Serbia (former Yugoslavia) was mostly in turmoil in the 90s, and while I did get online using dial-up in 1995, new tech was (very) slow to arrive: I used ISDN for a few short years in early 2000s before ADSL finally arrived. It was amazingly reliable even in Serbia.
But compared to the regular 20V phone line, ISDN used something like 120V (which I learned by carelessly changing the connector like I used to on the regular phones), and in a country where power went out regularly, I wondered how much power could I get out of it for emergency situations.
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)
ISDN was a great upgrade for me in the 1990s, and once I found out how to couple two lines into one "massive" 128k, it was pretty mind blowing. Connecting to the Internet was also snappy (as opposed to dialup with the whole modem song) and could even be done on demand if you were brave.
Well, it wasn't actually 128k. Technical reasons limited it to 112k. That's why 56k instead of 64k modems. There was the Shotgun Modem which required 2 separate phone lines, but would bind them together. I never bothered reading up on how binding 2 PPP connections worked, but I guess it worked well enough that it was a legit product being sold. I went from 28.8k to ISDN, so I skipped the 56k altogether.
Of course, ISDN and 2 56K connections are only similar in bitrate and are not the same thing at all.
You're right the BRI was actually 144k, 2x64k B channels and 1x16k D channel. 112k was available on misconfigured hardware and gimped bit-robbing lines where some of the bits on the B channels were used for signaling in lieu of a D channel.
Yeah I think the binding of the lines was much easier with ISDN as one never went through the analog level (except if you want to be really pedantic). It was digital from the ISDN adapter. No ringtone etc.
> Well, it wasn't actually 128k. Technical reasons limited it to 112k. That's why 56k instead of 64k modems.
That’s not fundamentally true about ISDN - in North America, at least, most basic rate connections and every single PRI I ever encountered had eight-bit-clean channels and were true 64kbps.
With modems (I assume you mean analog modems,) that was only part of the reason. There were others that would have been far more difficult to solve in practice, and there was largely no point in doiny so as xDSL technologies came around at roughly the same time.
Multilink PPP worked quite well, even beyond bonding two channels.
I had ISDN back in 1996 and it was great. It felt dramatically faster than a 56k modem because ISDN has much lower latency. Web pages were so simple in those days they loaded almost instantly.
I remember that back in the xDSL days we had never-ending discussions about interleaving vs fast-path. If you could enable fast-path, you could reduce your latency in half, but not all ISP supported it and your connection would be more sensitive to noise and errors, so it was not always worth it.
Upstream mattered a lot for responsiveness. This was really before the idea of ACK Prioritization [1] TCP connections, so the standard small upstream of 56K had an impact that didn't quite get felt as much as it did on symmetric ISDN.
Most things silently incorporate ACK prioritization now, which makes the typical asymmetric internet connection like a cable modem work better. But before then, it was a problem... And those of us who hand-solved it on DIY firewalls really reaped the rewards.
Extremely affordable in my area at the time, due to massive subsidies from the former government telco, to push it to the masses.
Also the only solution from private telcos at around the same time, where said former gov telco simply wouldn't offer early DSL at all, while private upstart offered ISDN whith dynamic channel bundling at flat rated 29,99 per month, so 128Kbs! Yay!
Since it was pushed so hard by subsidies, many had it, the equipment was cheap, and the sound quality that came with it was rather good. Often still unmatched by some crap which people accept as 'normal' nowadays.
This was my experience too. I was looking for something better than the 56k modem, but ISDN was 10 times as expensive and like 20% faster.
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.
Fwiw open access fiber systems have that now. In Utah you can actually subscribe to multiple ISPs over Utopia fiber, and it's mostly just an issue of configuring your terminal to talk to them.
Since it's a 100% eithernet network, any off the shelf device with an SFP cage can connect to it
That would be nice. My local fiber option is Verizon or nothing. Verizon's tech works very well, but their customer service is terrible. Many people think that Verizon only pushed FiOS as hard as they did because it gave them a way to push out the competitors they had on DSL. Once DSL died off so did their drive to deploy FiOS.
Frame Relay was horrible, and the bane of our existence at the ISP.
We had a wide variety of customer connections, from dialup to an honest-to-God 14.4Kbps digital leased line, to 56K and T-1 leased lines and some T-3s in our backbone.
Our manager was a huge proponent of SMDS; in fact the SMDS diagrams made liberal use of the "cloud" icon to depict connections going in and out of the telco's switched network. He was able to derive great reliability and value from SMDS connections, and they were probably our fastest links available.
By contrast, Frame Relay was some sort of a hack to avoid having a "real" 56K line run to a customer, and they went down all the time. They were so unreliable, we could hardly stand it. The FR customers became quite disgruntled.
This was in the mid-90s. I don't know if FR improved after that time or got a better reputation elsewhere. But we would definitely rather not have it around.
FR was problematic because the FR networks were oversubscribed, which was actually one of the benefits of the technology. The tech support for FR was also lackluster at best. The nice thing about FR was that you could aggregate multiple connections on one piece of equipment and pay based on usage rather than committed bandwidth.
The over-subscription was definitely a problem. The ISP I worked for had a fractional T1 in their main POP for frame relay (512K or something?) There was about 4 to 5x in bandwidth needed for customer connections, assuming 100% utilization. During peak times in the evening, the FR was massively overloaded and ping times would get into the 100's of milliseconds (normally it was 10 to 15ms IIRC.) The connection never went down though, even when they were slow.
I had 56k FR at home in the 90’s. I worked for an ISP and it was a perk offered to some employees. The connection never went down once in 4+ years. The reliability must have depended on your LEC.
dual challenge ISDN was a reason I was trying to move into a Roseville Telephone (Northern California) area. at the time, it was awesome. web pages were like flipping pages in a book. the latency was nice and low for the time.
Man, the idea that ISDN was going to last 50 years has to be one of the bleakest Bellhead memes I think I've ever heard. "You will only have 144kbps and be happy."
It's a service framework for subscriber based circuit switched connections. The modulation format is separate and I doubt they expected to keep such a meager encoding for the long predicted life of the network.
The error was in not seeing packed switched networks as the clear winner not in choosing a modulation scheme that was designed to bring maximum bandwidth over existing copper infrastructure.
In any case, the strength was that you could bond up to 24 channels in a North American PRI package, which is what a lot of businesses considered their "T1" service, or used as a mixed group of DID and LOOP channels for calling.
Interestingly, in the end, they used bonded ADSL to provide an encapsulated 24 port PRI "circuit" to the customer using just 4 wires.
Actually, it was envisioned that you'd use the D channel for packet switched data traffic (not IP, more like X.25). Why would a private person use more than 16 kbit/s for a home computer? Much more important to have two high-quality voice lines! And we are busily working on ATM-based Broadband-ISDN to even make high quality video calls and TV available! Just you wait!
in the mid-90s it was often the only option for >14.4kbps internet in residential areas. unfortunately the tariffs charged by the minute for voice and data calls so it was prohibitively expensive (at least for our household).
the hack (in the US) was that ISDN was often offered as part of "centrex" service which was a sort of phone company managed PBX-as-a-service offering. so rather than businesses setting up their own local mini telephone switch (a PBX) that they'd hang all their extension phones off of, they'd just get ISDN phones and connect directly to the phone company and have the phone company manage it all. the trick was that "intercom" calls within a centrex were unmetered (think intra-office calling), so an approach to building an ISP would have been to sign up for centrex service and then install a branch phone on that centrex at each customer site, then all calls into the ISP would be intercom calls and would be subject to unmetered tariff.
i used to drool over the idea of one day getting my hands on an ascend pipeline 50 and its sweet, sweet 128kbps of bandwidth. then one day i finagled a visit to a local software company and met the founder who was struggling with getting one working (it was paired with one in his home, so he could make use of the company's t1). he jokingly offered that if i could get it working he'd offer me a job: 45 minutes later the link was up and few hours after that i was shaking hands with the head of engineering as they made good on the founder's word. fun times!
Interesting. v.34 ratified in 1994 supported 33.6 kbit/s. In at least some areas POTS calls to local prefixes were unmetered. ISDN BRI had similar, if not identical, tariff.
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.
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.
> 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.
On the ISP side, ISDN was a crucial part of scaling out dial-up ISPs. CLECs (Bay Baby Bells) would route calls from geographically large calling areas --- all of Chicago, say --- to a single colo cage on an ISDN PRI. Access concentrators (then called "terminal servers" --- Portmasters, Ascend routers, Cisco AS5x00s) would take 56k modem calls on individual PRI channels.
minor point, the Baby Bells were incumbents in the market and were referred to as ILECs. they were mandated to lease their infrastructure to CLECs at reasonable rates to allow for competition.
incidentally, there were many terminal servers that didn't require authentication, or would accept default credentials. this was a common way to get free internet access back in the day!
Incidentally, The Serial Port on YouTube (no affiliation) is doing an excellent series on old-school ISPs, getting hands-on with the equipment to set up their own ISP.
I used ISDN internet for a few years in the 90s before DSL became available. It was a big improvement over normal dial-up because you could still use the phone while online. Or use two lines for 128kb downloads if you weren't expecting a phone call.
Got ISDN as a previous job as parttime helpdesk employee at an ISP. Together with the rise of numberous dail-up providers, including the legendary Superweb. It would allow free internet against a fix rate, not paying per minute, which was something new for the Netherlands. It would only allow one or two hours after it would disconnect you and you had to redial. Due their succes getting dialed in again could take quite long (too many users, not enough lines). So I wrote code/script and made changes to the Linux distribution to allow me to dial with my second line as part of my ISDN, starting ten minutes before I would get disconnected, and “transfer” the connection to the new connection when it was finally able to dial-in, hence having internet 24hours a day. Good times! Superweb didn’t exist very long…
it was shell-scripting (bash). And i'm not sure, but it i think i was mandrake linux distro. It was quite the work to get ISDN working properly, especially to use two lines at a time (one dialing, while the other one was in use).
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
ISDN was widely available in the US (it ran on the same copper pairs you already had) but was never all that popular. You could essentially _always_ get it deployed and it was the base-level connectivity back in the 90s for remote sites. I had it installed in a few crappy apartments much to the confusion of the local installers, the line price wasn't crazy expensive but finding a local ISP that would agree to reasonable always-on pricing was more challenging.
Then we had two very different lived experiences - my parents couldn’t get it in the Seattle area, I couldn’t get it where I was going to college in the midwest, and what I recall was that it was very expensive, like double the cost or more, or any available dial-up option.
In the Southeast, you could get it but it took some more or less annoying negotiating with Bellsouth bureaucracy, usually had install issues because the residential installers didn't do it that often, and it was way more than double the cost of dialup. There were plenty of ISPs.
This was similar to my experience in SE Michigan & NW Ohio in the late '90s to early '00s. Ameritech required you to order 2 ISDN phone lines, which cost somewhere around $80 per month, each. ISPs charged extra for the ISDN services, too.
I remember connecting my laptop to ISDN public phones in Tokyo in the early 2000s to check my email when I was away from my office. Not a particularly fond memory, but it gave me an early taste of the always-connected world we live in now.
The phones apparently still exist [1] but the digital data function is being phased out [2].
My main exposure to ISDN in Australia was in radio stations.
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.
ISDN did have multiple channels, in Germany you would get two data channels (B1 and B2-channel, 64 kB/s), and the line has a D-channel (something like 4kB/s) for network purposes. First you could bundle the B-channels to get twice the speed, at twice the price and the land line was busy if one did that. That feature got me into trouble with my parents quite regularly.
Second someone figured out that the D-channel can also be used to send data to arbitrary endpoints in the phone networks and dropped a messenger app on a Friday afternoon in '98 or thereabout. That was a pretty fun weekend, unfortunately the hack had stopped working when I came back from school on Monday.
Same here in the Netherlands, somewhere between 1998-1999 using KPN Telecom. I was in high school and convinced my parents to upgrade from single-line PSTN to dual-line ISDN, so we could call and surf the internet at the same time. At the start of 1999, because of the rapid increase in phone and internet traffic, the national call tariffs had been reduced a lot[1]. Tariffs were even cheaper in the afternoon and during the weekend.
For normal internet browsing the single ISDN connection (64 kbps) was enough. Then later in 1999, Napster[2] launched and I was hooked! This made me use bundling ISDN channels quite a lot. Because of the cheaper tariffs, weekends where great because I enabled the bundling around midnight until early in the morning, so my parents wouldn't notice. :-)
I was on ISDN until 2002, when ADSL was available here and we could be online 24/7 for a fixed price. I do remember my ISP (XS4ALL) still had a fair-use-policy for downloading, which they removed a few years later.
Oh yes, the D channel, holy grail of always-on dreams. Young me spent countless hours staring at AVM header files dreaming of finding an angle that would enable me to sneak free bytes to a friend who also had ISDN.
When we first got Internet at home (also Germany), it was ISDN, but only single channel. So being connected meant not being reachable by phone. That meant my mom strictly limited our Internet access to 1-2 hours a day. I was so glad when we finally got that second channel :D
I did my training at Deutsche Telekom, and our instructors told us a story of an ISP that tried to sell a flatrate working over the D-channel; apparently they had some reliability issues and did not last long. That must have been in 2003 or early 2004, by then of course DSL had arrived and rendered such experiments (and ISDN in general) more or less pointless.
| The problem with ISDN was simple: We already had effective options for everything it was trying to do
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.
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 instead of 150ms for analogue.
Generally our monopoly telco was despised, but they had a great offer called “R7 weekend” where from 7PM Friday to 7AM Monday, no matter how long the (domestic, possibly local, only of course) call you would never be charged more than R7 for it. This meant that you could be connected for the whole weekend at 128kbps for R14 (~1.4 USD) at the time (2003-ish).
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.
We used to play Quakeworld and later Team Fortress after hours at our office. A networking consultancy. Where we went through dedicated T1s, multimegabit SMDS on to metro ethernet. We were the LPBs and got accused of cheating constantly, which was kinda true.
Do you know if Telkom offered ISDN around ‘95 thru to ‘01?
My parents had “two lines” back then so we could always have access to the Internet, even while talking on the phone. I recall, vaguely, using dial up but we may have had an ISDN line. In part, because my Dad wanted to order LaserDiscs from the US while my Mom was chatting away to family.
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.
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.
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
I thought primary rate interfaces were 24 channels (23 bearer channels plus one data channel) for a total throughput rate of 1.5 Mb/s, but apparently that’s only the case in the US, Canada, and Japan. European PRIs (E1 vs T1) are as you described. TIL.
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.
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.
163 comments
[ 2.8 ms ] story [ 213 ms ] threadBut compared to the regular 20V phone line, ISDN used something like 120V (which I learned by carelessly changing the connector like I used to on the regular phones), and in a country where power went out regularly, I wondered how much power could I get out of it for emergency situations.
https://www.nostalgietelefon.de/beachten/1TR110-1%20Ausgabe%...
The one I’m familiar with is called:
VR3 (brand) Phone Jack Powered Emergency Night Light & Charger (model: PJNL-USB)
Of course, ISDN and 2 56K connections are only similar in bitrate and are not the same thing at all.
That’s not fundamentally true about ISDN - in North America, at least, most basic rate connections and every single PRI I ever encountered had eight-bit-clean channels and were true 64kbps.
With modems (I assume you mean analog modems,) that was only part of the reason. There were others that would have been far more difficult to solve in practice, and there was largely no point in doiny so as xDSL technologies came around at roughly the same time.
Multilink PPP worked quite well, even beyond bonding two channels.
Most things silently incorporate ACK prioritization now, which makes the typical asymmetric internet connection like a cable modem work better. But before then, it was a problem... And those of us who hand-solved it on DIY firewalls really reaped the rewards.
[1] http://www.benzedrine.ch/ackpri.html
Also the only solution from private telcos at around the same time, where said former gov telco simply wouldn't offer early DSL at all, while private upstart offered ISDN whith dynamic channel bundling at flat rated 29,99 per month, so 128Kbs! Yay!
Since it was pushed so hard by subsidies, many had it, the equipment was cheap, and the sound quality that came with it was rather good. Often still unmatched by some crap which people accept as 'normal' nowadays.
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.
Since it's a 100% eithernet network, any off the shelf device with an SFP cage can connect to it
We had a wide variety of customer connections, from dialup to an honest-to-God 14.4Kbps digital leased line, to 56K and T-1 leased lines and some T-3s in our backbone.
Our manager was a huge proponent of SMDS; in fact the SMDS diagrams made liberal use of the "cloud" icon to depict connections going in and out of the telco's switched network. He was able to derive great reliability and value from SMDS connections, and they were probably our fastest links available.
By contrast, Frame Relay was some sort of a hack to avoid having a "real" 56K line run to a customer, and they went down all the time. They were so unreliable, we could hardly stand it. The FR customers became quite disgruntled.
This was in the mid-90s. I don't know if FR improved after that time or got a better reputation elsewhere. But we would definitely rather not have it around.
until cable & DSL came along, it was awesome.
The error was in not seeing packed switched networks as the clear winner not in choosing a modulation scheme that was designed to bring maximum bandwidth over existing copper infrastructure.
In any case, the strength was that you could bond up to 24 channels in a North American PRI package, which is what a lot of businesses considered their "T1" service, or used as a mixed group of DID and LOOP channels for calling.
Interestingly, in the end, they used bonded ADSL to provide an encapsulated 24 port PRI "circuit" to the customer using just 4 wires.
the hack (in the US) was that ISDN was often offered as part of "centrex" service which was a sort of phone company managed PBX-as-a-service offering. so rather than businesses setting up their own local mini telephone switch (a PBX) that they'd hang all their extension phones off of, they'd just get ISDN phones and connect directly to the phone company and have the phone company manage it all. the trick was that "intercom" calls within a centrex were unmetered (think intra-office calling), so an approach to building an ISP would have been to sign up for centrex service and then install a branch phone on that centrex at each customer site, then all calls into the ISP would be intercom calls and would be subject to unmetered tariff.
i used to drool over the idea of one day getting my hands on an ascend pipeline 50 and its sweet, sweet 128kbps of bandwidth. then one day i finagled a visit to a local software company and met the founder who was struggling with getting one working (it was paired with one in his home, so he could make use of the company's t1). he jokingly offered that if i could get it working he'd offer me a job: 45 minutes later the link was up and few hours after that i was shaking hands with the head of engineering as they made good on the founder's word. fun times!
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.
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.
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!
incidentally, there were many terminal servers that didn't require authentication, or would accept default credentials. this was a common way to get free internet access back in the day!
Playlist: https://youtube.com/playlist?list=PL7qsY2QIYd8PLW1zXVcNFVA_o...
The phones apparently still exist [1] but the digital data function is being phased out [2].
[1] https://www.ntt-east.co.jp/en/ptd/contents/mag_public_digita...
[2] https://www.ntt-east.co.jp/ptd/contents/mag_public_digital.h...
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.
Second someone figured out that the D-channel can also be used to send data to arbitrary endpoints in the phone networks and dropped a messenger app on a Friday afternoon in '98 or thereabout. That was a pretty fun weekend, unfortunately the hack had stopped working when I came back from school on Monday.
For normal internet browsing the single ISDN connection (64 kbps) was enough. Then later in 1999, Napster[2] launched and I was hooked! This made me use bundling ISDN channels quite a lot. Because of the cheaper tariffs, weekends where great because I enabled the bundling around midnight until early in the morning, so my parents wouldn't notice. :-)
I was on ISDN until 2002, when ADSL was available here and we could be online 24/7 for a fixed price. I do remember my ISP (XS4ALL) still had a fair-use-policy for downloading, which they removed a few years later.
[1] https://www.acm.nl/en/publications/publication/9213/OPTA-agr...
[2] https://en.wikipedia.org/wiki/Napster
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.
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 instead of 150ms for analogue.
Generally our monopoly telco was despised, but they had a great offer called “R7 weekend” where from 7PM Friday to 7AM Monday, no matter how long the (domestic, possibly local, only of course) call you would never be charged more than R7 for it. This meant that you could be connected for the whole weekend at 128kbps for R14 (~1.4 USD) at the time (2003-ish).
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.
Do you know if Telkom offered ISDN around ‘95 thru to ‘01?
My parents had “two lines” back then so we could always have access to the Internet, even while talking on the phone. I recall, vaguely, using dial up but we may have had an ISDN line. In part, because my Dad wanted to order LaserDiscs from the US while my Mom was chatting away to family.
Seems possible, but a second regular phone line seems just as possible.
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.
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
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.