Operating System: All Windows Versions (Note: might work with other versions of this os.)
File: ESS ES56T-PI
The modem is identified in Device Manager as an 'ESS ES56T-PI Data Fax Voice Modem', and uses the ES2898S and ES2818P chips. What is MOST confusing is the 'Atech ATS-256' sticker on it!! I tried loads of drivers posted under Atech ATS-256 but none worked - (I have also seen other Atech modems with Rockwell chipsets). There was another sticker with '5634PEW' on it, which I discovered is the Archtek Model number. Go to their website and you'll find the drivers !!! I installed these and they worked first time. The difference is these drivers install an 'ESS Modem Device Controller' in Device Manager, as well as the entry for the 'ESS ES56T-PI Modem'.
Hope this is useful and saves you hours of searching.