Editing Twisted pair (section)

===Analog telephone===
Before digital communication and Ethernet became widespread there was no international standard for telephone cable. Standards were set at a national level. For instance, in the UK the [[General Post Office]] specified CW1293 and CW1308 cables. CW1308 was a similar specification to the earlier CW1293 but with an improved color code. CW1293 used mostly solid colors on the cores making it difficult to identify the pair it was twisted with without stripping back a large amount of sheath. To solve this problem. CW1308 has narrow rings of the paired color printed over the base color. Both cables are a similar standard to category 3 cable.<ref>{{citation |author=Stephen Roberts |title=Telephone Installation Handbook |pages=32–34 |publisher=Elsevier |date=2001 |isbn=0080521487}}</ref><ref>{{citation |author=Barry J. Elliot |title=Designing a Structured Cabling System to ISO 11801 |page=269 |publisher=CRC Press |date=2002 |isbn=0824741307}}</ref> Cables with categories 3 through 7 have 4 twisted pairs.<ref>{{cite book | url=https://books.google.com/books?id=d6nro_tNEpIC&dq=category+3+cable+pairs&pg=PA57 | isbn=978-0-08-049742-6 | title=Newnes Data Communications Pocket Book | date=19 April 2002 | publisher=Elsevier }}</ref>

Prior to the common use of polyethylene and other plastics for insulation, telephone twisted pair cable was insulated with waxed paper or cotton with a wax coating applied to the copper. The overall sheath of this type of cable was usually lead. This style of cable came into use in the late 19th century shortly after the invention of the telephone.<ref>''Telephony'', vol. 153, p. 118, Telephone Publishing Corporation 1957.</ref> The cable termination in termination boxes were sealed with molten wax or a resin to prevent the ingress of moisture which would seriously degrade the insulating properties of the paper insulation.<ref>''Paper Maker and British Paper Trade Journal'', vol. 83-84, p. 294, November 1, 1932 {{oclc|10634178}}</ref> However, such seals made future maintenance and changes more difficult. These cables are no longer made but are still occasionally encountered in old buildings and in various external areas, commonly rural villages.