What Was ISDN?

The 56k modem was a quasi-digital connection and as I recall asymmetric.

xDSL (there were so many flavors) was a disappointment in some areas in comparison to ISDN for reasons I do not recall, but I think it had to do with the fact that it often shared the copper with POTS. xDSL on former ISDN lines or in buildings wired for xDSL was far more performant. DOCSIS was generally good.

Also, modems and ISDN, owing to their switched nature, could be used to connect to services other than the Internet. xDSL and especially DOCSIS was Internet only AFAIR.

In the end I was stuck on modem until DSL finally rolled out in my area. One thing I miss about DSL was that it was open. You had your choice of several competing ISPs that offered service over the same lines. You could get some very nice fast service with lots of features for cheap. Locally run Usenet servers. Free web hosting. Free terminal server. Free Email. Static IP addresses. All the stuff that the monopolies don't offer anymore.

In Australia, we had an ISDN2 product (BRI) which gave us that 128Kbps bitstream. Hardware boxes from brands like Musicam Prima, Tieline and Comrex would allow transmitting a bi-directional MPEG2 audio stream. When I used to dial these things, you’d hear a low-bitrate stream first for a few seconds before the 2nd number would dial and you’d get that full 128Kbps. Different brands of codecs were theoretically interoperable, subject to the settings and codecs matching. I remember the Tieline codecs probably sounded best because they had their ‘MusicPlus’ codec (which I think was actually AAC+ under the hood). But most other codecs were only MPEG2, so you were stuck with that.

We used to use these for outside broadcasts, backup links between the studios and transmitter site, and links to other broadcasters (e.g. the TV news presenter dialing in to tease the nightly news headlines).

Even after the internet was well and truly established, ISDN was still used a lot for this because it was ‘standardised’ and also a pretty much guaranteed bitrate - whereas ADSL might give you a couple of megabits but with no guarantee you’d have that between your two locations at all times. When you need low latency two way conversations, you can’t just dial up the latency and keep re-transmitting packets until they arrive.

The local telco used to be able to install these fairly easily on a temporary basis so you could do a broadcast from a temporary location (e.g. local advertiser books a broadcast at their store). You couldn’t really get a temporary internet connection put in at the time. You could get stereo audio both directions, but often you’d use the left channel for your program audio, and the right channel for an intercom in everyone’s earpieces. So long as you played the music from the studios and just fed the mics down the ISDN from the remote location, the quality was passable.

We also had ISDN10/20/30 (PRI) for general telephony. I interfaced these to SIP PABX’s a few times with Patton boxes, but the docs were always for T1 not our E1.

I don’t really miss it, but it’s kinda cool in retrospect.

Man, can't disagree more. I didn't become aware of ISDN until I was using a 14.4k modem for a dialup internet connection, and the idea of having an always-on "digital" connection to the internet that was almost 10 times as fast as what I had was absolutely, unfathomably futuristic.

It seemed like the kind of thing they only had in Europe and Japan though. I was aware that some people in the US had it, but I had no idea how it was delivered or how one would go about getting it.

In the end, we were super late to getting DSL -- I think maybe 1999 or thereabouts, long after most neighborhoods near me had it. Going from 33.6k to 256kbps was the biggest "real" jump in internet speeds I've ever had, to this day.

By comparison, going to a shared LAN on a college campus, or a 10Mbps cable connection, to 25Mbps, to 100MBps, or whatever series of jumps got me to 250Mbps and beyond were barely noticeable from a user experience standpoint. Yes, files downloaded faster, but it didn't "feel" faster in normal interactive use.

Hell, I only got gigabit fiber "because I could" and the jump from 1 gig to 10 gig symmetric is almost laughable because it's impossible to use anywhere near that much speed on a day to day basis.