You might consider getting CE Reg Editor (freeware) and looking at the keys. Once you see how they change, then in becomes clear what you need to do in order to change the setting without opening the control panel.
i.e. this is the sound file that is played when an audible ring is enabled, but there are other values under this key that also control if the sound is set to play and at what volume.
[HKEY_CURRENT_USER\ControlPanel\Notifications\Phone]
"Wave"="
\\Windows\\Ring-Innovation.wma"
Best regards,
-boggsie