Maybe these things might help.....
What kind of phone is currently connected to extension 20? If it was a 34D, but later downsized to an 18 or 6 button, functions will be lost.
If you press "FEATURE 00" from the extension, what shows up on the display? (assuming the phone has one)
If you then check each of the programmable buttons do any of them say "pool"?
If it ain't broke, I haven't fixed it yet.