I have a flash voicemail system that when a caller is transferred to a user's personal mailbox and they press zero for the operator they hear "the operator is not available." Is this programming that I have to change in the voicemail programming or something I have to change in the phone system programming? Also, callers that are answered by voicemail are sometimes recieving a squealing noise almost like a fax tone. What noise does the Flash voicemail emit when both ports are busy.