I have caught a bug to play with ISDN

Categories: ISDN

I have caught a bug to play with ISDN.

The closest I have ever gotten to ISDN was at a job I had at a newspaper circa 1995. They were hosting their website on-premises via ISDN. It felt magical.

At the time, web development interested me more than infrastructure. I marveled at how ISDN worked and relished the blazing speeds, but otherwise carried on tinkering with HTML in BBEdit. I assumed I would have plenty of time to learn more about something as futuristic as ISDN as my career progressed.

The world forgot about it shortly thereafter. Myself included.

I am not sure what has sparked my interest in it now. An article recently on Hacker News may have had something to do with it. The telephone network genuinely fascinates me, which helps. Interesting, well-designed, or at least well-intended technologies that fail spectacularly in the market have always had a place in my heart; ISDN might qualify.

In any case, I am now exploring ISDN, how it worked, and how people used it. I have discovered a surprising and delightful challenge: much of the activity around ISDN pre-dates the Internet. Few web sites, current or in the Internet Archive, offer much about it. If any forum sites or mailing lists discussed it, they appear to be long gone. I suspect this project will take me to the library for printed materials. An O’Reilly book? Que? Sams?

I have hope, though. ChatGPT offered enough general information to help me figure out useful search terms. I found a vein of old ISDN equipment on eBay, which constitutes an unexpectedly useful resource in its own right. Retro enthusiasts have popped up on Reddit with pointers. Someone published a Ph.D. thesis on ISDN that helped with terminology. I feel confident I can find what I need. Even now, I have found enough to start collecting equipment, and I think I will be able soon to set up a small ISDN lab at home.

For my first goal, I aim to get two ISDN devices placing and receiving calls to each other. I have ordered two old Adtran ATLAS access devices, one of which is bound to work. I have ordered two Ascend Pipeline routers and one Netgate router, all in unknown condition, but at least two of which I hope work.

For more ambitious goals, I have a few ideas:

  • Replicate the setup at my newspaper job in high school
  • Set up a 56K v.90/v.92 modem pool
  • With FXS ports, light up my son’s collection of old phones
  • Something “on the real internet” yet to be determined

My first batch of equipment begins arriving this Saturday. Until then, I have more searching and reading to do.