Vic, I disagree on the reference pseudo ISDN and 56K as a an international standards committee crafted concept.
As early as 1968 AT&T had DSE (Data Switching Exchanges) which was operating at 56K. In 1972 the international community had a DSE like system with a maximum rate of 48K and the beginnings of X.1. X.1 did not support anything over 48K and was not finalized until 1984. There was not much support for 56K until long after 1972. This is back in the era of Jack Folts, SNA, the Datran/AT&T litigation and somewhat before ISO, X.25. A more accurate statement would be: "56K was the predecessor to ISDN." 56K has been kept alive due to phasing-in 64K into the 56K DSE network. This goes back to remarks I made in the past. If the system is working, sans problems, why replace it? "If it ain't broke don't fix it." The 56K systems were amortized to zero some time ago and are still generating revenue. Although not state of art are adequate for the present applications. ( I can just see all the technologists gritting their teeth and squirming in the chairs as they read this) Pseudo ISDN creates the perception 56K was something that copied ISDN, but at a lower rate. This is not the case, ISDN built upon the DSE 56K concept. Although poorly at best. I hope that's not too pedantic or detailed. Regards, Duane _______________________________________ On 9 May 1997, Victor L. Boersma wrote: > >From a practical perspective, yes. There was a lot of 56 Kbit stuff around > before ISDN was crafted by international standards committees. 56Kbit is not > ISDN, it is pseudo ISDN. > However, in a lot of places it is there, it works, and people are loath to > throw > it into the > garbage can. > > Ciao, > > Vic > >
