You can't have the call ring at the phones, and then cover to the GENERAL mailbox. You CAN have it ring at the phones, and then cover to a SPECIFIC USER'S mailbox.
The General Mailbox is designed to receive calls from the Auto Attendant, at night, when the caller presses 0 or nothing at all. By using a special General Mailbox, the messages end up separate from the Operator's own personal mailbox.
If the "Call Answer Service Operator" is set to the default 768, and the Dial-0/Timeout option is "Transfer to the Call Answer Service Operator", the call will go to the phone connected to the 1st extension port, which is your Operator phone. BUT, it will not cover to other extensions, AND it will not cover to voice mail.
If you either change the CASO to the Operator's actual extension number, OR, change the Dial-0/Timeout option to actually transfer to the Operator's extension number, the calls will cover to the other extensions, and will cover to the Operator's personal mailbox.
BUT, you also have to have the Transfer Return Rings for the AA/VMS set to be higher than the combination of the Operator's Primary, Secondary, and Group Cover rings.
Hope that helps clear things up!!