Fax
`
`From Wikipedia, the free encyclopedia
`
`Fax (short for facsimile), sometimes called
`telecopying or telefax, is the telephonic transmission
`of scanned printed material (both text and images),
`normally to a telephone number connected to a
`printer or other output device. The original document
`is scanned with a fax machine (or a telecopier),
`which processes the contents (text or images) as a
`single fixed graphic image, converting it into a
`bitmap, and then transmitting it through the telephone
`system in the form of audio-frequency tones. The
`receiving fax machine interprets the tones and
`reconstructs the image, printing a paper copy.[1] Early
`systems used direct conversions of image darkness to
`audio tone in a continuous or analog manner. Since
`the 1980s, most machines modulate the transmitted
`audio frequencies using a digital representation of the page which is compressed to quickly transmit areas
`which are all-white or all-black.
`
`A fax machine from the late 1990s
`
`Contents
`
`◾ 1 Fax in the 21st century
`◾ 2 History
`◾ 2.1 Wire transmission
`◾ 2.2 Wireless transmission
`◾ 2.3 Telephone transmission
`◾ 2.4 Computer facsimile interface
`◾ 3 Capabilities
`◾ 3.1 Group
`◾ 3.1.1 Analog
`◾ 3.1.2 Digital
`◾ 3.2 Class
`◾ 3.3 Data transmission rate
`◾ 3.4 Compression
`◾ 3.4.1 Modified Huffman
`◾ 3.4.2 Modified READ
`◾ 3.4.3 Modified Modified READ
`◾ 3.4.4 JBIG
`◾ 3.4.5 Matsushita Whiteline Skip
`◾ 3.5 Typical characteristics
`◾ 3.6 Printing process
`◾ 3.7 Stroke speed
`
`http://en.wikipedia.org/wiki/Fax
`
`Page 1 of 12
`
`E-Watch, Inc.
`Exh. 2013
`Petitioner - HTC Corporation, et al.
`Patent Owner - E-Watch, Inc.
`IPR2014-00987/IPR2015-00541 and
`IPR2014-00989/IPR2015-00543
`
`

`

`◾ 4 Internet fax
`◾ 5 See also
`◾ 6 References
`◾ 7 Further reading
`◾ 8 External links
`
`Fax in the 21st century
`
`Although businesses usually maintain some kind of fax capability, the technology has faced increasing
`competition from Internet-based alternatives. In some countries, because electronic signatures on
`contracts are not yet recognized by law, while faxed contracts with copies of signatures are, fax machines
`enjoy continuing support in business.[2] In Japan, faxes are still used extensively for cultural and
`graphemic reasons and are available for sending to both domestic and international recipients from over
`81% of all convenience stores nationwide. Convenience-store fax machines commonly print the slightly
`re-sized content of the sent fax in the electronic confirmation-slip, in A4 paper size.[3][4][5]
`
`In many corporate environments, freestanding fax machines have been replaced by fax servers and other
`computerized systems capable of receiving and storing incoming faxes electronically, and then routing
`them to users on paper or via an email (which may be secured). Such systems have the advantage of
`reducing costs by eliminating unnecessary printouts and reducing the number of inbound analog phone
`lines needed by an office.
`
`The once ubiquitous fax machine has also begun to disappear from the small office and home office
`environments. Remotely hosted fax-server services are widely available from VoIP and e-mail providers
`allowing users to send and receive faxes using their existing e-mail accounts without the need for any
`hardware or dedicated fax lines. Personal computers have also long been able to handle incoming and
`outgoing faxes using analogue modems or ISDN, eliminating the need for a stand-alone fax machine.
`These solutions are often ideally suited for users who only very occasionally need to use fax services.
`History
`
`Wire transmission
`
`Scottish inventor Alexander Bain worked on chemical mechanical fax type devices and in 1846 was able
`to reproduce graphic signs in laboratory experiments. He received patent 9745 on May 27, 1843 for his
`"Electric Printing Telegraph."[6] Frederick Bakewell made several improvements on Bain's design and
`demonstrated a telefax machine. The Pantelegraph was invented by the Italian physicist Giovanni Caselli.
`He introduced the first commercial telefax service between Paris and Lyon in 1865, some 11 years before
`the invention of telephones.[7][8]
`
`In 1881, English inventor Shelford Bidwell constructed the scanning phototelegraph that was the first
`telefax machine to scan any two-dimensional original, not requiring manual plotting or drawing. Around
`1900, German physicist Arthur Korn invented the Bildtelegraph, widespread in continental Europe
`
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`

`

`especially, since a widely noticed transmission of a wanted-person photograph from Paris to London in
`1908, used until the wider distribution of the radiofax. Its main competitors were the Bélinographe by
`Édouard Belin first, then since the 1930s the Hellschreiber, invented in 1929 by German inventor Rudolf
`Hell, a pioneer in mechanical image scanning and transmission.
`
`The 1888 invention of the telautograph by Elisha Grey marked a further development in fax technology,
`allowing users to send signatures over long distances, thus allowing the verification of identification or
`ownership over long distances.[9]
`
`On May 19, 1924, scientists of the AT&T Corporation "by a new process of transmitting pictures by
`electricity" sent 15 photographs by telephone from Cleveland to New York City, such photos suitable for
`newspaper reproduction. Previously, photographs had been sent over the radio using this process.[10]
`
`Wireless transmission
`
`As a designer for the Radio Corporation of America (RCA), 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. Radio fax is still in common use today for transmitting weather charts and
`information to ships at sea. Also in 1924, Herbert E. Ives of AT&T Corporation transmitted and
`reconstructed the first color facsimile, using color separations. Around 1952 or so, Finch Facsimile, a
`highly developed machine, was described in detail in a book; it was never manufactured in quantity.
`
`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.
`
`Telephone transmission
`
`In 1964, Xerox Corporation introduced (and patented) what many consider to be the first commercialized
`version of the modern fax machine, under the name (LDX) or Long Distance Xerography. This model
`was superseded two years later with a unit that would truly set the standard for fax machines for years to
`come. Up until this point facsimile machines were very expensive and hard to operate. In 1966, Xerox
`released the Magnafax Telecopier, a smaller, 46-pound facsimile machine. 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.[11][12]
`
`By the late 1970s, many companies around the world (especially Japan), entered the fax market. Very
`shortly after a new wave of more compact, faster and efficient fax machines would hit the market. Xerox
`continued to refine the fax machine for years after their ground-breaking first machine. In later years it
`would be combined with copier equipment to create the hybrid machines we have today that copy, scan
`and fax. Some of the lesser known capabilities of the Xerox fax technologies included their Ethernet
`enabled Fax Services on their 8000 workstations in the early 1980s.
`
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`

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`Prior to the introduction of the ubiquitous fax machine, one of the first being the Exxon Qwip[13] in the
`mid-1970s, facsimile machines worked by optical scanning of a document or drawing spinning on a
`drum. The reflected light, varying in intensity according to the light and dark areas of the document, was
`focused on a photocell so that the current in a circuit varied with the amount of light. This current was
`used to control a tone generator (a modulator), the current determining the frequency of the tone
`produced. This audio tone was then transmitted using an acoustic coupler (a speaker, in this case)
`attached to the microphone of a common telephone handset. At the receiving end, a handset’s speaker
`was attached to an acoustic coupler (a microphone), and a demodulator converted the varying tone into a
`variable current that controlled the mechanical movement of a pen or pencil to reproduce the image on a
`blank sheet of paper on an identical drum rotating at the same rate.
`
`Computer facsimile interface
`
`In 1985, Dr. Hank Magnuski, founder of GammaLink, produced the first computer fax board, called
`GammaFax.
`Capabilities
`
`There are several indicators of fax capabilities: Group, class, data transmission rate, and conformance
`with ITU-T (formerly CCITT) recommendations.
`
`Fax machines utilize standard PSTN lines and telephone numbers.
`
`Group
`
`Analog
`
`Group 1 and 2 faxes are sent in the same manner as a frame of analog television, with each scanned line
`transmitted as a continuous analog signal. Horizontal resolution depended upon the quality of the
`scanner, transmission line, and the printer. Analog fax machines are obsolete and no longer
`manufactured. ITU-T Recommendations T.2 and T.3 were withdrawn as obsolete in July 1996.
`
`◾ Group 1 faxes conform to the ITU-T Recommendation T.2. Group 1 faxes take six minutes to
`transmit a single page, with a vertical resolution of 96 scan lines per inch. Group 1 fax machines
`are obsolete and no longer manufactured.
`◾ Group 2 faxes conform to the ITU-T Recommendations T.30 and T.3. Group 2 faxes take three
`minutes to transmit a single page, with a vertical resolution of 96 scan lines per inch. Group 2 fax
`machines are almost obsolete, and are no longer manufactured. Group 2 fax machines can
`interoperate with Group 3 fax machines.
`
`Digital
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`A major breakthrough in the development of the
`modern facsimile system was the result of digital
`technology, where the analog signal from scanners
`was digitized and then compressed, resulting in the
`ability to transmit high rates of data across standard
`phone lines. The first digital fax machine was the
`Dacom Rapidfax first sold in late 1960s, which
`incorporated digital data compression technology
`developed by Lockheed for transmission of images
`from satellites.[11][12]
`
`Group 3 and 4 faxes are digital formats, and take
`advantage of digital compression methods to greatly
`reduce transmission times.
`
`The Dacom DFC-10—the first digital fax machine.
`[11]
`
`The chip in a fax machine. Only about one quarter
`of the length is shown. The thin line in the middle
`consists of photosensitive pixels. The read-out
`circuit is at left.
`
`◾ Group 3 faxes conform to the ITU-T
`Recommendations T.30 and T.4. Group 3 faxes
`take between six and fifteen seconds to
`transmit a single page (not including the initial
`time for the fax machines to handshake and
`synchronize). The horizontal and vertical
`resolutions are allowed by the T.4 standard to
`vary among a set of fixed resolutions:
`◾ Horizontal: 100 scan lines per inch
`◾ Vertical: 100 scan lines per inch
`("Basic")
`◾ Horizontal: 200 or 204 scan lines per
`inch
`◾ Vertical: 100 or 98 scan lines per
`inch ("Standard")
`◾ Vertical: 200 or 196 scan lines per
`inch ("Fine")
`◾ Vertical: 400 or 391 (note not 392)
`scan lines per inch ("Superfine")
`◾ Horizontal: 300 scan lines per inch
`◾ Vertical: 300 scan lines per inch
`◾ Horizontal: 400 or 408 scan lines per
`inch
`◾ Vertical: 400 or 391 scan lines per
`inch ("Ultrafine")
`◾ Group 4 faxes conform to the ITU-T
`Recommendations T.563, T.503, T.521, T.6,
`T.62, T.70, T.411 to T.417. They are designed
`to operate over 64 kbit/s digital ISDN circuits.
`The allowed resolutions, a superset of those in the T.4 recommendation, are specified in the T.6
`recommendation.[14]
`
`CCD MN8051 Matsushita CCD side, monochrome
`2048-bit linear sensor +cm (centimeters)
`
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`

`Fax Over IP (FoIP) can transmit and receive pre-digitized documents at near realtime speeds using ITU-T
`recommendation T.38 to send digitised images over an IP network using JPEG compression. T.38 is
`designed to work with VoIP services and often supported by analog telephone adapters used by legacy
`fax machines that need to connect through a VoIP service. Scanned documents are limited to the amount
`of time the user takes to load the document in a scanner and for the device to process a digital file. The
`resolution can vary from as little as 150 DPI to 9600 DPI or more. This type of faxing is not related to the
`e-mail to fax service that still uses fax modems at least one way.
`
`Class
`
`Computer modems are often designated by a particular fax class, which indicates how much processing is
`offloaded from the computer's CPU to the fax modem.
`
`◾ Class 1 fax devices do fax data transfer where the T.4/T.6 data compression and T.30 session
`management are performed by software on a controlling computer. This is described in ITU-T
`recommendation T.31.[15]
`◾ Class 2 fax devices perform T.30 session management themselves, but the T.4/T.6 data
`compression is performed by software on a controlling computer. The relevant ITU-T
`recommendation is T.32.[15]
`◾ Class 2.0 is different from Class 2.
`◾ Class 2.1 is an improvement of Class 2.0. Class 2.1 fax devices are referred to as "super G3"; they
`seem to be a little faster than Class 1/2/2.0.
`◾ Class 3 fax devices are responsible for virtually the entire fax session, given little more than a
`phone number and the text to send (including rendering ASCII text as a raster image). These
`devices are not common.
`
`Data transmission rate
`
`Several different telephone line modulation techniques are used by fax machines. They are negotiated
`during the fax-modem handshake, and the fax devices will use the highest data rate that both fax devices
`support, usually a minimum of 14.4 kbit/s for Group 3 fax.
`
`ITU Standard Released Date
`V.27
`1988
`V.29
`1988
`V.17
`1991
`V.34
`1994
`V.34bis
`1998
`ISDN
`
`Modulation Method
`Data Rates (bit/s)
`PSK
`4800, 2400
`QAM
`9600, 7200, 4800
`14,400; 12,000; 9600; 7200 TCM
`28,800
`QAM
`33,600
`QAM
`64,000
`digital
`
`Note that "Super Group 3" faxes use V.34bis modulation that allows a data rate of up to 33.6 kbit/s.
`
`Compression
`
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`As well as specifying the resolution (and allowable physical size of the image being faxed), the ITU-T
`T.4 recommendation specifies two compression methods for decreasing the amount of data that needs to
`be transmitted between the fax machines to transfer the image. The two methods defined in T.4 are:[16]
`
`◾ Modified Huffman (MH), and
`◾ Modified READ (MR) (Relative Element Address Designate[17]), optional
`
`An additional method is specified in T.6:[14]
`
`◾ Modified Modified READ (MMR)
`
`Later, other compression techniques were added as options to ITU-T recommendation T.30, such as the
`more efficient JBIG (T.82, T.85) for bi-level content, and JPEG (T.81), T.43, MRC (T.44), and T.45 for
`grayscale, palette, and colour content.[18] Fax machines can negotiate at the start of the T.30 session to use
`the best technique implemented on both sides.
`
`Modified Huffman
`
`Modified Huffman (MH), specified in T.4 as the one-dimensional coding scheme, is a codebook-based
`run-length encoding scheme optimised to efficiently compress whitespace.[16] As most faxes consist
`mostly of white space, this minimises the transmission time of most faxes. Each line scanned is
`compressed independently of its predecessor and successor.[16]
`
`Modified READ
`
`Modified READ (MR), specified as an optional two-dimensional coding scheme in T.4, encodes the first
`scanned line using MH.[16] The next line is compared to the first, the differences determined, and then the
`differences are encoded and transmitted.[16] This is effective as most lines differ little from their
`predecessor. This is not continued to the end of the fax transmission, but only for a limited number of
`lines until the process is reset and a new 'first line' encoded with MH is produced. This limited number of
`lines is to prevent errors propagating throughout the whole fax, as the standard does not provide for error-
`correction. MR is an optional facility, and some fax machines do not use MR in order to minimise the
`amount of computation required by the machine. The limited number of lines is two for 'Standard'
`resolution faxes, and four for 'Fine' resolution faxes.
`
`Modified Modified READ
`
`The ITU-T T.6 recommendation adds a further compression type of Modified Modified READ (MMR),
`which simply allows for a greater number of lines to be coded by MR than in T.4.[14] This is because T.6
`makes the assumption that the transmission is over a circuit with a low number of line errors such as
`digital ISDN. In this case, there is no maximum number of lines for which the differences are encoded.
`
`JBIG
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`In 1999, ITU-T recommendation T.30 added JBIG (ITU-T T.82) as another lossless bi-level compression
`algorithm, or more precisely a "fax profile" subset of JBIG (ITU-T T.85). JBIG-compressed pages result
`in 20% to 50% faster transmission than MMR-compressed pages, and up to 30-times faster transmission
`if the page includes halftone images.
`
`JBIG performs adaptive compression, that is both the encoder and decoder collect statistical information
`about the transmitted image from the pixels transmitted so far, in order to predict the probability for each
`next pixel being either black or white. For each new pixel, JBIG looks at ten nearby, previously
`transmitted pixels. It counts, how often in the past the next pixel has been black or white in the same
`neighborhood, and estimates from that the probability distribution of the next pixel. This is fed into an
`arithmetic coder, which adds only a small fraction of a bit to the output sequence if the more probable
`pixel is then encountered.
`
`The ITU-T T.85 "fax profile" constrains some optional features of the full JBIG standard, such that
`codecs do not have to keep data about more than the last three pixel rows of an image in memory at any
`time. This allows the streaming of "endless" images, where the height of the image may not be known
`until the last row is transmitted.
`
`ITU-T T.30 allows fax machines to negotiate one of two options of the T.85 "fax profile":
`
`◾ In "basic mode", the JBIG encoder must split the image into horizontal stripes of 128 lines
`(parameter L0=128), and restart the arithmetic encoder for each stripe.
`◾ In "option mode", there is no such constraint.
`
`Matsushita Whiteline Skip
`
`A proprietary compression scheme employed on Panasonic fax machines is Matsushita Whiteline Skip
`(MWS). It can be overlaid on the other compression schemes, but is operative only when two Panasonic
`machines are communicating with one another. This system detects the blank scanned areas between
`lines of text, and then compresses several blank scan lines into the data space of a single character. (JBIG
`implements a similar technique called "typical prediction", if header flag TPBON is set to 1.)
`
`Typical characteristics
`
`Group 3 fax machines transfer one or a few printed or handwritten pages per minute in black-and-white
`(bitonal) at a resolution of 204×98 (normal) or 204×196 (fine) dots per square inch. The transfer rate is
`14.4 kbit/s or higher for modems and some fax machines, but fax machines support speeds beginning
`with 2400 bit/s and typically operate at 9600 bit/s. The transferred image formats are called ITU-T
`(formerly CCITT) fax group 3 or 4.
`
`The most basic fax mode transfers black and white colors only. The original page is scanned in a
`resolution of 1728 pixels/line and 1145 lines/page (for A4). The resulting raw data is compressed using a
`modified Huffman code optimized for written text, achieving average compression factors of around 20.
`Typically a page needs 10 s for transmission, instead of about 3 minutes for the same uncompressed raw
`data of 1728×1145 bits at a speed of 9600 bit/s. The compression method uses a Huffman codebook for
`run lengths of black and white runs in a single scanned line, and it can also use the fact that two adjacent
`scanlines are usually quite similar, saving bandwidth by encoding only the differences.
`
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`Fax classes denote the way fax programs interact with fax hardware. Available classes include Class 1,
`Class 2, Class 2.0 and 2.1, and Intel CAS. Many modems support at least class 1 and often either Class 2
`or Class 2.0. Which is preferable to use depends on factors such as hardware, software, modem firmware,
`and expected use.
`
`Printing process
`
`Fax machines from the 1970s to the 1990s often used direct thermal printers with rolls of thermal paper
`as their printing technology, but since the mid-1990s there has been a transition towards plain-paper
`faxes:- thermal transfer printers, inkjet printers and laser printers.
`
`One of the advantages of inkjet printing is that inkjets can affordably print in color; therefore, many of
`the inkjet-based fax machines claim to have color fax capability. There is a standard called ITU-T30e
`(formally ITU-T Recommendation T.30 Annex E [19]) for faxing in color; unfortunately, it is not widely
`supported, so many of the color fax machines can only fax in color to machines from the same
`manufacturer.
`
`Stroke speed
`
`Stroke speed in facsimile systems is the rate at which a fixed line perpendicular to the direction of
`scanning is crossed in one direction by a scanning or recording spot. Stroke speed is usually expressed as
`a number of strokes per minute. When the fax system scans in both directions, the stroke speed is twice
`this number. In most conventional 20th century mechanical systems, the stroke speed is equivalent to
`drum speed.[20]
`
`Fax paper
`
`As a precaution, thermal fax paper is typically not accepted in
`archives or as documentary evidence in some courts of law unless
`photocopied. This is because the image-forming coating is
`eradicable and brittle, and it tends to detach from the medium
`after a long time in storage.[21]
`Internet fax
`
`One popular alternative is to subscribe to an Internet fax service,
`allowing users to send and receive faxes from their personal
`computers using an existing email account. No software, fax
`server or fax machine is needed. Faxes are received as attached
`TIFF or PDF files, or in proprietary formats that require the use of the service provider's software. Faxes
`can be sent or retrieved from anywhere at any time that a user can get Internet access. Some services offer
`secure faxing to comply with stringent HIPAA and Gramm–Leach–Bliley Act requirements to keep
`medical information and financial information private and secure. Utilizing a fax service provider does
`not require paper, a dedicated fax line, or consumable resources.[22]
`
`Paper roll for direct thermal fax
`machine
`
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`

`Another alternative to a physical fax machine is to make use of computer software which allows people
`to send and receive faxes using their own computers, utilizing fax servers and unified messaging. A
`virtual (email) fax can be printed out and then signed and scanned back to computer before being
`emailed. Also the sender can attach a digital signature to the document file.
`See also
`
`◾ Black fax
`◾ Called subscriber identification (CSID)
`◾ Error correction mode (ECM)
`◾ Fax art
`◾ Fax demodulator
`◾ Fax modem
`◾ Fax server
`◾ Faxlore
`◾ Fultograph
`◾ Internet fax
`
`References
`
`◾ Junk fax
`◾ Radiofax—image transmission over HF
`radio
`◾ Slow-scan television
`◾ T.38 Fax-over-IP
`◾ Telautograph
`◾ Telex
`◾ Transmitting Subscriber Identification
`(TSID)
`
`1. Rouse, Margaret (June 2006). "What is
`fax?" (http://searchnetworking.techtarget.com/defini
`SearchNetworking. Retrieved 25 July 2012.
`2. Adams, Ken (7 November 2007). "Enforceability
`of Fax and Scanned Signature
`Pages" (http://www.adamsdrafting.com/2007/11/07/
`and-scanned-signatures/). AdamsDrafting.
`Retrieved 25 July 2012.
`3. http://www.lawson.co.jp/service/counter/fax.html
`4. Fackler, Martin (13 February 2013). "In High-
`Tech Japan, the Fax Machines Roll
`On" (http://www.nytimes.com/2013/02/14/world/asi
`japan-the-fax-machine-is-anything-but-a-
`relic.html?pagewanted=1&_r=0&ref=world). The
`New York Times. Retrieved 14 February 2013.
`5. Oi, Mariko (2012-07-31). "BBC News - Japan and
`the fax: A love
`affair" (http://www.bbc.co.uk/news/magazine-
`19045837). Bbc.co.uk. Retrieved 2014-02-16.
`6. “Mr. Bain’s Electric Printing Telegraph,”
`Mechanics' Magazine April 13, 1844, 268-70
`7. "Istituto Tecnico Industriale, Rome, Italy. Italian
`biography of Giovanni
`Caselli" (http://www.itisgalileiroma.it/shed/shed0/sh
`Itisgalileiroma.it. Retrieved 2014-02-16.
`8. The Hebrew University of Jerusalem - Giovanni
`Caselli biography
`(http://chem.ch.huji.ac.il/history/caselli.html)
`
`9. "The History of Fax – from 1843 to Present
`Day" (http://faxauthority.com/fax-history/). Fax
`Authority. Retrieved 25 July 2012.
`10. The Montreal Gazette, May 20, 1924, page 10,
`column 3
`11. The implementation of a personal computer-based
`digital facsimile information distribution system
`by Chung, Edward C.
`(http://etd.ohiolink.edu/view.cgi/Chung%
`20Edward%20C.pdf?ohiou1183661772)
`12. Fax: The Principles and Practice of Facsimile
`Communication, Daniel M. Costigan, Chilton
`Book Company, 1971, pages 112–114, 213, 239
`13. New York Times. An Exxon Sale To Harris Unit
`(http://www.nytimes.com/1985/02/22/business/an-
`exxon-sale-to-harris-unit-the-exxon-corporation-
`said.html), New York Times, February 22, 1985.
`14. "T.6: Facsimile coding schemes and coding
`control functions for Group 4 facsimile
`apparatus" (http://www.itu.int/rec/T-REC-T.6/en).
`ITU-T. November 1988. Retrieved 2013-12-28.
`15. Peterson, Kerstin Day (2000). Business telecom
`systems: a guide to choosing the best technologies
`and services (http://books.google.com/books?
`id=W79R0niNU5wC&pg=PA191). Focal Press.
`pp. 191–192. ISBN 1578200415. Retrieved
`2011-04-02.
`
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`

`

`16. "T.4: Standardization of Group 3 facsimile
`terminals for document
`transmission" (http://www.itu.int/rec/T-REC-
`T.4/en). ITU-T. 2003-07. Retrieved 2013-12-28.
`Check date values in: |date= (help)
`17. International digital facsimile coding standards
`(http://ieeexplore.ieee.org/xpl/login.jsp?
`tp=&arnumber=1456020&url=http%3A%2F%
`2Fieeexplore.ieee.org%2Fiel5%2F5%2F31291%
`2F01456020.pdf%3Farnumber%3D1456020),
`Hunter, R., and Robinson, A.H., Proceedings of
`the IEEE Volume 68 Issue 7, pp 854–867, July
`1980
`18. "T.30: Procedures for document facsimile
`transmission in the general switched telephone
`network" (http://www.itu.int/rec/T-REC-T.30).
`ITU-T. 2005-09. Retrieved 2013-12-28. Check
`date values in: |date= (help)
`
`20.
`
`19. tsbmail. "T.30 : Procedures for document
`facsimile transmission in the general switched
`telephone network" (http://www.itu.int/rec/T-
`REC-T.30-200509-I/en). Itu.int. Retrieved
`2014-02-16.
` This article incorporates public domain
`material from the General Services
`Administration document "Federal Standard
`1037C" (http://www.its.bldrdoc.gov/fs-1037/fs-
`1037c.htm) (in support of MIL-STD-188).
`21. "4.12 Filing rules: 19.Newspaper extracts or
`thermal facsimile paper should not be preserved
`as archives. Such extracts should be photocopied
`and the copy preserved. The original can then be
`destroyed." Office of Corporate & Legal Affairs,
`University College Cork, Ireland
`22. "Online Fax vs Traditional
`Fax" (http://blog.efax.com/blog/online-fax-2/five-
`reasons-to-adopt-online-fax). eFax. 16 May 2013.
`Retrieved 8 December 2013.
`
`Further reading
`
`◾ Coopersmith, Jonathan, Faxed: The Rise and Fall of the Fax Machine (Johns Hopkins University
`Press, 2015) 308 pp.
`External links
`
`◾ Group 3 Facsimile Communication
`
`Look up fax or facsimile
`in Wiktionary, the free
`dictionary.
`
`Wikimedia Commons has
`media related to Fax
`machines.
`(http://www.garretwilson.com/essays/computers/group3fax.html) a '97 essay with technical details
`on compression and error codes, and call establishment and release.
`◾ ITU T.30 Recommendation (http://www.itu.int/rec/T-REC-T.30/en)
`
`Retrieved from "http://en.wikipedia.org/w/index.php?title=Fax&oldid=662690631"
`
`Categories: Fax 1843 introductions American inventions Computer peripherals English inventions
`German inventions
`Italian inventions
`ITU-T recommendations
`Japanese inventions
`Office equipment Scottish inventions Telecommunications equipment
`
`http://en.wikipedia.org/wiki/Fax
`
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