Limitations of UPnP in Windows XP

On Windows XP pro with ICF actived.
When i login as Administrator User, all function of Windows Messenger work (video/audio ..etc..)
But when other users (users that haven’t administrative privileges) try to make video/audio conversation, ICF block…
Microsoft says : ”
In Windows XP, outgoing calls from Windows Messenger will not work when ICF is enabled on the local interface and the user does not have administrative privileges. This feature will work correctly for users that have administrative privileges. ”

But, i don’t want users have administrator privileges ! (only one Administrator !)

Any solutions ? unless open all UDP 5004 and 65535 or change for another firewall ??

Sevices access rights can be change for allow normal users to manage ICF ?

thanks !