From: William Levak (wlevak_at_cyberspace.org)
Date: 2004-01-29 01:23:24
On Wed, 28 Jan 2004, Groepaz wrote:
> On Wednesday 28 January 2004 06:25, William Levak wrote:
> > >Hi All,
> > >
> > >I've received a few of these and before plugging into the Australian
> > >telephone system - and having Telstra issue me a bill for $$$$ damages -
> > >I was wondering how universal these modems were. Was the modem different
> > >for different markets? The ones I have came from the USA.
> >
> > As far as I know, telephones everywhere are very much the same, with some
> > slight timing differences.
> >
> > In North America, the dial pulse is +90 V, and the voice signal is -48 V
> > at 21 to 35 mA. You should be able to measure these with a volt meter.
>
> wow 48v ? that sounds a bit much :) afaik its ~60ac for letting the phone
> ring, but its ~12vdc for voice...
That's maximun values. Most equipment will work at lower levels.
If your equipment puts out a 60 V dial pulse and 12 V voice, it should not
damage the phone company's equipment. If, on the other hand, The phone
company uses 60 V dial and 12 V voice, and the modem puts out 90 V dial
and 48 V voive, you have a problem.
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