Dial-up Internet access
From Wikipedia, the free encyclopedia
Dial-up Internet access is a form of Internet access via telephone lines.[1] The user's computer or router uses an attached modem connected to a telephone line to dial into an Internet service provider's (ISP) node to establish a modem-to-modem link, which is then used to route Internet Protocol packets between the user's equipment and hosts on the Internet.The term was coined during the early days of computer telecommunications when modems were needed to connect dumb terminals or computers running terminal emulator software to mainframes, minicomputers, online services and bulletin board systems via a telephone line.
[edit] Availability
Dial-up connections to the Internet require no infrastructure other than the telephone network. As telephone access is widely available, dial-up remains useful to travelers. Dial-up is usually the only choice available for rural or remote areas where broadband installations are not prevalent due to low population and demand. Dial-up access may also be an alternative for users on limited budgets as it is offered for 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 usable telephone connection (several seconds, depending on the location) and perform handshaking 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 or the ISP terminates the connection. Internet service providers will often set a limit on connection durations to prevent hogging of access, 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 days. This is particularly useful for downloading large files such as videos.A 2008 Pew Internet and American Life Project study states that only 10 percent of American adults still use dial-up Internet access. Reasons for retaining dial-up access span from lack of infrastructure to high broadband prices. [2]
[edit] Performance
Modern dial-up modems typically have a maximum theoretical transfer speed of 56 kbit/s (using the V.90 or V.92 protocol), 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.Dial-up connections usually have latency as high as 400 ms or even more, which can make online gaming or video conferencing difficult, if not impossible. First person shooter style games are the most sensitive to latency, making playing them impractical on dial-up. However, some games such as Star Wars: Galaxies, The Sims Online, Warcraft 3, Guild Wars, Unreal Tournament, Halo: Combat Evolved, and Audition are capable of running on 56k dial-up.An increasing amount of Internet content such as streaming media will not work at dialup speeds.
[edit] References
- ^ "Dial-Up Technologies". Cisco Documentation. Cisco Systems, Inc.. http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/dialup.htm. Retrieved on 2008-02-18.
- ^ "Broadband Internet? No thanks". Associated Press. CNN. http://www.cnn.com/2008/TECH/ptech/07/02/broadband.study.ap/index.html. Retrieved on 2008-07-03.
