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Dial-up Internet access is a form of
Internet access Internet access is the ability of individuals and organizations to connect to the Internet using computer terminals, computers, and other devices; and to access services such as email and the World Wide Web. Internet access is sold by Interne ...
that uses the facilities of the
public switched telephone network The public switched telephone network (PSTN) provides infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telep ...
(PSTN) to establish a connection to an
Internet service provider An Internet service provider (ISP) is an organization that provides services for accessing, using, or participating in the Internet. ISPs can be organized in various forms, such as commercial, community-owned, non-profit, or otherwise priva ...
(ISP) by dialing a
telephone number A telephone number is a sequence of digits assigned to a landline telephone subscriber station connected to a telephone line or to a wireless electronic telephony device, such as a radio telephone or a mobile telephone, or to other devices f ...
on a conventional
telephone line A telephone line or telephone circuit (or just line or circuit industrywide) is a single-user circuit on a telephone communication system. It is designed to reproduce speech of a quality that is understandable. It is the physical wire or ot ...
. Dial-up connections use
modem A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by modulating one or more c ...
s to decode audio signals into data to send to a router or computer, and to encode signals from the latter two devices to send to another modem.


History

In 1979, Tom Truscott and Jim Ellis, graduates of
Duke University Duke University is a private research university in Durham, North Carolina. Founded by Methodists and Quakers in the present-day city of Trinity in 1838, the school moved to Durham in 1892. In 1924, tobacco and electric power industrialist Jam ...
, created an early predecessor to dial-up Internet access called the
USENET Usenet () is a worldwide distributed discussion system available on computers. It was developed from the general-purpose Unix-to-Unix Copy (UUCP) dial-up network architecture. Tom Truscott and Jim Ellis conceived the idea in 1979, and it wa ...
. The USENET was a
UNIX Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, ...
based system that used a dial-up connection to transfer data through telephone modems. Dial-up Internet has been around since the 1980s via public providers such as NSFNET-linked universities. The BBC established Internet access via
Brunel University Brunel University London is a public research university located in the Uxbridge area of London, England. It was founded in 1966 and named after the Victorian engineer and pioneer of the Industrial Revolution, Isambard Kingdom Brunel. In Jun ...
in the United Kingdom in 1989. Dial-up was first offered commercially in 1992 by Pipex in the United Kingdom and Sprint in the United States. After the introduction of commercial
broadband In telecommunications, broadband is wide bandwidth data transmission which transports multiple signals at a wide range of frequencies and Internet traffic types, that enables messages to be sent simultaneously, used in fast internet connections. ...
in the late 1990s, dial-up Internet access became less popular in the mid-2000s. It is still used where other forms are not available or where the cost is too high, as in some rural or remote areas.


Modems

Because there was no technology to allow different carrier signals on a telephone line at the time, dial-up internet access relied on using audio communication. In exactly the same way that one might pick up the phone and talk to someone, a modem would take the digital data from a computer, modulate it into an audio signal and send it to a receiving modem. This receiving modem would demodulate the signal from analogue noise, back into digital data for the computer to process. The simplicity of this arrangement meant that people would be unable to use their phone line for verbal communication until the call was finished. The Internet speed using this technology can drop to 21.6 kbit/s or less. Poor condition of the telephone line, high noise level and other factors all affect dial-up speed. For this reason, it is popularly called the 21600 Syndrome.


Availability

Dial-up connections to the Internet require no additional infrastructure other than the
telephone network A telephone network is a telecommunications network that connects telephones, which allows telephone calls between two or more parties, as well as newer features such as fax and internet. The idea was revolutionized in the 1920s, as more and mor ...
and the modems and servers needed to make and answer the calls. Because telephone access is widely available, dial-up is often the only choice available for rural or remote areas, where
broadband In telecommunications, broadband is wide bandwidth data transmission which transports multiple signals at a wide range of frequencies and Internet traffic types, that enables messages to be sent simultaneously, used in fast internet connections. ...
installations are not prevalent due to low population density and high infrastructure cost. Dial-up access may also be an alternative for users on limited budgets, as it is offered free by some ISPs, though broadband is increasingly available at lower prices in many countries due to market competition. Dial-up requires time to establish a telephone connection (up to several seconds, depending on the location) and perform configuration for protocol synchronization before data transfers can take place. In locales with telephone connection charges, each connection incurs an incremental cost. If calls are time-metered, the duration of the connection incurs costs. Dial-up access is a transient connection, because either the user, ISP or phone company terminates the connection. Internet service providers will often set a limit on connection durations to allow sharing of resources, and will disconnect the user—requiring reconnection and the costs and delays associated with it. Technically inclined users often find a way to disable the auto-disconnect program such that they can remain connected for more days than one. A 2008 Pew Research Center study stated that only 10% of US adults still used dial-up Internet access. The study found that the most common reason for retaining dial-up access was high broadband prices. Users cited lack of infrastructure as a reason less often than stating that they would never upgrade to broadband. That number had fallen to 6% by 2010, and to 3% by 2013. A survey conducted in 2018 estimated that 0.3% of Americans were using dial-up by 2017. The CRTC estimated that there were 336,000 Canadian dial-up users in 2010.


Replacement by broadband

Broadband Internet access via cable,
digital subscriber line Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric dig ...
,
wireless broadband Wireless broadband is telecommunications technology that provides high-speed wireless Internet access or computer networking access over a wide area. The term comprises both fixed and mobile broadband. The term broadband Originally the wor ...
,
mobile broadband Mobile broadband is the marketing term for wireless Internet access via mobile networks. Access to the network can be made through a portable modem, wireless modem, or a tablet/ smartphone (possibly tethered) or other mobile device. The fir ...
,
satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...
and
FTTx Fiber to the ''x'' (FTTX; also spelled "fibre") or fiber in the loop is a generic term for any broadband network architecture using optical fiber to provide all or part of the local loop used for last mile telecommunications. As fiber optic ...
has replaced dial-up access in many parts of the world. Broadband connections typically offer speeds of 700 kbit/s or higher for two-thirds more than the price of dial-up on average. In addition, broadband connections are always on, thus avoiding the need to connect and disconnect at the start and end of each session. Broadband does not require the exclusive use of a phone line, and thus one can access the Internet and at the same time make and receive voice phone calls without having a second phone line. However, many rural areas remain without high speed Internet despite the eagerness of potential customers. This can be attributed to population, location, or sometimes ISPs' lack of interest due to little chance of profitability and high costs to build the required infrastructure. Some dial-up ISPs have responded to the increased competition by lowering their rates and making dial-up an attractive option for those who merely want email access or basic Web browsing. Dial-up has seen a significant fall in usage, with the potential to cease to exist in future as more users switch to broadband. In 2000, about 34% of the U.S. population used dial-up, compared to 3% in 2013. One contributing factor is the bandwidth requirements of newer computer programs, like operating systems and
antivirus Antivirus software (abbreviated to AV software), also known as anti-malware, is a computer program used to prevent, detect, and remove malware. Antivirus software was originally developed to detect and remove computer viruses, hence the nam ...
software, which automatically download sizeable updates in the background when a connection to the Internet is first made. These background downloads can take several minutes or longer and, until all updates are completed, they can severely impact the amount of bandwidth available to other applications like Web browsers. Since an "always on" broadband is the norm expected by most newer applications being developed, this automatic background downloading trend is expected to continue to eat away at dial-up's available bandwidth to the detriment of dial-up users' applications. Many newer websites also now assume broadband speeds as the norm, and when connected to with slower dial-up speeds may drop (timeout) these slower connections to free up communication resources. On websites that are designed to be more dial-up friendly, use of a reverse proxy prevents dial-ups from being dropped as often but can introduce long wait periods for dial-up users caused by the buffering used by a reverse proxy to bridge the different data rates. Despite the rapid decline, dial-up Internet still exists in some rural areas, and many areas of developing and underdeveloped nations, although wireless and satellite broadband are providing faster connections in many rural areas where fibre or copper may be uneconomical. In 2010, it was estimated that there were 800,000 dial-up users in the UK. BT turned off its dial-up service in 2013.


Performance

Modern dial-up modems typically have a maximum theoretical transfer speed of 56 kbit/s (using the V.90 or
V.92 V.92 is an ITU-T recommendation, titled ''Enhancements to Recommendation V.90'', that establishes a modem standard allowing near 56 kb/s download and 48 kb/s upload rates. With V.92 PCM is used for both the upstream and downstream connections; pre ...
protocol Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technology ...
), although in most cases, 40–50 kbit/s is the norm. Factors such as phone line noise as well as the quality of the modem itself play a large part in determining connection speeds. Some connections may be as low as 20 kbit/s in extremely noisy environments, such as in a hotel room where the phone line is shared with many extensions, or in a rural area, many miles from the phone exchange. Other factors such as long loops,
loading coil A loading coil or load coil is an inductor that is inserted into an electronic circuit to increase its inductance. The term originated in the 19th century for inductors used to prevent signal distortion in long-distance telegraph transmission c ...
s, pair gain, electric fences (usually in rural locations), and digital loop carriers can also slow connections to 20 kbit/s or lower. Analog telephone lines are digitally switched and transported inside a
Digital Signal 0 Digital Signal 0 (DS0) is a basic digital signaling rate of 64 kilobits per second ( kbit/s), corresponding to the capacity of one analog voice-frequency-equivalent communication channel. The DS0 rate, and its equivalents E0 in the E-carrier system ...
once reaching the telephone company's equipment.
Digital Signal 0 Digital Signal 0 (DS0) is a basic digital signaling rate of 64 kilobits per second ( kbit/s), corresponding to the capacity of one analog voice-frequency-equivalent communication channel. The DS0 rate, and its equivalents E0 in the E-carrier system ...
is 64 kbit/s and reserves 8 kbit/s for signaling information; therefore a 56 kbit/s connection is the highest that will ever be possible with analog phone lines. Dial-up connections usually have latency as high as 150 ms or even more, higher than many forms of broadband, such as cable or DSL, but typically less than satellite connections. Longer latency can make video conferencing and online gaming difficult, if not impossible. An increasing amount of Internet content such as
streaming media Streaming media is multimedia that is delivered and consumed in a continuous manner from a source, with little or no intermediate storage in network elements. ''Streaming'' refers to the delivery method of content, rather than the content i ...
will not work at dial-up speeds. Video games released from the mid-1990s to the mid-2000s that utilized Internet access such as '' EverQuest'', '' Red Faction'', ''
Warcraft 3 ''Warcraft III: Reign of Chaos'' is a high fantasy real-time strategy computer video game developed and published by Blizzard Entertainment released in July 2002. It is the second sequel to '' Warcraft: Orcs & Humans'', after '' Warcraft II: Tid ...
'', ''
Final Fantasy XI also known as ''Final Fantasy XI Online'', is a massively multiplayer online role-playing game (MMORPG), originally developed and published by Squaresoft and then published by Square Enix as the eleventh main installment of the ''Final Fantas ...
'', ''
Phantasy Star Online ''Phantasy Star Online'' is an online role-playing game (RPG) developed by Sonic Team and published by Sega in 2000 for the Dreamcast. It was the first online RPG for game consoles; players adventure with up to three others over the internet ...
'', '' Guild Wars'', '' Unreal Tournament'', '' Halo: Combat Evolved'', '' Audition'', '' Quake 3: Arena'', '' Starsiege: Tribes'' and '' Ragnarok Online'', etc., accommodated for 56k dial-up with limited data transfer between the game servers and user's personal computer. The first consoles to provide Internet connectivity, the Dreamcast and PlayStation 2, supported dial-up as well as broadband. The
GameCube The is a home video game console developed and released by Nintendo in Japan on September 14, 2001, in North America on November 18, 2001, and in PAL territories in 2002. It is the successor to the Nintendo 64 (1996), and predecessor of the ...
could use dial-up and broadband connections, but this was used in very few games and required a separate adapter. The original Xbox exclusively required a broadband connection. Many computer and video games released since the mid-2000s do not even include the option to use dial-up. However, there are exceptions to this, such as '' Vendetta Online'', which can still run on a dial-up modem.


Using compression to exceed 56k

The V.42, V.42bis and V.44 standards allow modems to accept compressed data at a rate faster than the line rate. These algorithms use data compression to achieve higher throughput. For instance, a 53.3 kbit/s connection with V.44 can transmit up to 53.3 × 6 = 320 kbit/s if the offered data stream can be compressed that much. However, the compression ratio varies considerably. ZIP archives,
JPEG JPEG ( ) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and imag ...
images, MP3, video, etc. are already compressed. A modem might be sending compressed files at approximately 50 kbit/s, uncompressed files at 160 kbit/s, and pure text at 320 kbit/s, or any rate in this range.


Compression by the ISP

As telephone-based Internet lost popularity in the mid-2000s, some Internet service providers such as TurboUSA, Netscape, CdotFree, and NetZero started using data compression to increase the perceived speed. As an example, EarthLink advertises "surf the Web up to 7x faster" using a compression program on images, text/html, and SWF flash animations prior to transmission across the phone line. The pre-compression operates much more efficiently than the on-the-fly compression of V.44 modems. Typically, website text is compacted to 5%, thus increasing effective throughput to approximately 1000 kbit/s, and JPEG/GIF/PNG images are lossy-compressed to 15–20%, increasing effective throughput up to 300 kbit/s. The drawback of this approach is a loss in quality, where the graphics acquire
compression artifacts A compression artifact (or artefact) is a noticeable distortion of media (including images, audio, and video) caused by the application of lossy compression. Lossy data compression involves discarding some of the media's data so that it beco ...
taking on a blurry or colorless appearance. However, the transfer speed is dramatically improved. If desired, the user may choose to view uncompressed images instead, but at a much slower load rate. Since streaming music and video are already compressed at the source, they are typically passed by the ISP unaltered.


Usage in other devices

Other devices, such as satellite receivers and
digital video recorder A digital video recorder (DVR) is an electronic device that records video in a digital format to a disk drive, USB flash drive, SD memory card, SSD or other local or networked mass storage device. The term includes set-top boxes with direct to ...
s (such as TiVo), have also used dial-up connection using a household phone socket. This connection allowed to download data at request and to report usage (e.g. ordering
pay-per-view Pay-per-view (PPV) is a type of pay television or webcast service that enables a viewer to pay to watch individual events via private telecast. Events can be purchased through a multichannel television platform using their electronic program g ...
) to the service provider. This feature did not require an
Internet service provider An Internet service provider (ISP) is an organization that provides services for accessing, using, or participating in the Internet. ISPs can be organized in various forms, such as commercial, community-owned, non-profit, or otherwise priva ...
account – instead, the device's internal modem dialed the server of the service provider directly. These devices may experience difficulties when operating on a
VoIP Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet t ...
line because the compression could alter the modem signal. Later, these devices moved to using an
Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1 ...
connection to the user's Internet router, which became a more convenient approach due to the growth in popularity of broadband. Note that the values given are maximum values, and actual values may be slower under certain conditions (for example, noisy phone lines).


See also

*
Registered jack A registered jack (RJ) 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. Registration interfaces were first defined in th ...


References

{{DEFAULTSORT:Dial-Up Internet Access American inventions Internet access Web 1.0 Obsolete technologies