On a new installation of Windows Vista with a new installation of Office Outlook 2003 or Office Outlook 2007 has consistently returned an annoying pop-up window for me. By default, Windows Vista installs the Telephony service for my laptop, which has a built-in modem. When I first try to add a new phone number to an Outlook contact, Windows jumps in to tell me that I haven’t configured my area code for the modem. Any attempt I make to cancel this dialog box returns a Confirm Cancel window. These interfaces are shown in Figure 1.
It doesn’t matter whether I select Yes or No in the Confirm Cancel window, I am immediately returned to the Location Information box demanding a source area code. It is Windows and not Outlook that is requesting this information. I see two options for halting this frustrating loop. The easiest is to enter a home area code in the appropriate field in the Location Information box and click OK. This covers up the symptoms without solving the underlying problem. If you don’t use the modem at all, you can resolve this pop-up request by stopping the Telephony service and setting the value to Disabled. This is easily done if User Account Control has been disabled first. Otherwise, to stop the Telephony service, you need to set the Startup Type for the Telephony service to Disabled, and then reboot the workstation. Windows will no longer need a home area code then.
Learn more from "Outlook 2007 vs. Outlook 2003" and "How do I disable COM add-ins in Microsoft Outlook 2007?"