Typical noises of dial-up modem (North America and United Kingdom) while a modem is establishing connection with a local ISP-server in order to get access to the public Internet.
Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telephone line which could be connected using an RJ-11 connector.[1] Dial-up connections use modems 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 at the ISP.
Dial-up Internet reached its peak popularity during the dot-com bubble with the likes of ISPs such as Sprint, EarthLink, MSN Dial-up, NetZero, Prodigy, and America Online (more commonly known as AOL). This was in large part because broadband Internet did not become widely used until well into the 2000s. Since then, most dial-up access has been replaced by broadband.
History
56K dial-up modem used at a customer site
In 1979, Tom Truscott and Jim Ellis, graduates of Duke University, created an early predecessor to dial-up Internet access called the Usenet. The Usenet was a UNIX based system that used a dial-up connection to transfer data through telephone modems.[2]
Dial-up Internet access has existed since the 1980s via public providers such as NSFNET-linked universities in the United States. In the United Kingdom, JANET linked academic users, including a connection to the ARPANET via University College London, while Brunel University and the University of Kent offered dial-up UUCP to non-academic users in the late 1980s.[3][4][5]
Commercial dial-up Internet access was first offered in 1992 by Sprint in the United States and by Pipex in the United Kingdom.[6][7] After the introduction of commercial broadband in the late 1990s,[8] dial-up became less popular. In the United States, the availability of dial-up Internet access dropped from 40% of Americans in the early 2000s to 3% in the early 2010s.[9] It is still used where other forms are not available or where the cost is too high, as in some rural or remote areas.[10][11][12][13]
Banks of modems used by an ISP to provide dial-up Internet service
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. 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.[14]
The simplicity of this arrangement meant that people would be unable to use their phone line for verbal communication until the Internet 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.[15][16]
Availability
Dial-up connections to the Internet require no additional infrastructure other than the telephone network 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 installations are not prevalent due to low population density and high infrastructure cost.[11]
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.[17] That number had fallen to 6% by 2010,[18] and to 3% by 2013.[19]
A survey conducted in 2018 estimated that 0.3% of Americans were using dial-up by 2017.[20]
The CRTC estimated that there were 336,000 Canadian dial-up users in 2010.[21]
Replacement by broadband
Broadband Internet access via cable, digital subscriber line, wireless broadband, mobile broadband, satellite and FTTx 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.[18] 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.[22][23]
Dial-up has seen a significant fall in usage, with the potential to cease to exist in future as more users switch to broadband.[citation needed] In 2013, only about 3% of the U.S population used dial-up, compared to 30% in 2000.[24] One contributing factor is the bandwidth requirements of newer computer programs, like operating systems and antivirus 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,[citation needed] 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.[25] 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.[citation needed]
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.[26]
In 2012, it was estimated that 7% of Internet connections in New Zealand were dial-up. One NZ (formerly Vodafone) turned off its dial-up service in 2021.[27][28]
Performance
An example handshake of a dial-up modem
Modern dial-up modems typically have a maximum theoretical transfer speed of 56kbit/s (using the V.90 or V.92protocol), although in most cases, 40–50kbit/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.[citation needed]
Some connections may be as low as 20kbit/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 kilometres from the phone exchange. Other factors such as long loops, loading coils, pair gain, electric fences (usually in rural locations), and digital loop carriers can also slow connections to 20kbit/s or lower.
Note that the values given are maximum values, and actual values may be slower under certain conditions (for example, noisy phone lines).[29]
[The dial-up sounds are] a choreographed sequence that allowed these digital devices to piggyback on an analog telephone network. A phone line carries only the small range of frequencies in which most human conversation takes place: about three hundred to three thousand hertz. The modem works within these [telephone network] limits in creating sound waves to carry data across phone lines. What you're hearing is the way 20th century technology tunneled through a 19th century network; what you're hearing is how a network designed to send the noises made by your muscles as they pushed around air came to transmit anything [that can be] coded in zeroes and ones.
Analog telephone lines are digitally switched and transported inside a Digital Signal 0 once reaching the telephone company's equipment. Digital Signal 0 is 64kbit/s and reserves 8kbit/s for signaling information; therefore a 56kbit/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 will not work at dial-up speeds.
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 53.3kbit/s connection with V.44 can transmit up to 53.3 × 6 = 320kbit/s if the offered data stream can be compressed that much. However, the compression ratio varies considerably. ZIP archives, JPEG images, MP3, video, etc. are already compressed.[31] A modem might be sending compressed files at approximately 50kbit/s, uncompressed files at 160kbit/s, and pure text at 320kbit/s, or any rate in this range.[32]
As telephone-based Internet lost popularity by 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.[33]
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 1000kbit/s, and JPEG/GIF/PNG images are lossy-compressed to 15–20%, increasing effective throughput up to 300kbit/s.
The drawback of this approach is a loss in quality, where the graphics acquire compression artifacts 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
A TiVo Series2 video recorder's back panel. The telephone socket, located near the cooling fan exhaust, is a way for the machine to download its required electronic program guide data.
Other devices, such as satellite receivers and digital video recorders (such as TiVo), have also used a 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) to the service provider. This feature did not require an Internet service provider 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 line because the compression could alter the modem signal. Later, these devices moved to using an Ethernet connection to the user's Internet router, which became a more convenient approach due to the growth in popularity of broadband.
Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Work on the standard began in 1980 at Bell Labs and was formally standardized in 1988 in the CCITT "Red Book". By the time the standard was released, newer networking systems with much greater speeds were available, and ISDN saw relatively little uptake in the wider market. One estimate suggests ISDN use peaked at a worldwide total of 25 million subscribers at a time when 1.3 billion analog lines were in use. ISDN has largely been replaced with digital subscriber line (DSL) systems of much higher performance.
Digital subscriber line 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 digital subscriber line (ADSL), the most commonly installed DSL technology, for Internet access.
In telecommunications, broadband or high speed is the wide-bandwidth data transmission that exploits signals at a wide spread of frequencies or several different simultaneous frequencies, and is used in fast Internet access. The transmission medium can be coaxial cable, optical fiber, wireless Internet (radio), twisted pair cable, or satellite.
A digital subscriber line access multiplexer is a network device, often located in telephone exchanges, that connects multiple customer digital subscriber line (DSL) interfaces to a high-speed digital communications channel using multiplexing techniques. Its cable internet (DOCSIS) counterpart is the cable modem termination system.
Internet access is a facility or service that provides connectivity for a computer, a computer network, or other network device to the Internet, and for individuals or organizations to access or use applications such as email and the World Wide Web. Internet access is offered for sale by an international hierarchy of Internet service providers (ISPs) using various networking technologies. At the retail level, many organizations, including municipal entities, also provide cost-free access to the general public. Types of connections range from fixed-line cable to mobile and satellite.
A leased line is a private telecommunications circuit between two or more locations provided according to a commercial contract. It is sometimes also known as a private circuit, and as a data line in the UK. Typically, leased lines are used by businesses to connect geographically distant offices.
In telephony, pair gain is the transmission of multiple plain old telephone service (POTS) channels over the twisted pair local loop traditionally used for a single subscriber line in telephone systems. Pair gain has the effect of creating additional subscriber lines. This is typically used as an expedient way to solve subscriber line shortages at a location by using existing wiring, instead of installing new wires from the central office to the customer premises. The term was invented in the middle 20th century by analogy with earlier use of gain to extend telephone local loops far from the telephone exchange.
Satellite Internet access is Internet access provided through communication satellites; if it can sustain high speeds, it is termed satellite broadband. Modern consumer grade satellite Internet service is typically provided to individual users through geostationary satellites that can offer relatively high data speeds, with newer satellites using the Ku band to achieve downstream data speeds up to 506 Mbit/s. In addition, new satellite internet constellations are being developed in low-earth orbit to enable low-latency internet access from space.
In communications, Circuit Switched Data (CSD) is the original form of data transmission developed for the time-division multiple access (TDMA)-based mobile phone systems like Global System for Mobile Communications (GSM). After 2010 many telecommunication carriers dropped support for CSD, and CSD has been superseded by GPRS and EDGE (E-GPRS).
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; previously 56K modems only used PCM for downstream data. The recommendation was issued in November 2000, with amendments in July 2001 and March 2002.
Digital access carrier system (DACS) is the name used by British Telecom in the United Kingdom for a 0+2 pair gain system.
A web accelerator is a proxy server that reduces website access time. They can be a self-contained hardware appliance or installable software.
A digital subscriber line (DSL) modem is a device used to connect a computer or router to a telephone line which provides the digital subscriber line (DSL) service for connection to the Internet, which is often called DSL broadband. The modem connects to a single computer or router, through an Ethernet port, USB port, or is installed in a computer PCI slot.
In telecommunications, cable Internet access, shortened to cable Internet, is a form of broadband internet access which uses the same infrastructure as cable television. Like digital subscriber line and fiber to the premises services, cable Internet access provides network edge connectivity from the Internet service provider to an end user. It is integrated into the cable television infrastructure analogously to DSL which uses the existing telephone network. Cable TV networks and telecommunications networks are the two predominant forms of residential Internet access. Recently, both have seen increased competition from fiber deployments, wireless, mobile networks and satellite internet access.
Internet access is widely available in New Zealand, with 94% of New Zealanders having access to the internet as of January 2021. It first became accessible to university students in the country in 1989. As of June 2018, there are 1,867,000 broadband connections, of which 1,524,000 are residential and 361,000 are business or government.
Internet in India began in 1986 and was initially available only to the educational and research community. General public access to the internet in India began on 15 August 1995. By 2023, India had more than 900 million Internet users. It is reported that in 2022 an average mobile Internet consumption in India was 19.5 GB per month and the mobile data usage per month rose from 4.5 exabytes in 2018 to 14.4 exabytes in 2022.
BT Highway was a UK retail ISDN2e service from British Telecom which was announced in November 1997 and withdrawn in February 2007. In the domestic market, it was sold as BT Home Highway and for small businesses, BT Business Highway. These names were used simply to differentiate billing schemes; the hardware for both services used the name BT Highway. Unlike regular ISDN2e service where only a digital S interface is provided BT Highway provided both digital and analogue connections simplifying migration from regular POTS service.
A modulator-demodulator, commonly referred to as a 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 carrier wave signals to encode digital information, while the receiver demodulates the signal to recreate the original digital information. The goal is to produce a signal that can be transmitted easily and decoded reliably. Modems can be used with almost any means of transmitting analog signals, from LEDs to radio.
A mobile broadband modem, also known as wireless modem or cellular modem, is a type of modem that allows a personal computer or a router to receive wireless Internet access via a mobile broadband connection instead of using telephone or cable television lines. A mobile Internet user can connect using a wireless modem to a wireless Internet Service Provider (ISP) to get Internet access.
↑ Karl Willdig. "What You Need to Know about Modems". Fermilab Data Communications and Networking Group. Fermi National Accelerator Laboratory. Archived from the original on 2007-01-04. Retrieved 2008-02-18.
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