How to Disable the Modem in Your Laptop
When you aren’t using your laptop’s modem, you can turn it off or disable it. That way, the laptop isn't supplying power to a device that you don't use. The easiest way to do this is to click the Power Management tab in the modem's Properties dialog box. Choose the option labeled Allow the Computer to Turn Off This Device to Save Power.
On your laptop, the Allow the Computer to Turn Off This Device to Save Power option may be dimmed so that you cannot check it. This means that your laptop's hardware is unable to manage the modem's power. All hope isn't lost: You can still disable the modem's hardware permanently. Just click the General tab in the modem's Properties dialog box.
At the bottom of the modem's Properties dialog box, on the General tab, is the Device Usage option. From the drop-down list, choose Do Not Use This Device (Disable). That tells Windows to ignore the modem, which means that you save power and that you cannot use the modem to connect to another computer or to the Internet or to send a fax (unless, of course, you enable the modem).