Editing Telephone (section)

== Digital telephones and voice over IP ==
{{Main|Digital telephony|Voice over IP}}
[[File:CiscoIPPhone7941Series.jpg|thumb|An IP desktop telephone attached to a computer network]]
[[File:Fixed telephone lines per 100 inhabitants 1997-2007 ITU.png|thumb|upright=1.35|Fixed telephone lines per 100 inhabitants 1997–2007]]

The invention of the [[transistor]] in 1947 dramatically changed the technology used in telephone systems and in the long-distance transmission networks, over the next several decades. With the development of [[stored program control]] and [[MOS integrated circuit]]s for [[electronic switching system]]s, and new transmission technologies such as [[pulse-code modulation]] (PCM), [[telephony]] gradually evolved towards [[digital telephony]], which improved the capacity, quality, and cost of the network.<ref name="Allstot">{{cite book |last1=Allstot |first1=David J. |chapter=Switched Capacitor Filters |editor-last1=Maloberti |editor-first1=Franco |editor-last2=Davies |editor-first2=Anthony C. |title=A Short History of Circuits and Systems: From Green, Mobile, Pervasive Networking to Big Data Computing |date=2016 |publisher=[[IEEE Circuits and Systems Society]] |isbn=9788793609860 |pages=105–110 |url=https://ieee-cas.org/sites/default/files/a_short_history_of_circuits_and_systems-_ebook-_web.pdf |access-date=2019-11-29 |archive-date=2021-09-30 |archive-url=https://web.archive.org/web/20210930151716/https://ieee-cas.org/sites/default/files/a_short_history_of_circuits_and_systems-_ebook-_web.pdf |url-status=dead }}</ref>

[[Integrated Services Digital Network|Integrated Services Digital Network (ISDN)]] was launched in the 1980's, providing businesses and consumers with access to digital telephony services such as data, voice, [[Videotelephony|video]], and [[fax]] services.<ref>{{Cite web |title=What is ISDN - Essentials Guide » Electronics Notes |url=https://www.electronics-notes.com/articles/connectivity/isdn/what-is-isdn.php |access-date=2022-08-28 |website=www.electronics-notes.com |archive-date=2022-08-28 |archive-url=https://web.archive.org/web/20220828000053/https://www.electronics-notes.com/articles/connectivity/isdn/what-is-isdn.php |url-status=live }}</ref>

The development of digital [[data communication]]s methods made it possible to digitize voice and transmit it as real-time data across [[computer network]]s and the [[Internet]], giving rise to the field of Internet Protocol (IP) telephony, also known as [[voice over Internet Protocol]] (VoIP). VoIP has proven to be a [[disruptive technology]] that is rapidly replacing traditional telephone network infrastructure.<ref>{{Cite web |title=VoIP is winning over a variety of phone users |url=https://www.orlandosentinel.com/news/os-xpm-2006-09-18-cover18-story.html |access-date=2022-08-25 |website=Orlando Sentinel |date=18 September 2006 |archive-date=2022-08-30 |archive-url=https://web.archive.org/web/20220830210203/https://www.orlandosentinel.com/news/os-xpm-2006-09-18-cover18-story.html |url-status=live }}</ref>

By January 2005, up to 10% of telephone subscribers in Japan and [[South Korea]] had switched to this digital telephone service. A January 2005 [[Newsweek]] article suggested that Internet telephony may be "the next big thing."<ref>{{cite web|last=Sheridan |first=Barrett |url=http://msnbc.msn.com/id/6831938/site/newsweek/ |title=Newsweek – National News, World News, Health, Technology, Entertainment and more... |publisher=MSNBC |access-date=2010-05-23 |url-status=dead |archive-url=https://web.archive.org/web/20050118033848/http://msnbc.msn.com/id/6831938/site/newsweek/ |archive-date=January 18, 2005 }}</ref> The technology has spawned a new industry comprising many VoIP companies that offer services to [[consumer]]s and [[business]]es. The reported global VoIP market in October 2021 was $85.2 billion with a projection of $102.5 billion by 2026.<ref>{{Cite journal|date=October 2021|title=Global VoIP Services Market 2021-2026|url=https://www.researchandmarkets.com/reports/5457497/global-voip-services-market-2021-2026|journal=Research and Markets|via=|access-date=2021-12-04|archive-date=2021-12-04|archive-url=https://web.archive.org/web/20211204200158/https://www.researchandmarkets.com/reports/5457497/global-voip-services-market-2021-2026|url-status=live}}</ref>

IP telephony uses high-bandwidth Internet connections and specialized customer premises equipment to transmit telephone calls via the Internet, or any modern private data network. The customer equipment may be an [[analog telephone adapter]] (ATA) which translates the signals of a conventional analog telephone; an [[IP Phone]], a dedicated standalone device; or a computer [[softphone]] application, utilizing the microphone and headset devices of a personal computer or smartphone.<ref>{{Cite web |title=VoIP Equipment Guide 2022: Types of Hardware + Top Manufacturers |url=https://getvoip.com/blog/2020/10/27/voip-equipment/ |access-date=2022-08-25 |website=getvoip.com |language=en-US}}</ref>

In recent years, VoIP technology has evolved to integrate with [[Cellular network|mobile networks]], including Voice over LTE ([[VoLTE]]) and Voice over 5G ([[Vo5G]]), enabling seamless voice communication over mobile data networks. These advancements have made VoIP not only a primary method for Internet-based communication but also a central feature of modern [[Mobile telephony|mobile communication]] infrastructure.<ref>{{Cite web |title=Communication services (VoLTE/VoNR) |url=https://www.3gpp.org/technologies/volte-vonr |access-date=2024-11-30 |website=www.3gpp.org |archive-date=2024-12-02 |archive-url=https://web.archive.org/web/20241202195917/https://www.3gpp.org/technologies/volte-vonr |url-status=live }}</ref>

While traditional analog telephones are typically powered from the central office through the telephone line, digital telephones require a local power supply.<ref>{{Cite web |date=2011-09-15 |title=VoIP Phone System Battery Backups {{!}} voipreview.org |url=https://www.voipreview.org/blog/voip-phone-system-battery-backups |access-date=2022-08-25 |website=VoipReview |language=en-us |archive-date=2022-08-08 |archive-url=https://web.archive.org/web/20220808093927/https://www.voipreview.org/blog/voip-phone-system-battery-backups |url-status=live }}</ref> Internet-based digital service also requires special provisions to provide the service location to the emergency services when an [[emergency telephone number]] is called.<ref>{{Cite web |date=2011-05-26 |title=VoIP and 911 Service |url=https://www.fcc.gov/consumers/guides/voip-and-911-service |access-date=2022-08-25 |website=Federal Communications Commission |language=en |archive-date=2022-08-11 |archive-url=https://web.archive.org/web/20220811094019/https://www.fcc.gov/consumers/guides/voip-and-911-service |url-status=live }}</ref>