TELECOM Digest OnLine - Sorted: Re: Physically Protecting The Local Loop Metwork?

Re: Physically Protecting The Local Loop Metwork?

John C. Fowler (
Sun, 18 Dec 2005 19:11:16 PST

Lisa Hancock wrote:

> Today customers own all their equipment that is supposed to be
> certified. But what happens if the customer alters the equipment or
> it is defective? What happens if a high voltage is sent out
> accidently over a telephone line (ie house current, either 110 or
> 220, or ringing current meant for an extension telephone of a PBX)?

In the United States, customers are not supposed to connect anything
to the Public Switched Telephone Network unless it conforms to FCC
Part 68 (see for details).
This is supposed to guarantee that the device does not create problems
for the network or other customers on it.

So what happens if you ignore that, and attach house current to the
phone line? This would likely blow a fuse somewhere. If not, the
alternative would be for the phone wires to catch/start a fire, as
they usually aren't of a sufficient gauge for that kind of current.

If you were to connect something that didn't blow a fuse but caused
problems for other subscribers, they could file a formal complaint
with the FCC against you, assuming they could figure out who you were.

I think I remember once seeing a little circuit board that did nothing
except guarantee Part 68 compliance. (It even had its own Ringer
Equivalence Number, a whole 0.0B.) It was designed for people who
wanted to attach their own homebrew projects to the phone line but not
worry about causing problems. I don't remember where I saw it, sorry,
but you could probably find something like it wherever you buy other
bare electronic circuit thingies.

John C. Fowler,

Post Followup Article Use your browser's quoting feature to quote article into reply
Go to Next message: Howard S. Wharton: "Re: USO Asking For Christmas Help"
Go to Previous message: DevilsPGD: "Re: Cell Phone to Land Line"
May be in reply to: "Physically Protecting The Local Loop Metwork?"
Next in thread: Scott Dorsey: "Re: Physically Protecting The Local Loop Metwork?"
TELECOM Digest: Home Page