I doubt there exists any Vista drivers for this device.... it just barely was supported in Windows XP 32-bit. This thread only contains links to Windows XP and older Windows OS's but it might contain enough data about the device for you to find something that will possibly work:
Very few modem manufacturers are even left in business since broadband has arrived on the scene. And they certainly won't ever write drivers for modern Windows OS's for older devices.... it's just not profitable for them to do so. Apply some common sense and it will make sense.
You can see what driverguide and staff members have uploaded by visiting this webpage: http://members.driverguide.com/list/company1694/