The Country/Region settings may be missing when you view the properties for a modem on a computer that is running Windows Vista SP1 or Windows Server 2008
Assume that you are running Windows Vista Service Pack 1 (SP1) or Windows Server 2008 on a computer that has a modem connected. When you view the modem properties in Control Panel, the Country/Region settings may be missing on the Advanced tab. Therefore, you cannot configure the Country/Region settings for the modem.
This problem occurs intermittently. After you reinstall the driver for the modem, the Country/Region settings may reappear.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB955991.