T420: Linux Driver for Modem (RJ45 Dialup)

[andrewferguson]

I while ago I was thinking that it would be neat to learn more about the specifics of using dial-up modems (I'm too young to have learned how they worked in any detail). In particular, I'm interested in learning more about the Hayes Command Set (AT Commands).

My first thought was to dig out my BBC Micro and serial modem, but that would be a bit of a faff and I'd have to deal with finding a suitable monitor, hoping the PSU caps are still working, etc... I then remembered that my T420 has a RJ45 modem port on the back. Unfortunately (or fortunately, in my opinion) it's running Linux (Debian 9 Stable) - I haven't managed to find any mention of what drivers / software I'd need to make the modem work. The vast majority of webpages are about the cellular modem, whereas I'm interested in the RJ45 dial-up one.

Has anyone had any success in using the dial-up modem in the T420 whilst using Linux?

[axur-delmeria]

IIRC most Thinkpad modems have Conexant chips. There's a Linux driver at http://www.linuxant.com/drivers/, where the free version was limited to 14.4 kbps, with a paid license to get full speed. But since dialup modems are now obsolete, the company has ceased further development and released the full version of the driver.