Yeah, that is not correct. There are two parameters at play here:
courtesytone - either a valid sound file on the system or the word ‘beep’ (without quotes)
parkedplay - determines which parties (if any) get the courtesy tone when a parked call is received.
As stated above, my research into acceptable values for parkedplay was not definitive, but I believe that a value of ‘none’ is what you want to suppress the beeps to both parties. Another source says it should be ‘no’.