Well, to be honest, that is not a friend code for Wii Sports. Wii Sports does not allow you to use the Nintendo Wi-Fi connection to play with others over the Internet.
That friend code is more than likely to be your system code, considering it is four digits longer than most, if not all, friend codes for games of the Wii.
(The system code is used to send messages to other people. You must add them and they must add you to do so. It does not just allow you to play online in any game though.)
