Nobody ever done this?

I assume you mean ESP with special bbs firmware, afaik (havent tested myself) this is a special firmware that will only work for that particular purpose
you will need different one (stock offered that) for ordinary serial-wifi bridge

Wrong forum. As per the pinned topic in this forum: "This forum is for running old Windows games on NEW (supported) versions of Windows" Ask old hardware and configuration questions in Marvin. Marvin, the Paranoid Android

Moved.

I'd also love to get internet access into some dos and windows 95 machines through using a dial-up modem between retro machine and modern internet connected machine.

Closest i've got, is simulating hayes modem on my modern computer over serial port for retro pc. Phone nr becomes a url and so you can connect to specific bbs or other server, one at the time.

Have also been thinking about how to realize this. Basically you need three things:

- PPP client with dialup modem. I.e. any period-correct PC from the mid 1990s.
- PPP server with modem. This doesn't even need to be significantly different hardware, but it needs software to listen on the line.
- Something providing line voltage.

Point 3 is the biggest challenge as POTS lines tend to be dead these days. But a quick chat with some voice engineering colleagues who have been in the business since those days suggested this could be pretty easy: take a home PBX. Even the simplest versions (where you dial 1-5 for internal lines and prefix a 0 for external numbers) can generate line voltage independently of an outside line. In that case it boils down to:

PPP server with modem -> POTS -> Line 1 on PBX | Line 2 -5 on PBX -> POTS -> Clients with modem.

kikendo wrote:

So instead of setting up a PPP/Slip server on a serial or whatever other physical port, is it possible to have it open on an IP port? Has anyone done this before?

Use socat to listen on a socket and exec a PPP/Slip server (e.g. slirp) when an incoming connection is made.

collector wrote:

Wrong forum. As per the pinned topic in this forum: "This forum is for running old Windows games on NEW (supported) versions of Windows" Ask old hardware and configuration questions in Marvin. Marvin, the Paranoid Android

I had not realized I posted in the wrong forum, SORRY. Thanks for moving it, moderator.

dionb wrote:

Have also been thinking about how to realize this. Basically you need three things:

This is a bit complicated and only for machines with real modems. The Wifi modem is cheap and convenient, my solution should be much easier to implement. You only miss the handshaking sound 😜
Also I am pretty sure if you have two modems, you can just jack the phone line cord between the two and dial/pick up the "phone". Can you not?

jmarsh wrote:

kikendo wrote:

So instead of setting up a PPP/Slip server on a serial or whatever other physical port, is it possible to have it open on an IP port? Has anyone done this before?

Use socat to listen on a socket and exec a PPP/Slip server (e.g. slirp) when an incoming connection is made.

Hmmm explain it like I am five. I have no idea what socat is.

kikendo wrote:

[...]
This is a bit complicated and only for machines with real modems. The Wifi modem is cheap and convenient, my solution should be much easier to implement. You only miss the handshaking sound 😜
Also I am pretty sure if you have two modems, you can just jack the phone line cord between the two and dial/pick up the "phone". Can you not?

No, you probably can't as you need to have a voltage on the line and a regular modem doesn't supply it.

As for complicated - you asked for the good old experience. Well, from client side this is 100% the same as in the day - just dialling a "1" instead of 0123456789, but doing all the handshaking we so loved not to have to do anymore when we upgraded to DSL/Cable. I also don't see it as complicated, you take an off-the-shelf device which requires no config at all, and one I fully expect to find for EUR 5 or so at a thrift shop or juble sale once I seriously start looking. Here in NL the local telco KPN had a "HomeVox" range that was pretty popular. Then you just need two PCs with modems, one of which can host PPP services and route the connection onto IP. My home server can do that, I just need to find a PCI hardware modem for it (WinModems and Linux tend not to mix well).

kikendo wrote:

Hmmm explain it like I am five. I have no idea what socat is.

It's a linux utility that can connect a program's input/output to a network socket (among other things).
> socat -d -d tcp-l:6666,reuseaddr exec:'slirp -P nozeros'

will listen on port 6666 for a connection, and when one is made it will spawn an instance of slirp with its input and output redirected to the new connection.
So you set your dial string (or whatever) for the wifi modem to connect to port 6666 on the host pc and it will end up talking to slirp (and hopefully establish a PPP connection just like a dial-up modem).

dionb wrote:

kikendo wrote:

[...]
This is a bit complicated and only for machines with real modems. The Wifi modem is cheap and convenient, my solution should be much easier to implement. You only miss the handshaking sound 😜
Also I am pretty sure if you have two modems, you can just jack the phone line cord between the two and dial/pick up the "phone". Can you not?

No, you probably can't as you need to have a voltage on the line and a regular modem doesn't supply it.

As for complicated - you asked for the good old experience. Well, from client side this is 100% the same as in the day - just dialling a "1" instead of 0123456789, but doing all the handshaking we so loved not to have to do anymore when we upgraded to DSL/Cable. I also don't see it as complicated, you take an off-the-shelf device which requires no config at all, and one I fully expect to find for EUR 5 or so at a thrift shop or juble sale once I seriously start looking. Here in NL the local telco KPN had a "HomeVox" range that was pretty popular. Then you just need two PCs with modems, one of which can host PPP services and route the connection onto IP. My home server can do that, I just need to find a PCI hardware modem for it (WinModems and Linux tend not to mix well).

Could you use an Arduino or Raspberry Pi to act as an intermediary between the two modems? A kind of homebrew pbx?

dionb wrote:

Have also been thinking about how to realize this. Basically you need three things: […]
Show full quote

Have also been thinking about how to realize this. Basically you need three things:

- PPP client with dialup modem. I.e. any period-correct PC from the mid 1990s.
- PPP server with modem. This doesn't even need to be significantly different hardware, but it needs software to listen on the line.
- Something providing line voltage.

Point 3 is the biggest challenge as POTS lines tend to be dead these days. But a quick chat with some voice engineering colleagues who have been in the business since those days suggested this could be pretty easy: take a home PBX. Even the simplest versions (where you dial 1-5 for internal lines and prefix a 0 for external numbers) can generate line voltage independently of an outside line. In that case it boils down to:

PPP server with modem -> POTS -> Line 1 on PBX | Line 2 -5 on PBX -> POTS -> Clients with modem.

That's how I did this in an experiment a while back. PowerMac G4 Quicksilver running Ubuntu Server with the appropriate programs/scripts as the PPP server, a cheap internal home phone switch from the thrift sitting between the server and the client, and then finally in this test, an iBook Clamshell. After some fiddling, I got it to go online, which was cool. Still planning on setting up one of my HP thin clients for this use in a more permanent way. I also have used DreamPi, a similar solution for the Dreamcast modem utilizing the Raspberry Pi with an USB modem as PPP server, so it can connect to Dreamcast Live, a fan-run service to allow you to play online games on the Dreamcast together like it's 1999.

Someone has obviously found a way to do that, because the Dreamcast (which uses a modem) has had a recent revival with the Dream Pi project. (Woops... a few minutes too late for that revelation.)

I've been looking at this a little bit from a technology perspective, and while the client side is ubiquitous, the POTS side is not at all. Two modems wired back-to-back will not detect a dialtone, and so will not dial. You can use an AT command to disable detection, which will probably be sufficient for most people. Then you just need one side to answer and do whatever you dialed that computer to do. (E.g., start BBS software, or redirect network access via SLIP/PPP, etc.)

But, I've been trying to figure out how to become an internal SP, of sorts. As a network engineer, I started looking at old Cisco WIC modules and such. Lots of modems (which need POTS), and lots of cards to provide FXS ports, but they lack the DSP to act as a modem. They're meant to digitize the audio and hand it off as a SIP connection or similar. You could, in theory, have a SIP gateway with soft-DSP to speak modem, but I haven't found such a product yet. So, using an old Cisco 1U router to be a dial-up ISP in a box is probably not happening. But I think you could get two ATAs (or FXS ports) to connect two phone lines with modems on them, as long as you make sure the codecs are data-friendly. With an external modem attached to one, and via serial to the router, you could probably get the dial-up ISP thing to work.

The "big-guns" approach is to actually set up a PBX (of any size, from home office to telco), or if you want 56K support, get a digital modem bank and a T1 CSU and all that. Takes some space, some power, a considerable amount of telco prowess, but it creates real POTS service.

That's as far as I've gotten. It's a very back-burner project for me.

Hamby wrote:

[...]
Could you use an Arduino or Raspberry Pi to act as an intermediary between the two modems? A kind of homebrew pbx?

The point of the PBX isn't to route,it's to provide line voltage, not much more. It's just the cheapest, easiest device I know of to do so. A Pi can't do that on its own.

SirNickity wrote:

[...]

But, I've been trying to figure out how to become an internal SP, of sorts. As a network engineer, I started looking at old Cisco WIC modules and such. Lots of modems (which need POTS), and lots of cards to provide FXS ports, but they lack the DSP to act as a modem. They're meant to digitize the audio and hand it off as a SIP connection or similar. You could, in theory, have a SIP gateway with soft-DSP to speak modem, but I haven't found such a product yet. So, using an old Cisco 1U router to be a dial-up ISP in a box is probably not happening. But I think you could get two ATAs (or FXS ports) to connect two phone lines with modems on them, as long as you make sure the codecs are data-friendly. With an external modem attached to one, and via serial to the router, you could probably get the dial-up ISP thing to work.

Modulating digital into analog, then digitizing that again, re-modulating into analog before demodulating again at the receiving end sounds like an awfully and unnecessarily complex procedure that will just introduce errors (even if you have a friendly SIP codec).

The "big-guns" approach is to actually set up a PBX (of any size, from home office to telco), or if you want 56K support, get a digital modem bank and a T1 CSU and all that. Takes some space, some power, a considerable amount of telco prowess, but it creates real POTS service.

That's as far as I've gotten. It's a very back-burner project for me.

These devices I'm talking about are far smaller, things like this:

Technically they're PBXs, but they require no knowledge to set up and are a minor power drain. If you want to go wild with full PBXs to set up a regular POTS service by all means do, but it's certainly not necessary.

dionb wrote:

SirNickity wrote:

But, I've been trying to figure out how to become an internal SP, of sorts. [...] They're meant to digitize the audio and hand it off as a SIP connection or similar. You could, in theory, have a SIP gateway with soft-DSP to speak modem, but I haven't found such a product yet.

Modulating digital into analog, then digitizing that again, re-modulating into analog before demodulating again at the receiving end sounds like an awfully and unnecessarily complex procedure that will just introduce errors (even if you have a friendly SIP codec).

Yes, and this makes me wonder whether it makes any sense to attempt to set up a private (only for self-use) "ISP" by attaching a PPP server via an old but good USR modem to the "POTS" outlet of my AVM Fritzbox 7490, which converts that to SIP.

My use case would be to hook up my old Nokia 9110 to the internet. It uses a 9600bps analog modem via GSM.
Remarkably, the 9110 is the only cellphone I know of, which is able to receive faxes. Its successor Nokia 9210 dropped that functionality again, as it apparently was not as reliable as expected.

So in this case, I'd be curious whether analogmodem<->GSM<->SIP<->analogmodem could work at all...

I have done this exact thing by setting up a dial-up internet server on a WinXP machine (requires XP Pro, will not work on XP Home) and connecting a phone line directly from the modem on one computer to the modem on the XP machine, with a third little box in the middle to generate a ring signal so the XP box knows when to answer. The XP machine would then share its internet connection via wifi over the modem.

Video of my setup: https://www.youtube.com/watch?v=jpey-EQJe54

I neglect to give details on how I set up the XP machine, I hope to remedy that in a followup video.

I have seen people do something similar using some offline VoIP adapters, but I have no experience with that.

Um guys, OP just wants to get PPP working over TCP/IP. Nothing to do with real modems and such.

dionb wrote:

Modulating digital into analog, then digitizing that again, re-modulating into analog before demodulating again at the receiving end sounds like an awfully and unnecessarily complex procedure that will just introduce errors (even if you have a friendly SIP codec).

It totally is. My initial idea wasn't to have two modems connected to each other via SIP. It was to have a WIC receive the analog modem signal and convert it into serial data accessible via a logical serial interface on the router. The SIP thing is a clunky workaround but it's also very similar to what happens when two analog modems call each other through POTS.

dionb wrote:

These devices I'm talking about are far smaller, things like this:

Technically they're PBXs, but they require no knowledge to set up and are a minor power drain. If you want to go wild with full PBXs to set up a regular POTS service by all means do, but it's certainly not necessary.

Neat. I've never seen anything like that. However, there's a good chance they're digital -- since ASIC codecs would likely be cheaper than multi-line analog switching. So... we're back to modulating digitally modulated modules again. 😉

jmarsh wrote:

Um guys, OP just wants to get PPP working over TCP/IP. Nothing to do with real modems and such.

Does OP? I have no idea what a WiFi modem is, so that's entirely possible. I didn't quite understand how dial-up and serial ports equated to opening "an IP port" either. I assumed if the PC in question had TCP capability, there wouldn't be much need for a serial modem of any sort, unless the goal was to have a modem for the sake of fun.

Hamby wrote:

Could you use an Arduino or Raspberry Pi to act as an intermediary between the two modems? A kind of homebrew pbx?

You could use a microcontroller or embedded device (Arduino, Raspi, ESP8266, etc) to fake the Hayes command set and forward serial traffic (internally or externally) to a PPP server. This would act as an external modem without having to use an actual phone line.

This guy made a device like that, tucked into an old USR case:
[Build Log]: Dimension95 - A Retro DOS/95 Build & Internet Project.