“Line disconnected” means the system detected that the phone line is disconnected
(the other side hangup, modem drop call, etc) before message playing.

“Line occupied” means the phone line the modem trying to call is in use.

“Line busy” means the phone number the system is calling is busy.

“No answer” means the no one answers the call. There is no answering machine or voice mail either.

“call succeeded but with no confirmation” means that call get through, but the person answers the call does not press any confirmation key. He might hang up the phone in the middle of the message.

“auto disconnect after x rings” means the system disconnect the call after the maximum rings are reached.