I'd like to run an old-school BBS that can be dialed into over a real phone line. Unfortunately, I don't currently have the necessary hardware to do so. I had the idea of purchasing a VPS and then using an SIP softphone and some BBS software to accomplish the same task. The only problem is that I can't find anything that emulates a modem. I'm aware of a program called minimodem, but that seems to only work for FSK and doesn't support any kind of handshaking. Ideally the program would create a virtual serial port and take input from / output to a sound device. Does anyone know of any software like this? Thanks!

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    This does sound quite like a question about modern hard and software which should be directed to areas dedicated to such, shouldn't it? Beside that, I'd really recommend to get an old modem and hook it up. After all, it's not the real experience without all the hassles a real modem will insert - the caller having a different modem being the least thereof :)) Maybe using a USB to serial converter. Most modern network (phone) terminals do still allow analogue devices.
    – Raffzahn
    Aug 31, 2021 at 10:24
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    POTS telephony and BBSes are pretty retro, though. Aug 31, 2021 at 11:59
  • @user3840170 True, if that question would be about issues of/with some historic BBS software, or writing a new BBS software on old hardware (not emulation), I'd be eager to welcome it. After all, there is much detail in modem handling that needs a close look - not to mention the pitfalls of various (real) PBX inbetween and/or problems different kinds of modems had to connect and negotiate. I remember having spend countless hours on modem manuals :)
    – Raffzahn
    Aug 31, 2021 at 13:53
  • How do you expect people to connect to your softmodem? Sep 2, 2021 at 21:10

3 Answers 3


There is the Linmodem project, made by (who else) Fabrice Bellard. Unfortunately, it is more of a proof-of-concept than a working, ready-to-use driver, and it has been abandoned in that state in 2000. It barely contains incomplete implementations of four Hayes/AT commands and the V.34 protocol, and has not been ported to the modern Linux audio stack (ALSA), or even the Unix 98 pseudo-terminal interface. Even compiling it as it is under a modern system requires some light patching (mostly adding missing extern specifiers and re-ordering compiler flags).

Nevertheless, for someone willing to spend some time on developing a software modem, this might be a good starting point.


There are people around who are running BBS on dialup and emulated lines.

The answers given in this related question (which is C64-specific) give some sources of software that may be useful to you.
In particular The BBS Corner. However, the site hasn't been updated for a while so you may have to dig around a little.


Not terribly authentic if it is all simulated like that. But more importantly, there is the complication that while much of a modem's capabilities can be handled by software instead of hardware (personally I never found that soft-modems worked very well, but that's a separate issue), the sound card input/output is not going to have the on-off capability and, I suspect (but could be wrong) ring-tone detection needed for a functioning modem. Remember acoustic couplers? They relied on a human being for ring-tone detection and placing on/off hook.

The good news is that eBay has plenty of modems available, many from major brands (e.g., US Robotics), for under $ 20, including some still in their shrink wrapped boxes.

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    "They relied on a human being for ring-tone detection and placing on/off hook." Well, more could be done, like placing a coil below the phone to detect the ring and another to pull a lever to 'answer', while the receiver was already placed firm in the coupler :)
    – Raffzahn
    Sep 1, 2021 at 11:49

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