In article ,
Ron Lowe writes:

2) The way analog telephony is carried over structured cabling could be
expanded a bit, it's not always the case that the ring signal is
re-generated at the LAU. There are 3 different types of LAU: PABX
master, PSTN master, and Secondary. This may be worth a bit of
explanation. It may be also be worth linking to this page:

http://www.evonet.com/evonet/index.asp?Page=102

I wouldn't even go so far as trying to pretend there are just two
standards for POTS over CAT5. We found at least 3 incompatible
LAUs at work -- it's basically each manuafcturer makes up their
own scheme, and make sure you use same manufacturer's LAUs at
both ends (which is a pain when you've ended up with 3 types
sprinkled around the site). The important thing is that the
A and B wired are on a pair, and assuming you don't want risk
of interference/crosstalk, the bell wire isn't carried over the
Cat 5 at all.

When I originally did my home structured cabling, I made a point
of putting A and B wires onto one of the pairs not used by
10/100 ethernet, so I didn't blow up any ethernet ports by
plugging in a POTS line by mistake. However, I'm not all gigabit
ethernet (uses all 4 pairs) so I just have to be more careful.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]