You probably installed the Fax.
Start/All Programs/Accessories/Communications/Fax/Fax Console
From Fax Console: Tools/Configure Fax/....<next><next>Enable Receive
<----remove checkmark
If you did not install the Windows FAX or any other software, then you can
open Hyper Terminal (found same place as the FAX folder) and type ATS0=0.
You may not see anything except 'OK' after you type this command followed by
'return'. This will tell your modem on how many rings it should answer where
0=not answer.