Um... dude. Actually they can. They just have to use the Support Desk instead of the /tell system. And if a System Administrator needed to contact you while you were in an Instance, then I am pretty sure they could bypass the "no /tell's while in an instance" black out if they really wanted to. System Administrators are just below the Developers on the hierarchy of power within the game. G.M.'s don't have the kind of power that a System Admin has.
