is additive along the length of the cable. Twisting the pairs counters this effect as on each half twist the wire nearest to the noise-source is exchanged, providing the interfering source remains uniform, or nearly so, over the distance of a single twist, the induced noise will remain common-mode. Differential signaling also reduces electromagnetic radiation from the cable, along with the associated attenuation allowing for greater distance between exchanges, the twist rate makes up part of the specification for a given type of cable. When nearby pairs have equal twist rates, the conductors of the different pairs may repeatedly lie next to each other. For this reason it is specified that, at least for cables containing small numbers of pairs. In contrast to shielded or foiled twisted pair, UTP cable is not surrounded by any shielding, UTP is the primary wire type for telephone usage and is very common for computer networking, especially as patch cables or temporary network connections due to the high flexibility of the cables. The earliest telephones used telegraph lines, or open-wire single-wire earth return circuits, in the 1880s electric trams were installed in many cities, which induced noise into these circuits. Lawsuits being unavailing, the telephone companies converted to balanced circuits, as electrical power distribution became more commonplace, this measure proved inadequate. Two wires, strung on either side of cross bars on utility poles, within a few years, the growing use of electricity again brought an increase of interference, so engineers devised a method called wire transposition, to cancel out the interference. In wire transposition, the wires exchange position once every several poles, in this way, the two wires would receive similar EMI from power lines. This represented an early implementation of twisting, with a twist rate of about four twists per kilometre, such open-wire balanced lines with periodic transpositions still survive today in some rural areas. Twisted-pair cabling was invented by Alexander Graham Bell in 1881, by 1900, the entire American telephone line network was either twisted pair or open wire with transposition to guard against interference. UTP cables are found in many Ethernet networks and telephone systems, for indoor telephone applications, UTP is often grouped into sets of 25 pairs according to a standard 25-pair color code originally developed by AT&T Corporation. A typical subset of these colors shows up in most UTP cables, for urban outdoor telephone cables containing hundreds or thousands of pairs, the cable is divided into small but identical bundles. Each bundle consists of twisted pairs that have different twist rates, the bundles are in turn twisted together to make up the cable
26.
International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
27.
Telecommunication
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Telecommunication is the transmission of signs, signals, messages, writings, images and sounds or intelligence of any nature by wire, radio, optical or other electromagnetic systems. Telecommunication occurs when the exchange of information between communication participants includes the use of technology and it is transmitted either electrically over physical media, such as cables, or via electromagnetic radiation. Such transmission paths are divided into communication channels which afford the advantages of multiplexing. The term is used in its plural form, telecommunications. Early means of communicating over a distance included visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, other examples of pre-modern long-distance communication included audio messages such as coded drumbeats, lung-blown horns, and loud whistles. Zworykin, John Logie Baird and Philo Farnsworth, the word telecommunication is a compound of the Greek prefix tele, meaning distant, far off, or afar, and the Latin communicare, meaning to share. Its modern use is adapted from the French, because its use was recorded in 1904 by the French engineer. Communication was first used as an English word in the late 14th century, in the Middle Ages, chains of beacons were commonly used on hilltops as a means of relaying a signal. Beacon chains suffered the drawback that they could pass a single bit of information. One notable instance of their use was during the Spanish Armada, in 1792, Claude Chappe, a French engineer, built the first fixed visual telegraphy system between Lille and Paris. However semaphore suffered from the need for skilled operators and expensive towers at intervals of ten to thirty kilometres, as a result of competition from the electrical telegraph, the last commercial line was abandoned in 1880. Homing pigeons have occasionally used throughout history by different cultures. Pigeon post is thought to have Persians roots and was used by the Romans to aid their military, frontinus said that Julius Caesar used pigeons as messengers in his conquest of Gaul. The Greeks also conveyed the names of the victors at the Olympic Games to various cities using homing pigeons, in the early 19th century, the Dutch government used the system in Java and Sumatra. And in 1849, Paul Julius Reuter started a service to fly stock prices between Aachen and Brussels, a service that operated for a year until the gap in the telegraph link was closed. Sir Charles Wheatstone and Sir William Fothergill Cooke invented the telegraph in 1837. Also, the first commercial electrical telegraph is purported to have constructed by Wheatstone and Cooke. Both inventors viewed their device as an improvement to the electromagnetic telegraph not as a new device, samuel Morse independently developed a version of the electrical telegraph that he unsuccessfully demonstrated on 2 September 1837
28.
History of telecommunication
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The history of telecommunication began with the use of smoke signals and drums in Africa, the Americas and parts of Asia. In the 1790s, the first fixed semaphore systems emerged in Europe and this article details the history of telecommunication and the individuals who helped make telecommunication systems what they are today. The history of telecommunication is an important part of the history of communication. Early telecommunications included smoke signals and drums, talking drums were used by natives in Africa, New Guinea and South America, and smoke signals in North America and China. Contrary to what one might think, these systems were used to do more than merely announce the presence of a military camp. In Rabbinical Judaism a signal was given by means of kerchiefs or flags at intervals along the way back to the high priest to indicate the goat for Azazel had been pushed from the cliff, greek hydraulic semaphore systems were used as early as the 4th century BC. The hydraulic semaphores, which worked with water filled vessels and visual signals, however, they could only utilize a very limited range of pre-determined messages, and as with all such optical telegraphs could only be deployed during good visibility conditions. During the Middle Ages, chains of beacons were used on hilltops as a means of relaying a signal. Beacon chains suffered the drawback that they could pass a single bit of information. One notable instance of their use was during the Spanish Armada, french engineer Claude Chappe began working on visual telegraphy in 1790, using pairs of clocks whose hands pointed at different symbols. These did not prove quite viable at long distances, and Chappe revised his model to use two sets of jointed wooden beams, operators moved the beams using cranks and wires. He built his first telegraph line between Lille and Paris, followed by a line from Strasbourg to Paris, in 1794, a Swedish engineer, Abraham Edelcrantz built a quite different system from Stockholm to Drottningholm. As opposed to Chappes system which involved pulleys rotating beams of wood, however semaphore as a communication system suffered from the need for skilled operators and expensive towers often at intervals of only ten to thirty kilometres. As a result, the last commercial line was abandoned in 1880, experiments on communication with electricity, initially unsuccessful, started in about 1726. Scientists including Laplace, Ampère, and Gauss were involved, both their designs employed multiple wires in order to visually represent almost all Latin letters and numerals. Thus, messages could be conveyed electrically up to a few kilometers, the telegraph receivers operator would visually observe the bubbles and could then record the transmitted message, albeit at a very low baud rate. The first working telegraph was built by Francis Ronalds in 1816, Charles Wheatstone and William Fothergill Cooke patented a five-needle, six-wire system, which entered commercial use in 1838. It used the deflection of needles to represent messages and started operating over twenty-one kilometres of the Great Western Railway on 9 April 1839, both Wheatstone and Cooke viewed their device as an improvement to the electromagnetic telegraph not as a new device
29.
Beacon
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A beacon is an intentionally conspicuous device designed to attract attention to a specific location. When used in fashion, beacons can be considered a form of optical telegraphy. Beacons help guide navigators to their destinations, types of navigational beacons include radar reflectors, radio beacons, sonic and visual signals. Visual beacons range from small, single-pile structures to large lighthouses or light stations, lighted beacons are called lights, unlighted beacons are called daybeacons. As signals, beacons are an ancient form of telegraph and were part of a relay league. Systems of this kind have existed for centuries over much of the world, the ancient Romans used beacons and beacons figure on several occasions on the column of Trajan. It was devised by Leo the Mathematician for Emperor Theophilos, but either abolished or radically curtailed by Theophilos son and successor, Michael III. Beacons were later used in Greece as well, while the parts of the beacon system in Anatolia seem to have been reactivated in the 12th century by Emperor Manuel I Komnenos. In Scandinavia many hill forts were part of networks to warn against invading pillagers. In Finland, these beacons were called vainovalkeat, persecution fires, or vartiotulet, guard fires, in Wales, the Brecon Beacons were named for beacons used to warn of approaching English raiders. In England, the most famous examples are the used in Elizabethan England to warn of the approaching Spanish Armada. Many hills in England were named Beacon Hill after such beacons, in the Scottish borders country, a system of beacon fires was at one time established to warn of incursions by the English. Hume and Eggerstone castles and Soltra Edge were part of this network, the Great Wall of China is also a beacon network. In Spain, the border of Granada in the territory of the Crown of Castile had a beacon network to warn against Moorish raiders. Vehicular beacons are rotating or flashing lights affixed to the top of a vehicle to attract the attention of surrounding vehicles, emergency vehicles such as fire engines, ambulances, police cars, tow trucks, construction vehicles, and snow-removal vehicles carry beacon lights. Beacons may be constructed with halogen bulbs similar to those used in vehicle headlamps, xenon flashtubes, incandescent and xenon light sources require the vehicle’s engine to continue running to ensure that the battery is not depleted when the lights are used for a prolonged period. The low power consumption of LEDs allows the engine to remain turned off while the lights operate nodes. Beacons and bonfires are used to mark occasions and celebrate events
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History of broadcasting
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The first broadcasting of a radio transmission consisted of Morse code was made from a temporary station set up by Guglielmo Marconi in 1895. This followed on from pioneering work in the field by Alessandro Volta, André-Marie Ampère, Georg Ohm, James Clerk Maxwell, the broadcasting of music and talk via radio started experimentally around 1905-1906, and commercially around 1920 to 1923. VHF stations started 30 to 35 years later, when people started broadcasting television the first movie that was shown was Batman curse of the green pearl it was 10 minutes long. In Britain this system was known as Electrophone, and was available as early as 1895 or 1899, in Hungary, it was called Telefon Hírmondó, and in France, Théâtrophone ). The Wikipedia Telefon Hírmondó page includes a 1907 program guide which looks similar to the types of schedules used by many broadcasting stations some 20 or 30 years later. By the 1950s, virtually every country had a broadcasting system, today, most countries have evolved into a dual system, including the UK. By 1955, practically every family in North America and Western Europe, a dramatic change came in the 1960s with the introduction of small inexpensive portable transistor radio, the greatly expanded ownership and usage. Access became practically universal across the world, Australia developed its own system, through its own engineers, manufacturers, retailers, newspapers, entertainment services, and news agencies. The government set up the first radio system, and business interests marginalized the hobbyists, the Labor Party was especially interested in radio because it allowed them to bypass the newspapers, which were mostly controlled by the opposition. Both parties agreed on the need for a system, and in 1932 set up the Australian Broadcasting Commission. The first commercial broadcasters, originally known as B class stations, were on the air as early as 1925, the number of stations remained relatively dormant throughout World War II and in the post-war era. The broadcasting system was deregulated in 1992, except that there were limits on foreign ownership. By 2000,99 percent of Australians owned at least one television set, Australian radio hams can be traced to the early 1900s. The 1905 Wireless Telegraphy Act whilst acknowledging the existence of wireless telgraphy, in 1906, the first official Morse code transmission in Australia was by the Marconi Company between Queenscliff, Victoria and Devonport, Tasmania. The first broadcast of music was made during a demonstration on 13 August 1919 by Ernest Fisk of AWA – Amalgamated Wireless, a number of amateurs commenced broadcasting music in 1920 and 1921. 2CM was run by Charles MacLuran who started the station in 1921 with regular Sunday evening broadcasts from the Wentworth Hotel, 2CM is often regarded as Australias first, regular, non-official station. It was not until November 1923 when the government finally gave its approval for a number of officially recognised medium wave stations, all stations operated under a unique Sealed Set system under which each set was sealed to the frequency of one station. Part of the price of the set went to the government via the Postmaster-Generals Department, apart from extremely limited advertising, this was the broadcasters only source of income
