ISDN Information needed PLEASE


Senior member
Sep 5, 2003
If anyone has ANY information on ISDN please help me, Im looking at how they convert the line to digital and if they do it at each outlet


Golden Member
Oct 18, 1999
The signal is digital from the telco straight to your modem.

The connection from the telco actually starts out as a 144kbps connection. 16 Bits of that is reserved for D channel, then the connection gets partitioned into 2 64 bit B channels ( Bearer).

The B channels carry voice or data signals. The D channel carries signals between the ISDN modem/router and the telco CO. The two bearer plus one data channel is called the Basic Rate Interface (BRI). If you just had 1 64 B channel, it would be referred to as the Primary Rate Interface (PRI).

So in a nutshell, the connection is digital from Point A to B because the signal from the telco come out of an NT-1. It leaves the Telco as a 2 wire copper connection. Hits the NT1 via the location of the CO or property, depending how they have it setup for you, then split into 4 wire copper, which connects to your modem.


Platinum Member
Nov 26, 2001
not sure what you're asking for...

Basically you need your phone company to convert the line to ISDN, there's no way you're doing it yourself :p

First off they will test the line and make sure it's ok, chances are they'll find a bit of noise or something but nothing they cant fix. Worst that can happen is you have aluminium wiring or really rotten wire or something, isdn isnt 100% guaranteed, but chances are you should be able to get it. I mean, a LOT more likely than DSL. Once they check line is ok, they'll fiddle something at the telephone exchange (im in uk, might be a different where you are), turn off your phone and turn it back on, but this time the line will be setup for ISDN.

The phones and all phone sockets in your house will probably still work without the engineer having to do anything, they certainly will afterwards. You'll only have the digital ISDN connection at ONE specific socket, so make sure you know where you'll want your internet PC to be forever, before the engineer comes. The good news is it's likely (depending on your teleco) the engineer will install this socket anywhere you want him to, it'll lead off the "first" socket in your house (i.e. first socket from where the phone line comes into your house) but he should be able to wire in the ISDN socket wherever you like, aslong as it's not going to be too much of a pain to do the wiring -- I really doubt he'll do a "proper" job, keeping the wires within the walls etc, but will just staple the wire to the skirting board or whatever.

It might depend on however your teleco sets it up, but mine then installed an ISDN "modem" onto this socket. This is where your second phone line and ISDN connection plug into :). Mine has USB and ISDN cable sockets, yours may or may not have the USB. If you use the usb, you should be able to just plug it into your PC and with some software it'll work like that. If you use the cable though you'll need a ISDN terminal adapter, when I was looking around the STRONG reccomendation was for EICON Diva (quality) or some ASUS (cheap, reliable). If you are gaming, get the Eicon TA, if not, just use the USB if your provider gives you that.

Be warned, once ISDN is enabled apparently it becomes a fair bit harder to convert it for DSL, should it become available in your area (I presume it's not already because you'd be a loony to get ISDN instead of DSL). You can can use internet and have someone use the voice telephone at the same time, and can have either 64k or 128k internet - but the 128k is using "two lines" as far as your ISP is concerned, if you have a metered ISP you will pay for TWO lines -- that is for ISPs that even support multilinking, most dont. You might find a coupel of ISPs that have unmetered packages that do multilink, but they do cost like double the normal package (64k is normally same package as the 56k modemers).