I'd like to recreate old dial-up experience but without actual calling telephone provider's dial-up number. So I thought, maybe a linux machine could host ppp server and accept dial-up calls from win98 machine via the RJ11 wire and share Internet connection with it. Is something like that possible?
You would need to interface the two modems with some form of telephone exchange system. Just hard-wiring them together won't be enough - the PSTN (telephone system) actually provides power through the wires for such things as ringing signals and such.
The closest you could get without a telephone exchange would be to just use a Null Modem cable to link two serial ports together and do away with the actual dialing part of the experience.
You might be able to do this if used a phone line simulator - a device that feeds the device the current that phones run off - jagshouse has an article that details how to build them.
A quick google search also indicates that there's prebuilt, commercially available models of the same device, if you were not DIY inclined.
The line simulator should replicate the effect of the two phones being connected over a conventional phone line, and allow you from communicate from one to the other with AT commands.
Linux has supported
So if all you want to do is play around with
If the "ppp client" is Windows, Windows insists that the other end is a modem. What this means is that Windows will always try to send "AT" commands over the serial port before starting to talk ppp over the serial port. AT commands are locally understood by a modem, but are not part of ppp. Not to fear, Linux "ppp" supports a "chat" script that can respond as Windows expects.
Here is an excerpt of the
Under Linux, typically your modem would be attached via a serial port, or that would be emulated by a PCI card or onboard chipset (externals work much better with Linux). The modem implements the V.92 or whatever protocols actually making sound over the phone line.
If you want to simluate that part of it, you can try Softmodem. This will take an audio input and output via JACK and actually do the audio "modulate/demodulate" part a modem is supposed to do (limited to 14Kpbs I believe, though). I couldn't get it working on my server but I don't have a lot of experience with JACK (or an actual audio device on the server other than the PC speaker...)