or you could just look under the call coverge option in system...
I don't think ">9.,,,," is a valid extension. Try this- from any phone do (Feature)(20)(1111). That will cancel extension 11s call coverage if it has been set. (Call coverage is not in system programming.)
If that doesn't work do a reset. Considering the age of your system I would do #728 since pulling the plug may cause it to lose all programming.
-Hal