A little history on ISDN, if you please. One reason that ISDN never found wide acceptance in the US was the fact that it was developed under the auspices of the CCITT (precursor to the ITU-T), driven by the PTTs of Europe. Beginning in 1961 Study Group III went about laying down restrictive rules for every conceivable issue associated with private leased circuits. They wanted to restrict the use of private lines so as to effectively force users to switched services, which were much more lucrative to the administrations (PTTs). Google on "leased circuits were generally to be made available" to bring up a couple of pages (from Google Books) of a book entitled "Regulating the Global Information Society". Pages 143-144 show a list of 17 restrictions on the use of private leased circuits. Page 145 has a stinging evaluation that says, in part, "discouragement [of private leased lines] would seem to stem . . . from a fear that their proliferation constitutes a threat to the revenues or even the status of administrations." It goes on to say "[to develop] unrealistic tariffs and a maze of loosely worded Recommendations, against whose restrictive interpretation users would have little redress, is to disregard the canons of social justice and of conventional business conduct. Furthermore, it is retarding the development of telecommunications in the service of man."
On page 145 we find "They (the CCITT, driven by the European PTTs) also sought to strengthen their hand by developing the Integrated Services Digital Network, or ISDN. The ISDN was conceived in the1973-6 study period as a single integrated national high-speed network that could carry all traffic regardless of its technical requirements. The vision was that with such networks in place, administrations' public networks could handle all business requirements for advanced services, potentially obviating the need to lease lines". The PTTs did (grudgingly) permit private lines for "closed user groups" such as the SITA airline network and the SWIFT banking network.
On page 146 we read that the Director of the CCITT stated in a letter to the FCC that "It seems to me an extremely dangerous situation when one country, and what is more, the leading country with regard to the number of subscribers, the extent of its services and its telecommunications technology, can help to undermine the work of the CCITT." (emphasis mine).
So the bottom line, the way I understand it, was that the Europeans wanted to do everything they could to prohibit private lines and force all services to ISDN. The United States wanted to open up the market, and in fact, the US Trade Representative began discussions with the telecom industry that ultimately led to making telecommunications a "trade" issue that became a part of the 1986-94 Uruguay Round of trade negotiations that resulted in the World Trade Organization that we have today.
William Drake's paper (cited above) used to be posted to the internet, but now it seems to be available only as a part of the larger book "Regulating the Global Information Society" Edited by Christopher T. Marsden.
Charles G. Gray Senior Lecturer, Telecommunications Oklahoma State University - Tulsa (918) 594-8433