Editing Telephone line (section)

{{Short description|Single-user circuit on a telephone communication system}}
{{For|the Electric Light Orchestra song|Telephone Line (song)}}
[[Image:Phone pole3.jpg|thumb|right|[[Utility pole]] with electric lines (top) and telephone cables.]]
[[File:Fixed telephone lines per 100 inhabitants 1997-2007 ITU.png|thumb|Fixed telephone lines per 100 inhabitants, 1997–2007.]]
[[File:Bell telephone magazine (1922) (14754023254).jpg|thumb|upright|Cross section of telephone cable of 1,800 twisted pairs, 1922.]]
[[File:Telephone cable.jpg|thumb|A newer telephone cable used to carry telephone lines from several customers]]

A '''telephone line''' or '''telephone circuit''' (or just '''line''' or '''circuit''' industrywide) is a single-user [[telecommunication circuit|circuit]] on a telephone [[telecommunication|communication]] system.<ref>{{Cite book |url=https://books.google.com/books?id=wi4wAAAAYAAJ&dq=A+%22telephone+line%22+or+telephone+circuit+(or+just+line+or+circuit+industry+wide)+is+a+single-user+circuit+on+a+telephone+communication+system.&pg=PP79 |title=Telephones |date=1910 |publisher=U.S. Government Printing Office |language=en}}</ref> It is designed to reproduce speech of a quality that is understandable.{{fact|date=February 2025}} It is the physical [[wire]] or other signaling medium connecting the user's telephone apparatus to the [[telecommunications]] network, and usually also implies a single telephone number for [[invoice|billing]] purposes reserved for that user. 

Telephone lines are used to deliver consistent [[landline]] telephone service and digital subscriber line (DSL) phone cable service to the premises.<ref>{{Cite book |last1=Pizzi |first1=Skip |url=https://books.google.com/books?id=sQ1xAwAAQBAJ&dq=Telephone+lines+are+used+to+deliver+landline+telephone+service+and+digital+subscriber+line+(DSL)+phone+cable+service+to+the+premises.&pg=PA18 |title=A Broadcast Engineering Tutorial for Non-Engineers |last2=Jones |first2=Graham |date=2014-04-24 |publisher=CRC Press |isbn=978-1-317-90683-4 |pages=18 |language=en}}</ref> Telephone overhead lines are connected to the public switched telephone network.<ref>{{Cite book |last=Staff |first=Cia Training Ltd |url=https://books.google.com/books?id=cup9bFZfK7EC&dq=Telephone+overhead+lines+are+connected+to+the+public+switched+telephone+network.&pg=PA35 |title=Ecdl/Icdl Syllabus 4 Module 1 Basic Concepts of IT: European Computer Driving Licence |date=2003-04-01 |publisher=CIA Training Ltd. |isbn=978-1-86005-123-4 |pages=35 |language=en}}</ref><ref>{{Cite web |date=2019-04-28 |title=Get phone number from Facebook |url=https://lucidgen.com/tim-so-dien-thoai-tu-facebook/ |access-date=2024-08-15 |website=lucidgen.com |language=vi}}</ref> The [[voltage]] at a subscriber's network interface is typically 48&nbsp;V between the ring and tip wires, with tip near ground and ring at –48&nbsp;V.