Refurbished: 3COM COURIER V EVERYTHING 56K V.90 MODEM 3CP3453 (FRONT PANEL IS MISSING), W/ ADAPTER - Newegg.com
US Robotics 00568903 Sportster 56K V.90 Modem for Macintosh, No AC Adapter | eBay
What caused the iconic old dial up internet tone from the 90s? Did someone design that sound digitally or is that some sort of analog tone generated from hardware? - Quora
Old internet dial up 56k Modems. Can you hear it? : r/nostalgia