Dusting off the old analog dial-up modems

[fjellebasse]

Hi there,

I've followed this guide to create my own dial-up server: Dial-Up Server
Currently I have the following analog modems:
- TRON DF 56K (EXT)
- US Robotics 56K Sportster Faxmodem (EXT) - I just bought this New-in-Box
- LASAT Safire 56K (EXT)

I also just purchased a US Robotics 56K Courier V.Everything that is currently underway to my location.

The machines I use for the purpose of playing around with old dial-up connectivity is currently a Power Macintosh Beige G3 and an IBM Thinkpad T42.

I'm looking to find other people who enjoy using old modems for various retro stuff like BBS, IRC, WWW (Frogfind, theoldnet.com etc.) and so on.
It would be nice to get to know some ways to fine tune the setup, exchange tips and tricks, or find other use cases for old-school dial-up.

Anyone in here play around with this kind of stuff? What kind of modems do you have? What do you do with them?

PS. I was unsure of in which category I should put this post.

 

[Chuck(G)]

I've used telephone modems since the old Bell 103. I'm delighted that they've gone away and have given away all of my USR modems. Glad that they're not part of my life.

 

[fjellebasse]

I can see why one would feel that way. After all, it was a relatively slow procedure with the dial-up connection.
But it was also an exciting new time for me and I have a lot of good memories. Nostalgia at its finest
The US Robotics I just bought actually performs the worst in my setup so I packed it away again. I hope the Courier modem performs better.

 

[Chuck(G)]

The Courier Dual-standard, V.92 and V.Everything modems were top-of-the-line and used by BBS sysops extensively. I had them all. The Sportsters were junk.

Old line modems (pre-PC), such as Racal Vadic, Novation, Anderson-Jacobsen, Milgo, etc. were engineering masterpeices. The Telebit Trailblazer modems are particularly noteworthy.

Commercial computer-computer hookups were usually synchronous (bisync, HDLC, SDLC, etc.) using block-oriented protocols. No start or stop bits--just sync and data. Bell 208s were very common.

There's a lot to voice-grade modems that many people are unaware of. I don't miss them, my VDSL2+ modem is light-years apart.

 

[mark0x01]

Down this end of the world, finding a copper line to put one on is getting harder.
I still have an analog phone line in the house, but only as far as the ATA and then via the router to fibre.
In my experience, analog modem over ip doesn't usually fair too well, especially at the higher speeds.

 

[Plasma]

If you just want to screw around with modems, you can connect a couple together with a ringdown box.

 

[stepleton]

As a fun project for another life, it seems like it would be possible for the dedicated enthusiast to make "the other end of the line" by means of modern hardware. Since software-defined radio exists (and likely requires more challenging modulation than would be required here), I would suppose the capability to pursue this goal rather thoroughly is in reach, though I haven't investigated the potential in any serious way.

At first it's basically a homebrew combination of a phone line simulator (still surprisingly expensive on eBay --- anyone in the UK with a spare, please feel free to DM!) and a homemade modem. It's a gentle start though as you begin with V.21/Bell 103 at 300 bps --- you'd probably be able to accomplish this modulation with very little effort. Next it's V.23 at double and then four times the data rate, then onward, eventually getting to V.32bis and 14.4k, then the various V.34s to go up to 33.6kbit/s bidirectional.

By now things have been pretty serious for a while, but you're not going to stop there. V.90 is the real goal --- you're only going to get the 56k down that all four of your modems crave if your homebrew project has the soul of a late '90s digital phone network. The best you'll be able to do if you rig your Sportster to talk to your Courier is 33.6, and how could that ever be enough?

(V.92 is superfluous if you get this far, but by now you're already a legend. Go for it?)

 

[tradde]

I got rid of all my modems long ago. I had many. From the top of the line Courier as I ran a BBS, to many not so good. I can't imagine going back to those. Telnet'ing into a BBS is one thing, but I can't imagine the pain of trying to dial in today. Whatever, you do what you enjoy.

 

[Unknown_K]

I have a few internal and external modems sitting around from large take it all or nothing hauls plus what I used back in the 90's.

My 286/12 came with a 2400 baud I used for local BBS (and not so local) and then I upgraded to a 14.4K I think. The warez BBS's had some oddball modems for 16.8K and 19.2K speeds that are probably collectable before everyone used 33.6K and finally 56K.

External models might be collectable, Winmodems not so much. Also have some internal modems that were of decent quality forget who made them.

I have a Commodore 300 baud for the C64 series, some external mac ones that used the Apple serial port plug, and a funky Apple 1200 baud model.

How many people still have old copper landlines in use these days? From what AT&T is charging for a line these days I assume not many.

 

[RetroHospital]

Getting back to the OP's ( @fjellebasse ) question ,

I'm very interested in vintage modems. It's probably because I helped setup the first ISPs in my country and worked on the first copper leased lines during my electronics studies. So i've seen it all, professionnaly speaking.

Everyone above talks about public copper lines, one guy mentions phone line simulator (which are indeed super expensive) but nobody mentions PABX and home/small office systems from back in the day. Also I confirm V32/V90 over IP lines doesn't work well.

In my lab, I've got two PABX (i'm not sure if this word/acronym is in wide use in the US, it is in europe, I mean a small office private exchange phone system) and this allows you to have your own phone lines, in your country's own standards (voltages, ring tone, etc) for very very cheap.

These can still be found very easily on ebay, for let's say 30 EUR/$ you can find a 4 or 6 lines PABX, and these work great to experiment with vintage modems. You plug your device and call line 1 with line 2, usually by just "ATDT2")
I've got a simple one, and a programmable isdn one. You can also assign them actual phone numbers, add a real phone in the game (for more fun), etc. Possibilities are endless - heck - you could actually connect it to your real PSTN line if you wanted toand "DIAL 9 to get out" .

Look for "tiptel home" on ebay for an example of what i'm talking about (this brand is probably specific to continental europe, but I'm sure there are other brands for the other countries for our readers, if someone can tell a typical name for a US pstn PABX that may help others)

Some PABX can be multi voltage, some support US and european voltages/devices/ringtones (it's just a jumper), it's best to look for the PDF documentation of the devices and learn about them before buying them. Also, modems are usually much more tolerant to oddities in the voltages/ringtones than actual phones from the era. (I've never had any issue connecting a US modem to a EU PABX.)

The simplest ones (like the white one below) are "plug an play" and require no configuration. You connect them and usually start dialing "ATDT2" from line 1 right away.

Hope this helps

 

[djg]

if someone can tell a typical name for a US pstn PABX that may help others

Think PBX is the US term. If anyone knows what US box I should be looking for like the tiptel post it. I got some cheap VOIP adapters and set up with Asterisk. Was able to test what I needed but didn't work well with modems. Picking up a cheap small analog unit would be good for future playing.

 

[RetroHospital]

Just for completeness, to some extent, for just two modems, you can tune the init strings so that one answers to the other. However this setup has serious limitations, and I've got pretty bad results with it unless you're connecting two identical modems. And even so you don't get the full negociation, dial tone, it's just not the real thing to me.
It is also somewhat possible to re create a phoneline with a battery and a step up converter but this has again it's own limitations, and it's complicated.

The great thing about PBX system is that it emulates whatever was the line voltage of your country, so you can use it for a variety of things , not just modems but also phone, fax, etc. It's also easy to debug the ATA (answer) strings by just connecting a phone and calling the modem line.

Thru my PABX, I've connected a 300bps Tandy Model 102 with a "modern" 56K USR Robotics with no problem. I've also connected a US Apple 2400bps modem to a toshiba laptop with onboard 33K6. For the oldest of stuff (300bps era) you might want to be sure that your PBX handles PULSE dialing, and not just DTMF. Most programmable PBX handle both DTMF and PULSE. The cheapest ones usually do DTMF only.

Anyway, I know it's a bit overkill, but I like it - and it's cheap because those devices (home p(a)bx) have no modern use, so they are really sold for the price of plastic. What's complicated is that when they are sold on ebay people don't really know what they are, so the search terms are not easy to narrow down.

 

[stepleton]

Thanks, I didn't know about this option. It makes sense.

Have you connected together two 33.6k-capable modems through one of these systems? Did you find that they ran at the full rate? Do you notice any latency in comparison to a direct modem-to-modem connection?

I've tried using one of those cheap two-socket Cisco VOIP boxes and found that (a) it couldn't quite get up to 33.6kbps with a Courier on either end, no matter how I configured it, and (b) it wound up introducing a considerable amount of latency to the connection.

 

[RetroHospital]

I suppose this is highly dependant on the PBX model you choose...
But as many of them were made for small office ( businesses ), with fax in mind, my guess is that they all allow for a full rate modem bandwidth on all the lines. At the very least 33k6, probably higher.

I've made proper 56K connections with mine, but I did not try to send megabytes of data thru it Maybe one day if I'm bored

 

[stepleton]

I've made proper 56K connections with mine

Huh! I thought that 56k connections were only possible if one end of the line was a "digital modem" --- that is, if the digital to analog conversion took place on special phone company equipment. See https://en.wikipedia.org/wiki/Modem#56_kbit/s_technologies :

Because it was possible for an ISP to obtain a direct digital connection to a telco, a digital modem – one that connects directly to a digital telephone network interface, such as T1 or PRI – could send a signal that utilized every bit of bandwidth available in the system.

How are you accomplishing 56k connections with your setup?

 

[Agent Orange]

Another blow to the dialup enthusiasts here in Michigan, is that AT&T recently announced that they are retiring copper throughout the state and everything will shift to fiber.

 

[Chuck(G)]

Yup, been running from a fiber-fed terminal owned by CenturyLink. Crazy thing is that they never dropped their wire POTS, even though it was being fed by VoIP in the terminal. One reason for wired service was that if the mains power went out, your phone still worked because the CO supplied 48VDC over the subscriber line. That's gone--even if you pay for the wired POTS service, you get perhaps an hour or so before the battery in the terminal is exhausted. So you keep a cheap cellphone around for the occasional emergency.

 

[RetroHospital]

I don't remember doing anything special for 56K to work. However I might be fooled by the fact some init string report the COM rate instead of the data rate. Honnestly I never tried to break a speed record ; but it's an interesting question. I'll investigate your question a bit.

I did set up my PBX again on my bench for those curious,



And here's my "good old modem connection sound" video for you to enjoy.

Enjoy the audio ! A concerto of dual 33600 handshakes between a MacOS 10.4 on a Powerbook G4 (internal modem), and a USR Sportster MessagePlus connected thru DB25 serial on a Toshiba 420CDT using Norton Commander's terminal.
As discussed above, "Phone line emulation" here is a 3 port home PBX and the mac just calls number "1".

 

[tradde]

Ah, sounds that I do not miss. But nicely done.

 

[tom.storey]

I have a Cisco router with a bank of digital modems in it along with a bunch of voice and channelised trunk interfaces that was enough to build a "PSTN and ISP in a box". I should dust it off and try it out from my XT, that would be a much more appropriate client.

Last time I used it I tried dialling up from a Mac laptop, but modern OSes, apps and websites are just too chatty and media heavy to use over dialup.