Amazon.com: USB 56K Voice Fax Data External V.90 V.92 Modem With Dual Ports, Compatible With Windows 98SE/2000/ME/XP/Vista/Win 7 and Support Auto-Dial, Tone and Pulse Dialing, Auto Answer, Auto Retrain (Black Color) :
Modem US Robotics 5633 - Usb 56K | eBay
U.S. Robotics USR5633A 56K Fax Modem USB Model 5633 External Working No Cables | eBay