"Desk Rabbit" <spam-me-not@example.com> wrote in message
news:ZfOdnZUxW9Q9J5zVnZ2dnUVZ8saonZ2d@pipex.net...
> Gordon Henderson wrote:
> > In article <jir*9z+-r@news.chiark.greenend.org.uk>,
> > Theo Markettos <theom+news@chiark.greenend.org.uk> wrote:
> >
> >>Desk Rabbit <nospam@example.com> wrote:
> >>
> >>>What you need is one of these
> >>>http://networking.ringofsaturn.com/R...Portmaster.php
> >>
> >>A bit more than I wanted :) And doesn't it require a POTS or ISDN line
to
> >>operate?
> >>
> >>
> >>>Seriously though, what are you *actually* trying to achieve? If you
want
> >>>to connect to your PC then use any one of the many remote control
> >>>programs. Are you wanting to give a dialup service for clients and
> >>>customers? If so use one of the many free dialup numbers such as
> >>>http://www.adial.co.uk/
> >>>http://www.free-dialup.net/
> >>>http://www.nocostdialup.co.uk/
> >>
> >>'Free' dialup comes from the same school as 'unlimited' broadband - ie
it
> >>isn't. If you use it for anything more than trivial lengths of time you
end
> >>up with a very large phone bill.
> >>
> >>I'm wanting a dialup with a geographic number. I'm also wanting one
that
> >>doesn't become engaged or congested at busy times (which rules out
GeoISP
> >>and similar). It's an advantage for it to terminate in my network
because
> >>then I have control over onward routing, rather than at some random ISP.
Of
> >>course I could tunnel, but then I'd waste precious dialup bandwidth on
the
> >>encapsulation.
> >>
> >>Now it seems to me that an ATA is more complex than a modem, so I can't
see
> >>why the PSTN-Internet interface couldn't accommodate a modem too. And
get
> >>better rates than an analogue-analogue connection because a device
> >>synchronised to digital PSTN can do 56K.
> >
> >
> > I think you'll struggle to get 56K.
> Indeed. 56K back to back doesn't work. From Wikipedia:-

not quite - the test describes the ISP digital modems are doing the reverse
conversion.

what this is saying is 2 V.92? modems wont give you 56kbps back to back if
you go thru 2 analog to PCM conversions in between (ie modem ->analog
line -> PCM - analog -> modem).

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.
>
> "56k modems can only work at 56k if there is one pulse-code modulation
> to analog conversion in the path between the internet service provider's
> digital equipment and the user's modem. When this is not the case or
> when two 56k modems are used to communicate with each other they will
> generally fall back to 33.6 kbit/s using V.34 analog modulation. The 56
> kbit/s transmission exploits the fact that most telephone exchanges are
> interconnected with digital lines and so can use more efficient
> transmission techniques over twisted-pair lines."
>
> http://en.wikipedia.org/wiki/56k_modem
--
Regards

stephen_hope@xyzworld.com - replace xyz with ntl