I am using Office XP SP3 on a WinXP SP1 machine and am
having a problem with the way Outlook automatically
formats US phone numbers in certain situations.  

If I open a contact and enter a new phone number, for
example 1234567890, when I tab to the next box Outlook
correctly formats that telephone number as (123) 456-
7890.  However, when I click in the box for that number
and then click on the pencil icon to the right to bring
up the "Check Phone Number" dialog box, then change the
number and click "OK", Outlook adds a "+1" to the number,
like this: +1 (123) 456-7890.  How can I stop Outlook for
adding a "+1" to numbers that are in the same country as
I am?

As far as I can tell, my phone dialing options are set
correctly on the "Phone and Modem Options" control
panel.  My default location is listed as United States
and my area code is correctly entered.

Thanks for the help.