Rod Speed coughed up fur ball on Chris Mackenzie's plate about Austel
Approval and Modem

 CM>> but how do you know your modem hasn't done any damage ? just
 CM>> because your line is ok doesn't mean the exchange is
 CM>> undamaged.

 RS> If it keeps killing the line interface, you will find out Chris.
 RS> One obvious indication is that your phone line stops working.

Not quite although the physical line (cable) never changes it logical path
through the exchange is rarely the same for each call. In fact you could
call every day for a month and still not hit the same logical path, So in
essance if through some act of god a large voltage or somthing else goes
wrong with your modem then it is quite possible that you could kill one of
these logical paths and that in turn would look like an intermittent
problem.

 CM>> I was having a chat to the designer (netcomm) who is
 CM>> designing a new PCMCIA modem for netcomm and he said that in
 CM>> order to pass (one) Austel test modems are fried
 CM>> (electricaly) with about 12,000 vac and they must not pass
 CM>> any more than 200 vac down the phone line, if they do then
 CM>> they fail (and are not approved).

 RS> And non austel approved modems are normally FCC approved and that
 RS> requires them to pass a similar test with a lower voltage, which
 RS> is STILL perfectly adequate since it requires it to survive a
 RS> 1.5KV test.

perfectly adequate for WHO, You or AUSTEL ?
If it was adequate then why would Austel want another approval at a larger
voltage. Maybe because of the differing Locale.

 RS> And the phone exchange line interfaces have to
 RS> be able to survive lightning and stuff anyway.

There is currently NO WAY to design electrical equipment to survive a
lightning strike. The voltages and ampres are just too great for the
current components to handle.

 CM>> If telecom (telstra) get constant faults on one circuit (ie
 CM>> yours for instance) then they WILL search for a cause and
 CM>> trace it back to your line and come out to inspect your line,
 CM>> and if they find a non-austel approved modem (or other
 CM>> device) connected then they (austel) can give your a rather
 CM>> large (4 figure) fine and telstra would probably also take a
 CM>> dim view of it and charge you for repairs to the exchange
 CM>> circuit.

 RS> Yes, its theoretically possible. Pity that you cant actually
 RS> nominate too many non austel approved modems ever getting into
 RS> that situation tho. And the reason they dont is very very simple,
 RS> the FCC approval requirements are perfectly adequate to ensure
 RS> they dont kill the exchange.

See my above comment.

 RS> Even in a worst case scenario where your PC goes kaput and puts
 RS> the full 240V onto say the bus connector of the internal modem,
 RS> the 1.5KV voltage isolation to the phone line itself ensures no
 RS> 240V on the phone line.

 RS> Ditto with say an external modem if the plug pack fails and puts
 RS> 240V onto the modem. And if you are paranoid there is no reason
 RS> whatever why you cant use an Austel approved plug pack and a non
 RS> austel approved modem.

I can think of one reason strait away. Insurance, I wonder what the
insurance company would say if your $3000 pentium (for example) was toasted
by a non approved modem ?

Is it really worth the effort to save a few measily dollars (say $200) to
risk your expensive hardware ($2000 +) ?

Rgds, Chris

--- GoldED 2.42.G0214