Hi Pete,
>Hello Kali,
>I have an interest in electronics and I am curious about your floating
>'phone lines. Can you tell me, how many volts DC are typically present,
>relative to Earth? Also, do manufacturers offer special modems which can
>handle this DC offset?
>Pete
All phone lines, from all parts of the world, including the USA,
should be treated as fully-floating. In virtually all cases they are,
although in some cases the DC offset may be small. The AC impedance
to ground from either leg is very high.
All modems are designed to maintain the balanced and floating conditions.
Try touching an earth to one of your phone lines during a conversation
and see what happens.
Mike
(Telephone equipment designer. :)
