ISDN: The Untravelled Path of Mobile Computing (2015) | Hacker News Reader

ISDN: The Untravelled Path of Mobile Computing (2015)

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29 pointstodsacerdoti33 comments

I recall my dad getting bonded ISDN at his shop years ago (1996/7?) the jump from 28.8kbit (x2 56 was just out but only supported on some ISPs iirc) to 128kbit seemed like another world. So much so I'd lug my own PC down and pretty much spend all my Saturdays there. Good times

I got very lucky about then when my father got his work to pay for bonded ISDN to our house in the middle of nowhere. Being able to connect to BBSes at 128kbit was insane.

But the big thing with ISDN and the internet was the latency. A bunch of mudding friends brought over their computers all the time since they could suddenly play with a latency almost as good as the older kids who played from their university dorms.

128 kbps ISDN had just about 40 ms latency. A significant improvement to a modem, which had about 100 ms+ IIRC, often a lot more, even 500 ms+.

That low latency made ISDN feel fast, sometimes even better than the first ADSL 512-1024 kbps modems that used interleave error correction method. Interleaving caused latency to be about 60-70 ms IIRC, making the higher bandwidth ADSL connection feel slower.

Of course then there was 144 kbps IDSL, which was really 2x 64 kbps ISDN + 16 kbps ISDN control channel.

I remember my ISDN having closer to zero latency. It was kind of amazing watching Web pages jump onto the screen.

It feels like you're adding about 30-50ms onto the base latencoes here. Are you/were you fairly far from any major internet exchanges when ISDN and ADSL arrived?

IIRC, those were ping latencies to the first hop discovered by using traceroute.

ADSL was about 30-35 ms with fast path in use instead of interleave.

My experience with fast path ADSL was about 8 ms. I don't think I was on interleaved ADSL, but interleaved VDSL2 is about 20ms.

Was this in year 2000 or so?

I had ADSL1 at 6m/768k fast mode roughly 8ms latency from 2004-201x; the latency was pretty much constant (it did get slightly better when I replaced my modem after the first one died, but the improvement was less than a ms, but measurable). ADSL1 didn't change much after release afaik, changes came through ADSL2 and VDSL and such. The scourge that is PPP over Ethernet did become more popular later in the life of DSL though.

IDSL was the first "high speed" connection I ever had at home. What a dream it was compared to dialup! Always on and 3-4x faster than the best dialup connection could do.

The 2 x 64kbit was nice and all, but being able to surf all evening (reduced tariff) on 1 line and have the house phone available for incoming calls (for my parents) at the same time, that was the game changer for me. No more, "just 30 minutes internet tonight kids, I'm expecting an important call", just dial in at 8 and start the download manager for the entire evening.

I wonder, were there any countries where ISDN BRI became a "default" service, i.e. where it was normal for it to be installed in every household to the same extent POTS was?

ISDN was pretty prevalent in Germany, but it always would cost a premium compared to POTS

Not really true from the times I remember, because heavily subsidised.

I don't remember the base price, but I'm pretty sure for Telekom there was like a 5-10 DM premium for ISDN over analog, at least in 98-2000

One thing that still confuses me about ISDN is that despite most of it being standardized in a series of ITU specifications, I see a lot of phones and other TE's advertise support for vendor specific protocols and other standards (National ISDN protocols, special 5ESS protocols and later things like DSS1)

What I don't get is the signalling is all standardized (LAPD, X.25 or maybe Frame Relay at layer 2, and Q.931 at layer 3) and the actual data should just transparent to the protocol and only relevant to the devie function (I imagine a typical voice call would just alaw or ulaw data). So unless there's something going in the upper layers of an established call, why the need for various proprietary protocols that from the sounds of it are incompatible.

There are devices and tools to simulate this proprietary protocols, so I suppose in theory I could reverse them, but they’re either rare to come by or very expensive for a random hobbyist such as myself.

ISDN was used a lot in Germany and was disabled just a few years ago. I still remember the agony of getting my Linux PC to work with the Fritz!Card (on the ISA bus) to finally be able to be online for 3 cents a minute on the Internet. ISDN was really fast and extremely stable though.

Hehehe. Wrong move :-) Should have used something with either a chip from Cologne Chip Design, or the other big asian player whose name I can't remember at the moment. Anyways, both were way more affordable and had stable drivers. Basically looking at what Isdn4Linux, and later HISAX supported well.

or maybe just a little too early. I used several PCI Fritz! cards back then on Windows and Linux and they worked flawlessly, for years.

I seem to recall in the US, there was a narrow window of time where ISDN was interesting - one of my parents had an ISDN connection to their office installed in our house. Within a couple years, the vastly faster ADSL became available followed shortly thereafter by cable internet.

IIRC, in California, ISDN only had a per minute tarrif (which would run at 2x if you used both B channels) and you usually had to pay your ISP more too, although I heard after 56k modems were widely deployed, you could use one B channel and usually get a 64k (both ways) connection for regular dialup cost.

In Sweden, ISDN was the default for anyone who wanted 2 phone lines (i.e. anyone who was self-employed and needed a business phone line)

Heh, I’ve been doing a lot of reading on ISDN lately, working on a user mode ISDN stack myself. Much more than I should tbh. I wonder if the ones pictured in the article use BRI or PRI interfaces, I’d have to guess PRI personally.

I actually have a phone like that on my eBay watchlist, except it’s a video phone (using H.320 I imagine) I’ve been meaning to pick it up, I’ve have a couple unexpected expenses recently.

PRI was similar to a T1. I kinda doubt they had that at the payphone level.

Perhaps you’re right. I was thinking that if this was part of a network of pay phones that they would want to be able to handle more than just the 2 calls per line an BRI would allow with less infrastructure (though I think lower rate calls are possible through additional multiplexing)

I'd guess it used BRI. PRI would probably have been considered too expensive to justify running to a payphone. My guess is the BRI socket on that payphone is only operable when you're not making a call, so the 2x64k BRI line can be assigned to the phone or passed through to that socket.

You're working on a user-mode ISDN stack - this sounds extremely interesting! Care to drop me a line? https://www.devever.net/~hl/contact

In the European country where I live, the telecom monopolist used ISDN as a necessary stage before ADSL. This was done to siphon off money from consumers for qt least 4 years before ADSL was offered, even though the tech was ready and in use in other countries such as Netherlands. This held us back in terms of development and innovation. I will never forgive them.

Are you talking about Poland? :)

National Telecom deployed Ericsson HiS (https://pl.wikipedia.org/wiki/Home_internet_Solution), a proprietary twist on ISDN (max 115kb/s, cheap to manufacture external USB dongle), between 1999 and 2004. Signup was about one full entry level local salary, then 1/6 monthly bill. I didnt hesitate one second, my monthly dialup bills were already approaching ~1/4 of what I was making.

At the time there were no alternatives other than local neighbor coop networks sharing >$1K monthly bills for T1 line.

Before we got ADSL we had ISDN when our local carrier introduced unlimited weekend calling only billing for the first minute as long as you never dropped the call.

I used channel bonding so I could get 128K using a Linux server as the dialer/proxy as the Windows drivers for the ISDN card was just too darn flaky.

Good times.

I had a bonded ISDN setup with my company paying half of the fees, back in 1997 or so. I got to work from home, over a rock-steady 128kbit connection, on my home Linux PC connected to my HP workstation in the office. It was a magical time.

Does anyone know how to perform a virtualized ISDN Network? Such as an emulation?

It would be so cool to get old ISDN phones working again. Quality is good, sound quality excellent and so on.

Fun fact: H.323, the VoIP protocol, is pretty much just ISDN (specifically, its signalling protocol, Q.931) over IP.

ISDN PRI runs over T1/E1, so I would imagine any T1/E1 PCIe card would do, if you can find the right software for it. Some Cisco routers, including old ones, accept modules with ISDN BRI ports, though I believe these are for connection to a service provider rather than a phone. Cisco IOS has VoIP functionality (if the right licences are enabled) and it can also speak ISDN over a Cisco E1/T1 module. There's also old PBX equipment you can find secondhand which speaks ISDN; for example, someone I know has a Cisco 2951 connected via T1/ISDN PRI to an old Meridian PBX, both purchased secondhand. It even has Cisco IP deskphones attached to the Cisco router which can call through to Meridian deskphones attached to the Meridian.

I'm not personally familiar with any of this, though if you contact me I can put you in touch with some ISDN hobbyists who are. https://www.devever.net/~hl/contact

Onyl possible in Japan. Because less vandalism (regarding the example public payphone pictured there, whith RJ-11 and RJ-45 sockets)

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