In the Express Dial Options dialogue you can type over the Modem Com Port entry (i.e. do not select it from the list) with the correct port name. You can find the correct port name in the 'Phone and Modem Options' menu in Windows -> Control Panel. The Modems tab displays the modems installed on the computer and the port they are using. Just copy the port name used by your modem into the Express Dial Settings.