Integrated Services Digital Network
A set of communications standards allowing a single wire or optical fibre to carry voice, digital network services and video. ISDN is intended to eventually replace the plain old telephone system. There are different kinds of ISDN connection of varying bandwidth:

DS0 = 1 channel PCM at 64 kbps
T1 or DS1 = 24 channels PCM at 1.54 Mbps
T1C or DS1C = 48 channels PCM at 3.15 Mbps
T2 or DS2 = 96 channels PCM at 6.31 Mbps
T3 or DS3 = 672 channels PCM at 44.736 Mbps
T4 or DS4 = 4032 channels PCM at 274.1 Mbps
All modern telephone exchanges are entirely digital systems, with the exception of the last mile to the customer's premesis.

ISDN is a last-mile solution to bring digital services right to the customer's door. This (in theory) should make for faster internet connectivity and provide ways around the limitations of an analogue phone line. In practice, it never took off because all telcos are instrinsically greedy and charge too much.

a bane of my existence. moving on....

ISDN Protocols
E - Applies to ISDN on an existing phone network.
I - Concepts, terminology, and services
Q - Switching and signaling

ISDN Function Groups
TE1 - Terminal Endpoint Device type 1. A BRI that understands ISDN standards.
TE2 - Predates ISDN standards. You have to use a TA (terminal adaptor) to generate BRI signals for a Cisco interface.

ISDN Reference Points
There are four different reference points to define logical interfaces between functional groupings such as TAs and NT1s.
R defines the reference point between non-ISDN equipment and a TA.
S defines the reference point between user terminals and an NT2.
T defines the reference point between the NT1 and line-termination equipment in a carrier network. This is only used in North America where the NT1 function isn't provided by the carrier network.

god, that's enough. I don't want to think about it....

After struggling with an ISDN system with a little (Thanks, Thomas!) help, I decided to put up this WU to help others out in case they decide to wire their casa with ISDN phone lines. This is just a simple description on how to wire the ISDN LAN.

The U-line

The POTS line you used with your old phones is dead to your dear old phones. Realize it and get on with your life. The 2-wire POTS line is now a U-line. The U-line is the line that carries multiple-bandwith data (Like ISDN and ADSL signals) to the phone central. A switch in the central makes your POTS line a U-line.

The NT box

No, not the nightmarish Microsoft OS, but a box that sit on your wall. This box takes the U-line signal, mixes it with AC power and produces the S/T-lines, or the actual phone lines. In short, it transforms the ISDN signals (Which can't travel very far) into the U-line signals. Actually, there are two NT boxes, but since the the other NT box is a part of your phone or ISDN TA (Modem), we'll just refer to this one as the NT box.

The NT box is powered at all times. The AC power supplies the phones in the ISDN chain with enough power to operate, some phones can't function without the power from the NT box.

Usually, the NT box has two lights. The amber light indicates AC power, while the green light indicates an correctly installed U-line.

  • Install your NT box in a nice discreet place, and run the U-line up to the box, or just place the box near your normal phone outlet.
  • Connect your old phone outlet to the LINE or U-LINE input of the NT box. The green light should be lit if the central office has switched your line to ISDN function. If not, check you connections, if they are OK, call the phone company because they haven't made the switch in the central office.
  • Connect the AC power, the amber light will light up. If not, something is seriously wrong. Check the AC outlet with a lamp or something, check you wiring. If this is OK, exchange the NT box.

The ISDN outlet

OK. The NT box is glowing like a cheap Christmas tree, and the ISDN phone is waiting... If you don't want to establish an ISDN network, just plug in the phone and you're set. You may have to program the phone; look up that in the phone manual.

The ISDN network

Making a ISDN network isn't as easy as ethernet. You want to have a CAT-5 cable and use two of the pairs. This network is called an S0 bus, don't be scared of the sci-fi-like name; it is easy to understand after some years...

All cool and old-school networks use termination. There are two ways to terminate an ISDN bus:

  • Using Arnold Schwarzenegger
  • Using 50/100 Ohm resistors
Since Arnie is expensive to hire, we'll use resistors. I recommend buying ISDN outlets with resistors welded on the circuit board. If you're reading this manual to understand how to build the S0 net, that's your sign to buy those. The network (Ooh, your phones have suddenly become quite advanced!) need to be terminated at both ends. The NT box has DIP switches inside. When these are in the ON positions, the box is a terminated end. That means that you can strech the S0 line up to 100 meters to connect your phone. You need to remember that the other end has to be terminated as well. This is where the pre-terminated ISDN outlet comes in handy.

Put up the cable and crimp on all wires on the RJ45 plug, even if only the two pairs in the middle are used. The RJ45 plug goes in the "ISDN out" jack on the NT box.

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This is what your crimped RJ45 plug looks like; the locking tab is on the reverse side. Make a note of what colours the 3, 4, 5 and 6 use. Now:

Cable 4 from the plug goes to 5 on the outlet.
Cable 5 from the plug goes to 4 on the outlet.
Cable 3 from the plug goes to 6 on the outlet.
Cable 6 from the plug goes to 3 on the outlet.

BE CAREFUL TO NOT SHORT PAIRS 4/3 and 5/6!

That's it! Remember to turn on the termination on the LAST outlet, and activate the emergency power function on at least one phone in case of an AC power loss in your house.

/msg me any corrections...

Album: ISDN
Artist: The Future Sound of London
Label: Virgin Records Ltd
Released: 1995
Summary: Eerie, like walking through an abandoned city.

There are three versions of ISDN, a limited edition version which came out the same year as Lifeforms, and innocuous looking CD and vinyl versions that followed a year later. I managed to get my hands on the regular CD version.

Like its predecessor, ISDN's general vibe is still otherworldly and it still oozes atmosphere, especially in its mellow, laid back cuts such as Smokin' Japanese Babe and Eyes Pop - Skin Explodes - Everybody Dead. There are plenty of haunting melodies, although not as many as in Lifeforms, and there's The Future Sound of London's typical plethora of homegrown synthetic sound effects and sampled film dialogue.

The overall tone, however, is much darker. ISDN sounds scary, desolate, old and decaying, putting it in stark contrast to the beautiful, shimmering jungle fragments of Lifeforms. While you could marvel at the previous album's ethereal beauty, ISDN is more like a trip through an abandoned, deserted urban sprawl.

The atmospheric pieces are joined by a handful of loud, beat driven tracks such as Slider and the 6/4 time The Far Out Son of Lung and the Ramblings of a Madman. This makes ISDN bridge the gap between Lifeforms and the group's next album, Dead Cities, rather nicely, easing you into the group's less ambient later style.

Overall, ISDN isn't as beautiful as Lifeforms or as catchy as Dead Cities, but it has enough substance to be of interest to people who already enjoy both and still want more.

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