Telephone line

Utility pole with electric lines (top) and telephone cables.
Fixed telephone lines per 100 inhabitants, 1997–2007.
Cross section of telephone cable of 1,800 twisted pairs, 1922.

A telephone line or telephone circuit (or just line or circuit industrywide) is a single-user circuit on a telephone communication system.[1] It is designed to reproduce speech of a quality that is understandable.[2] 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 billing purposes reserved for that user.

Telephone lines are used to deliver landline telephone service and digital subscriber line (DSL) phone cable service to the premises.[3] Telephone overhead lines are connected to the public switched telephone network.[4][5] The voltage at a subscriber's network interface is typically 48 V between the ring and tip wires, with tip near ground and ring at –48 V.

  1. ^ Telephones. U.S. Government Printing Office. 1910.
  2. ^ "Telephone Circuits". ScienceDirect. Retrieved 2022-12-12.
  3. ^ Pizzi, Skip; Jones, Graham (2014-04-24). A Broadcast Engineering Tutorial for Non-Engineers. CRC Press. p. 18. ISBN 978-1-317-90683-4.
  4. ^ Staff, Cia Training Ltd (2003-04-01). Ecdl/Icdl Syllabus 4 Module 1 Basic Concepts of IT: European Computer Driving Licence. CIA Training Ltd. p. 35. ISBN 978-1-86005-123-4.
  5. ^ "Get phone number from Facebook". lucidgen.com (in Vietnamese). 2019-04-28. Retrieved 2024-08-15.