From: Vincent Cunniffe (vincent at domain cunniffe.net)
Date: Fri 18 May 2001 - 01:13:37 IST
Niall O Broin wrote:
> So, my working hypothesis is that there's more power in the telephone lines
> in Rathcoole, thus allowing for faster connections, but somehow screwing up
> old modems. As a hypothesis, it has the benefit of fitting the observed
> facts but I wonder does it have the benefit of being correct ? Anybody
> knowledgable care to comment ?
The specification for a perfect dialtone is, iirc, 50V on the phone
line. This is actually what Telecom engineers check when they forced
answer a complaint : if it's 50V they tell you the line's fine and then
they go away.
Now, not all lines actually get a good signal, and not all modems are
willing to accept a dialtone voltage of less than 50V. So, combine the
two, and you get a line which, while technically operable, might fall
below the recognition threshold of one particular piece of telecoms
equipment. This is why hanging multiple pieces of telecoms equipment off
a single socket can cause problems : faxes especially are bastards for
chomping a few volts off the line before passing it through to the phone
or the modem.
Use a slightly less picky modem, and you get a perfect connection. Move
the modem to somewhere where it can get it's required 50V signal, and
you'll get a perfect connection. Clear as mud ;-)
Regards,
Vin
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