Editing ISDN (section)

=== Standardization ===

Around 1978, Ralph Wyndrum, Barry Bossick and Joe Lechleider of [[Bell Labs]] began one such effort to develop a last-mile solution. They studied a number of derivatives of the T1's AMI concept and concluded that a customer-side line could reliably carry about {{nowrap|160 kbit/s}} of data over a distance of {{convert|4|to|5|miles}}. That would be enough to carry two voice-quality lines at {{nowrap|64 kbit/s}} as well as a separate {{nowrap|16 kbit/s}} line for data. At the time, [[modem]]s were normally {{nowrap|300 bit/s}} and {{nowrap|1200 bit/s}} would not become common until the early 1980s and the {{nowrap|2400 bit/s}} standard would not be completed until 1984. In this market, {{nowrap|16 kbit/s}} represented a significant advance in performance in addition to being a separate channel that coexists with voice channels.{{sfn|Cioffi|2011|p=31}}

A key problem was that the customer might only have a single twisted pair line to the location of the handset, so the solution used in T1 with separate upstream and downstream connections was not universally available. With analog connections, the solution was to use [[echo cancellation]], but at the much higher bandwidth of the new concept, this would not be so simple. A debate broke out between teams worldwide about the best solution to this problem; some promoted newer versions of echo cancellation, while others preferred the "ping pong" concept where the direction of data would rapidly switch the line from send to receive at such a high rate it would not be noticeable to the user. [[John Cioffi]] had recently demonstrated echo cancellation would work at these speeds, and further suggested that they should consider moving directly to {{nowrap|1.5 Mbit/s}} performance using this concept. The suggestion was literally laughed off the table (His boss told him to "sit down and shut up"{{sfn|Cioffi|2011|p=31}}) but the echo cancellation concept that was taken up by Joe Lechleider eventually came to win the debate.{{sfn|Cioffi|2011|p=31}}

Meanwhile, the debate over the encoding scheme itself was also ongoing. As the new standard was to be international, this was even more contentious as several regional digital standards had emerged in the 1960s and 70s and merging them was not going to be easy. To further confuse issues, in 1984 the [[Breakup of the Bell System|Bell System was broken up]] and the US center for development moved to the [[American National Standards Institute]] (ANSI) T1D1.3 committee. Thomas Starr of the newly formed [[Ameritech]] led this effort and eventually convinced the ANSI group to select the [[2B1Q]] standard proposed by Peter Adams of [[British Telecom]]. This standard used an 80&nbsp;kHz base frequency and encoded two bits per baud to produce the {{nowrap|160 kbit/s}} base rate. Ultimately Japan selected a different standard, and Germany selected one with three levels instead of four, but all of these could interchange with the ANSI standard.{{sfn|Cioffi|2011|p=32}}

From an economic perspective, the [[European Commission]] sought to liberalize and regulate ISDN across the [[European Economic Community]].<ref>{{cite journal |first=Reinhard |last=Schulte-Braucks |title=Telecommunications Law and Policy in the European Community |volume=13 |journal=[[Fordham International Law Journal|Fordham Int'l L.J.]] |page=234 |date=1989 |url=https://ir.lawnet.fordham.edu/ilj/vol13/iss2/5 |issue=2 |access-date=2022-10-18}}</ref> The [[Council of the European Communities]] adopted Council Recommendation [https://eur-lex.europa.eu/eli/reco/1986/659 86/659/EEC]<ref>{{Webarchive|url=https://web.archive.org/web/20221018042541/https://eur-lex.europa.eu/eli/reco/1986/659 |date=2022-10-18 }}</ref> in December 1986 for its coordinated introduction within the framework of CEPT. [[ETSI]] (the European Telecommunications Standards Institute) was created by CEPT in 1988 and would develop the framework.