I'm trying to disable the voicemail extension from being accessible via IVR. I have read that there is an option called "IVRDONOTCALL" in the Settings > Advanced > Custom Parameters. I have entered the voicemail ext (9999) and another extension (1234) and as per instructions, started the entire phone system. But when I dial-in (from outside line) and get to the IVR, i am still able to dial both 9999 and 1234. Can anyone help with this IVRDONOTCALL problem or offer another solution to blocking external access to voicemail?