[ILUG] OT - Modem mystery

[Vincent Cunniffe]

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