Editing Public data network (section)

== History ==
{{Further|Packet switching#X.25 era|X.25#How the CCITT standardized virtual circuits}}
Public packet switching networks came into operation in the 1970s. The first were [[Packet switching#RETD|RETD]] in Spain, in 1972;<ref>{{Cite web |last=Derek Barber |title=The Origins of Packet Switching |url=http://www.cs.man.ac.uk/CCS/res/res05.htm#f |access-date=2024-06-05 |website=Computer Resurrection Issue 5 |quote=The Spanish, dark horses, were the first people to have a public network. They'd got a bank network which they craftily turned into a public network overnight, and beat everybody to the post.}}</ref> the experimental [[Packet switching#RCP|RCP]] in France, also in 1972;<ref>{{cite conference |last=Després |first=R. |author-link=Rémi Després |year=1974 |title=RCP, the Experimental Packet-Switched Data Transmission Service of the French PTT |url=http://rogerdmoore.ca/PS/RCPDEP/RD.html |conference= |pages=171–185 |archive-url=https://web.archive.org/web/20131020142207/http://rogerdmoore.ca/PS/RCPDEP/RD.html |archive-date=2013-10-20 |access-date=2013-08-30 |book-title=Proceedings of ICCC 74 |url-status=dead}}</ref> [[Telenet]] in the United States, which began operation with proprietary protocols in 1975; [[Packet switching#EIN|EIN]] in the [[European Economic Community|EEC]] in 1976; and [[Packet Switch Stream|EPSS]] in the United Kingdom in 1976 (in development since 1969).<ref name=":02">{{Cite web |last1=Smith |first1=Ed |last2=Miller |first2=Chris |last3=Norton |first3=Jim |date=2017 |title=Packet Switching: The first steps on the road to the information society |url=https://www.npl.co.uk/getattachment/about-us/History/Famous-faces/Donald-Davies/UK-role-in-Packet-Switching-(1).pdf.aspx?lang=en-GB |access-date= |website=National Physical Laboratory}}</ref>

Telenet adopted [[X.25]] protocols shortly after they were published in 1976 while [[DATAPAC]] in Canada was the first public data network specifically designed for X.25, also in 1976.<ref name=":0" /> Many other PDNs adopted X.25 when they came into operation, including [[Transpac (network)|Transpac]] in France in 1978, [[Packet switching#Euronet|Euronet]] in the EEC in 1979, [[Packet Switch Stream]] in the United Kingdom in 1980, and [[AUSTPAC]] in Australia in 1982. [[Iberpac]] in Spain adopted X.25 in the 1980s. [[Tymnet]] and [[CompuServe]] in the United States also adopted X.25.

The [[International Packet Switched Service]] (IPSS) was the first commercial and international packet-switched network. It was a collaboration between British and American telecom companies that became operational in 1978.<ref>{{Cite journal|last=Roberts|first=L.G.|date=1978|title=The evolution of packet switching|journal=Proceedings of the IEEE|volume=66|issue=11|pages=1307–1313|doi=10.1109/PROC.1978.11141|s2cid=26876676|issn=1558-2256}}</ref><ref name=":0">{{Cite journal|last=Rybczynski|first=Tony|date=2009|title=Commercialization of packet switching (1975-1985): A Canadian perspective [History of Communications]|journal=IEEE Communications Magazine|volume=47|issue=12|pages=26–31|doi=10.1109/MCOM.2009.5350364|s2cid=23243636|issn=1558-1896}}</ref><ref>{{Cite journal|last=Schwartz|first=Mischa|date=2010|title=X.25 Virtual Circuits - TRANSPAC IN France - Pre-Internet Data Networking [History of communications]|journal=IEEE Communications Magazine|volume=48|issue=11|pages=40–46|doi=10.1109/MCOM.2010.5621965|s2cid=23639680|issn=1558-1896}}</ref>

The [[SITA (business services company)|SITA]] Data Transport Network for airlines adopted X.25 in 1981, becoming the world's most extensive packet-switching network.<ref name="history">{{cite web |title=SITA History |url=http://www.sita.aero/about-sita/what-we-do/sita-history |url-status=live |archive-url=https://web.archive.org/web/20120819091302/http://www.sita.aero/about-sita/what-we-do/sita-history |archive-date=19 August 2012 |accessdate=16 August 2012 |work=About SITA > What we do |publisher=SITA}}</ref><ref name=":11">{{Cite journal |last=Rybczynski |first=Tony |date=2009 |title=Commercialization of packet switching (1975–1985): A Canadian perspective [History of Communications] |journal=IEEE Communications Magazine |volume=47 |issue=12 |pages=26–31 |doi=10.1109/MCOM.2009.5350364 |s2cid=23243636}}</ref><ref>{{Cite web |title=Airline Control System |website=[[IBM]] |url=https://www.ibm.com/downloads/cas/OEYR6Y0X}}</ref>

The networks were interconnected with [[Gateway (telecommunications)|gateways]] using [[X.75]]. These combined networks had large global coverage during the 1980s and into the 1990s.<ref>{{harvnb|Davies|Bressan|2010|pp=[https://books.google.com/books?id=DN-t8MpZ0-wC&pg=PA2 2, 9]}}</ref><ref>{{cite thesis |last1=Ikram |first1=Nadeem |date=1985 |title=Internet Protocols and a Partial Implementation of CCITT X.75 |id={{OCLC|663449435|1091194379}} |url=https://www.proquest.com/openview/678d6e16a1f0ac0470e12db67623ce91/1 |page=2 |quote=Two main approaches to internetworking have come into existence based upon the virtual circuit and the datagram services. The vast majority of the work on interconnecting networks falls into one of these two approaches: The CCITT X.75 Recommendation; The DoD Internet Protocol (IP).}}</ref><ref>{{Cite journal |last1=Unsoy |first1=Mehmet S. |last2=Shanahan |first2=Theresa A. |date=1981 |title=X.75 internetworking of Datapac and Telenet |journal=ACM SIGCOMM Computer Communication Review |volume=11 |issue=4 |pages=232–239 |doi=10.1145/1013879.802679}}</ref>

Over time, other packet-switching technologies, including [[Frame Relay]] (FR) and [[Asynchronous Transfer Mode]] (ATM) gradually replaced X.25.<ref>{{Cite web |last=Titus |first=Tim |title=42 Dead Networking Technologies and What Killed Them |url=https://www.pathsolutions.com/blog/42-dead-networking-technologies |access-date=2023-09-23 |website=www.pathsolutions.com |language=en}}</ref>

Many of these networks later adopted [[Internet protocol suite|TCP/IP]] and provided the infrastructure for the early [[Internet]].<ref>{{Cite book |last1=Council |first1=National Research |url=https://books.google.com/books?id=Jh1pORpfvrQC&pg=PA148 |title=The Unpredictable Certainty: White Papers |last2=Sciences |first2=Division on Engineering and Physical |last3=Board |first3=Computer Science and Telecommunications |last4=Applications |first4=Commission on Physical Sciences, Mathematics, and |last5=Committee |first5=NII 2000 Steering |date=1998-02-05 |publisher=National Academies Press |isbn=978-0-309-17414-5 |language=en}}</ref><ref name="Schatt 1991 200">{{harv|Schatt|1991|p=200}}.</ref>