This is a very popular late 2003 modem made by Motorola. The Motorola C650 Modem is very similar to the Motorola C350 but with more features. The file is listed below and note that this driver was made for a Windows XP operating system.
If you are going to try to run this modem on a Windows 7 operating system then you have to look at running it in Windows Compatibility mode. This is explained here for another device with the same problem.