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What Was ISDN?

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Re: What Was ISDN?

#41

Post by a-dub »

ufocia wrote: post #31
a-dub wrote: post #23

Earlier quoted context omitted.

i guess you're right about 33.6kbps... point stands, if you wanted to go faster than analog modems in residential settings, before DSL and DOCSIS, ISDN was often the only game in town. BRI did not have free local calling with pacific bell at the time and "local long distance" or metered within NPA calling was quite expensive- often times a lot more expensive than actual long distance calling.

Sad to hear about the BRI billing from PacBell. 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 gene…

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

ahh yeah i forgot about that. the other side was direct digital and often ISDN PRI. ascend (or what was left after lucent bought them) made a device called the portmaster 3 that had a two port PRI and an ethernet port. it was an all in one 56k dialin modem bank, SLIP/PPP endpoint and router that would provide ~26 dialup lines with just a few cables.

i believe the way it worked was that it spoke digitally to the customers local C/O and then would do the DAC for the downstream channel with the shortest possible local loop allowing for more aggressive trades of reliability for bandwidth. it was all transparent to the customer though, they'd just buy a 56k modem and plug it into a POTS line.

cool stuff!

Re: What Was ISDN?

#43

Post by NetOpWibby »

poulsbohemian wrote: post #29

I remember visiting relatives in Switzerland in the 90s and it was the first time I’d seen ISDN - felt like they were living in the future while we were still on dialup in the US. I was thinking earlier today how when I was that age how amazing it would be to have fiber someday - has taken 25 years but I finally have it at home, and it still isn’t fast or reliable enough

The future we wish for is often subpar in reality. Thanks monopolies.

Re: What Was ISDN?

#44

Post by Sharlin »

jonathanlydall wrote: post #40

I had ISDN in South Africa for a while back in the day. Aside from the higher throughput, one of the other great things about it compared to analogue dial-up modems was the almost instant connection speed while old analogue took tens of seconds, maybe even a minute. But the biggest thing that really made it feel “responsive” was its digital nature, meaning that your baseline latency was mere sub-10 milliseconds inste…

Yep, that latency thing was a huge deal to Quake(World) players back in the day. ISDN really did give a big (some would say unfair) advantage over "dialup lamers", and gaming was probably one of the main reasons for investing (or maybe more commonly, begging your parents to invest) in ISDN.

Another advantage I don’t think the article mentioned was, of course, the ability for others in the household to use the regular phone while you were online, removing a common source of intra-family conflicts. In the end, though, consumer ISDN remained a transitionary technology and most people skipped straight to DSL or cable.

Re: What Was ISDN?

#45

Post by mzi »

For me it was the feeling of "being on the internet" that made ISDN so special. My computer had a fixed IP address, a name in DNS and the router at work had of course dial-out, so I could telnet into it from anywhere on the planet, authenticated with the same Kerberos tickets that got me in at work.

Re: What Was ISDN?

#46

Post by koobe »

Before ADSL was available and affordable, I did have ISDN at my place. It was charged by the minute, so I could not leave the data always on. I set up an always on Linux box at my apartment with a PCI ISDN adapter. A voice mail application answered calls on one of the 4 ISDN phone numbers.

I modified this voice mail application to accept a PIN code to open PPP on the other B-channel to the ISP and read back the dynamic assigned IP on the phone. This was something I could not do with a single analog phone line and a modem.

This was not the reason to get the ISDN, but this was the first time I could remotely access my systems at home at will. Not that I needed to that much, but I could.

Re: What Was ISDN?

#47

Post by sllabres »

Back then we had four primary rate connections 2.048MBit/s each (30 ISDN B channel) to transmit data to several subsidiaries. This was quite a lot of bandwidth at the time. Our litte on demand network started at 02:00 in the night when tariff was lower (paid by connection time, not by volume :D) and used Ascend and Cisco routers Ascend was always much quicker setting up MPPP channel and therefor preferred, but Ciscos where a bit better utilizing larger 30 channel MPPP connections (and some destinations preferred Cisco)

It was quite 'fun', because starting with morning when tariff changed everything had to be transmitted and if something didn't work out right (to slow buildup of the MPPP channel, delay in the batch jobs delivering the data) someone had to monitor the process in the next night to prevent further backlog. For a long time there was only a 64kBit (later 128kBit) connection over the day regular connectivity.

Eight MBit carefully distributed over 120 channel. With all the support equipment a server rack, filled by 2/3. Ridiculously little today, even over air. It sounds as if one talks about the ancient Egyptians, but it is only 25 ago

Re: What Was ISDN?

#48

Post by forgotusername6 »

I have quite fond memories of working on ISDN video conferencing in the not so distant past. Video calls are quite possible on 64kbps (qcif, g728 and h264). Though it was also possible to use a whole PRI and make a call using 2Mbps.

Re: What Was ISDN?

#49

Post by aspenmayer »

65a wrote: post #30
usr1106 wrote: post #9

Earlier quoted context omitted.

20V? Germany has traditionally used 60V. The current spec allows 20V - 105V https://www.nostalgietelefon.de/beachten/1TR110-1%20Ausgabe%...

Ma Bell used -48v DC in the US, which was backed by a giant lead acid battery at the local exchange. It was quite common to have ADSL circuits working during major power outages, so long as the modem and servers were on redundant power. It might still be worth coming up with a USB charger circuit, but I assume current draw is metered.

I’ve seen COTS adapters which connect to a standard phone jack with pass through and provide one USB port, advertised as an emergency/backup power. I don’t know how much power they can draw, however.

The one I’m familiar with is called:

VR3 (brand) Phone Jack Powered Emergency Night Light & Charger (model: PJNL-USB)

Re: What Was ISDN?

#50

Post by midasuni »

Still use it, and there isn’t really a replacement at the price point or reliability. When all you need is a single voice circuit for a radio station to be able to contribute from the middle of nowhere, it fits the bill very well.

Obviously it’s going (how soon? Well we will see shortly if 2025 is kept to), and it will be a sad day. International isdn is pretty much dead, and has been for some years, but in the U.K. it is still reliable and functional.

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