Modem sound is usually controlled through the use of an initialization string. With it, you can control several different parameters of your modem. Most modems follow a standard of initialization codes for controlling parameters, but yours may be different, so this may not work. Hunt around in your modem's properties for a text box labeled "Extra Settings". If there currently is a string in there, leave it, but include &M0. If there is no string in there currently, use the full string AT&M0. That will set your modem speaker volume to nothing. This will work on most modems, as I said before. If it doesn't work for yours, do a google search for your modem's name and "init string".