ISDN Jack Installation
tedm at toybox.placo.com
Sat Sep 4 23:14:50 PDT 2004
Let me just clear up some misconceptions here on ISDN.
Dual channel dialup BRI ISDN is 128kbt/sec both directions, not 64k. ISDN
channels on either a BRI or PRI ISDN can be either voice, or data, or both.
a circuit-based, not a packet-based service, which makes it extremely
useful for certain applications. Videoconferencing being one of them.
It can also run an indefinite distance from the telephone central office,
because the CO can install repeaters on an ISDN line. Because the line
is a digital line, telephone calls over it have superior voice quality
than ones over an analog line.
ISDN isn't as popular for data use these days because it is not as
fast as cable or DSL. But, cable isn't in all areas and neither is
DSL. ISDN by contrast reaches something like 99% of the subscribers
in the United States. If your new house is out in the boondocks, ISDN
may be the only faster-than-dialup connection you can get.
ISDN PRI's delivered in the United States are delivered on T1 interfaces
and are typically not used in a home so I will say nothing further about
them. ISDN BRI circuits as delivered in the United States are delivered on
a single pair comprising a "U" interface. The only difference between an
jack and a regular Plain Old Telephone Service (POTS) jack in the U.S. is
ISDN jacks are RJ45 jacks, POTS jacks are RJ11. But the only reason that
telephone company uses RJ45 jacks is so that a telephone company technician
on site can immediately identify that the jack is a "special service" jack.
It is a telephone company standard to use RJ45 for anything that is not a
connection. There is absolutely no electrical requirement that ISDN uses
a RJ45 jack, and RJ11 jack will work fine. There is also no electrical
in the cable requirements for ISDN vs POTS. ISDN in the United States uses
exactly the same number of conductors in the cable as POTS so there is no
need to run extra pairs.
My advice to you since your having a house built is for your installer
to run plastic interduct to all the rooms for data cable. Interduct is like
a small flexible vacuum hose. It is very cheap. The usual procedure in a
home is to run regular old strings inside the interduct, run the interduct,
making sure to use large radius bends in the interduct,
then drywall. In this way if some idiot makes a mistake and drives a
nail or screw into the interduct it will not penetrate a cable. Once
the drywall is up, an installer can come along later and tie cables and
more string to the existing string, then pull the existing string to draw
the new cable and string through the interduct. Or if you do not want to
rig that particular room, you can just leave the string only in there
for future use. And even if the string breaks an installer can snake
a fishtape through the interduct to pull cable.
Run all the interduct in a hub-and-spoke fashion, with it all terminating
at a single location, such as the garage or utility closet. Make sure
that there is at least an electrical power outlet at that location, and
make sure that there is an interduct from that location to the telephone
company MPOE on the outside of the house.
Nobody knows what future cable will be designed and used. It is rather
foolish in my opinion to merely run cat-3 phone-grade cable or even cat-5
data-grade cable in a new house, when you can run interduct much cheaper
pull as many cables and as different types of cables as you need later on.
You may want to run tv cable, you may want to run alarm cable, in addition
to ethernet and voice cable.
> -----Original Message-----
> From: owner-freebsd-questions at freebsd.org
> [mailto:owner-freebsd-questions at freebsd.org]On Behalf Of Evan Sayer
> Sent: Saturday, September 04, 2004 2:53 PM
> To: freebsd-questions at freebsd.org
> Subject: ISDN Jack Installation
> My new house is currently being built, and I am wondering if I should
> install an ISDN jack now so that the SBC people don't have to do it
> once the walls are up and I actually want an ISDN connection. What do
> the people who install it have to do to get is upstairs when they
> install it, is it difficult? How is an ISDN line added, and can I do
> it myself? Thanks.
> freebsd-questions at freebsd.org mailing list
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