In article <iHkMj.79571$5i5.38214@newsfe6-gui.ntli.net>,
stephen <stephen_hope@xyzworld.com> wrote:
[color=blue]
>obviously there is kit that can cope with 1 conversion, since all those old
>modem dial in banks run by ISPs did exactly that - although they had to
>hooked up in a particular way to make it work.[/color]

They went by various names - eg. Livingston Portmonster, or "not
modems" .... They plumbed into the PSTN via E1 / ISDN30 lines and took
the data digitally with no intervening analogue conversion stage, other
than the modem at the customers end. (hence the term "not modem") They
did clever DSP type work internally to recreate the original digital
data out of the digitally encoded analogue data, ran the other end of
the (usually) PPP link, then presented it as an IP connection out on an
Ethernet line.

Gordon