Written 1 August 2024

Dial-Up at Home

Back when the Internet was new in people's houses, you called it on the phone like a pizza delivery shop and, like some authentic Italian joints, it yelled back at you. With love.
SCREECHING INTERNET NOISES

I started collecting old palmtops/handheld PCs/ultra-light laptops/whatever devices because they're a cool form factor. They all had a couple things in common:
No ethernet port
No Wi-Fi
Built-in modem OR a PCMCIA slot

Dial-up was the common denominator. Where I live, in theory, I can get a real phone. But reality is that will cost a lot money for getting one device online at a near useless rate. Another reality is that the modern Internet isn't friendly for such devices.

End Goal

Every good project has milestones and end states. This is not one of those. The milestones occurred to me as I hit them because I don't know enough to figure out what a major accomplishment is before it makes sense. Learning!. In retrospect, here are the goals:

  1. Create a PBX that accepts SIP registrations from 2 phones
  2. Succesfully connect a phone call between 2 clients
  3. Add a modem to our "ISP" server and route traffic from it to the LAN/Internet
  4. Establish connection from client device to ISP modem
  5. Browse the Internet
  6. Create a dial pool and connect more than one device to our "ISP" at once
  7. *BONUS* Run a dial-in BBS, because that's cool as hell in a "I've never talked to a girl" kind of way



Technical Challenges

There are a number of technical challenges to this, chief of which is that protocols for communicating on the Internet have evolved while all of my palmtops are locked in a much simpler time. My earliest devices were lucky to even have a TCP/IP stack within Windows CE, so HTTPS is out of the question. This is a hurdle many others have to contend with and there are out of the box solutions that I'll cover later.


The next technical challenge: Interfacing a modem with my existing network. I already have a POTS phone on the network, but its connected through a GrandStream ATA and direct dials an IP and port. So, the next challenge was obtaining a modem that could talk the same language as my my devices with built in modems. This was relatively brief, USRobotics gear is all over eBay, including business class devices that used to be 4 figures of remote connectivity.


Modem to modem connections are imminently possible. In fact, you can do that with a a single, 2-port ATA by having it simply direct dial the other port. But that's not dorky enough, I'm here for the real deal of dialing through a PBX and getting transferred to another modem. Besides, buying a 2 port ATA for every device I want online will somehow be pricier than what my stated end goal will be.

Non-Issues

This will be brief, because there were very few things that will not be an issue. First, one friend of mine who is admittedly more radio oriented than computer expressed concerned that these devices would be unwillingly violated by the Internet as soon as they were online. Fair assumption, seeing as these devices are 20+ years old and don't even have a concept of virus protection. So why is this a non-issue? Easy. The Internet generally doesn't have a concept of the architectures on which these devices run. They are primarily SH3 CPUs, with a couple of ARM and MIPS devices. This is a target pool so small, niche, and not critical to any infrastructure that no credible threat would actually bother with it. I told my buddy that, should one of these devices get compromised, I'd immediately turn it over to a museum as an heirloom, then track down the perpetrator and buy them a beer.
And that's it. Everything else about this is a problem and not remotely worth your time.

Unless you're rad as hell like me.


Hardware

Ebay is one of the greatest ways to buy things you don't need at prices that let you think you're still fiscaly responsible. Let's look at all the silly gear I bought and the relevant specs:

USRobotics Courier Business Modem

This modem was a heavy hitter back in the day, built for always connectivity to the home office, as well as out of band control of assets.

General Specs

USRobotics 3453C Courier Business Modem

USRobotics 56k USB Controller Dial-Up Modem

This is a relatively unique piece of kit in the list because it's the only USB hardare modem I can find. This is important because while soft modems are fine for dialing-up, they're nearly impossible to get working as the dial-in modem. The combination of USB and hardware modem makes it uniquely suitable as an ISP modem under Linux. More on that later.

General Specs

USRobotics 5637 USB Modem

Software

And it's a hard