Setup your own Dial-Up Networking Server with real hardware! - YouTube
7XV5820-1AA00 Manual Pocket Modem 56k 3.1
Build Your Own Dial-Up ISP – Now With Modem Pool! | Hackaday
Asterisk Usb chan dongle - YouTube
Dial-up file transfer in Windows 3.1 using Zmodem. | QuickLink II Fax is using a US Robotics Sportster internal 33.6K modem and QmodemPro is using a Hayes Accura serial 56K modem.
Getting a dial-up modem working with VoIP – Peter Mount's Blog