Editing Digital subscriber line (section)

{{Short description|Family of technologies that are used to transmit digital data over telephone lines}}
{{Redirect|DSL}}

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'''Digital subscriber line''' ('''DSL'''; originally '''digital subscriber loop''') is a family of technologies that are used to transmit [[digital data]] over [[telephone line]]s.<ref>{{cite web | url=https://books.google.com/books?id=fFrjSBw0w14C&dq=dsl+voice+grade&pg=PA230 | title=PC Mag | date=10 February 1998 }}</ref> 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 ADSL, the data throughput in the [[upstream (networking)|upstream]] direction (the direction to the service provider) is lower, hence the designation of ''asymmetric'' service. In [[symmetric digital subscriber line]] (SDSL) services, the downstream and upstream data rates are equal.

DSL service can be delivered simultaneously with [[plain old telephone service|wired telephone service]] on the same telephone line since DSL uses higher [[frequency band]]s for data transmission. On the customer premises, a [[DSL filter]] is installed on each telephone to prevent undesirable interaction between DSL and telephone service.

The [[bit rate]] of consumer ADSL services typically ranges from {{val|256|ul=kbit/s}} up to {{val|25|ul=Mbit/s}}, while the later VDSL+ technology delivers between {{nowrap|16 Mbit/s}} and {{nowrap|250 Mbit/s}} in the direction to the customer ([[downstream (networking)|downstream]]), with up to {{nowrap|40 Mbit/s}} upstream. The exact performance is depending on technology, line conditions, and service-level implementation. Researchers at [[Bell Labs]] have reached SDSL speeds over {{nowrap|1 Gbit/s}} using traditional copper telephone lines, though such speeds have not been made available for the end customers yet.<ref>{{cite web |last=Owano |first=Nancy |date=10 July 2014 |title=Alcatel-Lucent sets broadband speed record using copper |url=http://phys.org/news/2014-07-alcatel-lucent-broadband-copper.html |website=Phys.org}}</ref><ref>{{cite web |last=Brian |first=Matt |date=10 July 2014 |title=Researchers get record broadband speeds out of old-school copper wire |url=https://www.engadget.com/2014/07/10/alcatel-lucent-broadband-copper-world-record/ |website=Engadget}}</ref><ref>{{cite web|url=https://gizmodo.com/the-next-generation-of-dsl-can-pump-1gbps-through-coppe-1484256467|title=The Next Generation of DSL Can Pump 1Gbps Through Copper Phone Lines|website=Gizmodo|date=18 December 2013|first=Andrew|last=Tarantola}}</ref><!--see [[G.fast]] for additional support-->