attendant answers saying answering by operator and transferring.
This is the behaviour when one or more VM ports are not assigned to Hunt Group 7. The unassigned port(s) are receiving immediate ring on the incoming call, and not being filtered by way of Hunt Group 7 are not receiving Mode Codes that indicate which service to answer the call with. So the fallback action is "Transferring to Receptionist" and sending to Ext. 10. Ext. 10's voicemail will answer if Ext. 10 itself does not.
The message recorded as Mailbox 10's greeting is probably similar or the same as the Night Greeting (I've had customers record the AA greeting in Mailbox 10, and also in the wrong AA)
First, confirm the correct extension numbers for the VM ports. Don't relay on the documentation, it is not correct for ACS and especially not for ACS R7. The VS Mail module is seen as a 6 port module, the VM ports are the last 2 or 4 ports on the module.
Here's an example of VS Mail in Slot 1 with ACS Processors
Confirm that ALL of the VM port extensions are assigned to #505-7 and that NO OTHERS are in that group. Confirm by calling Intercom 777 several times in a row and see that VM answers on the first ring every time.
With that resolved, confirm that #206-7-{Line Number} is set to 1, and that #208-{Line Number} is blank.
In the VS Mail, confirm that there is no Line Ownership assigned, which would set a line to be answered by a mailbox instead of the Auto Attendant. Confirm that all of the lines are assigned to Auto Attendant 1, and that the Day and Night recordings are what you are expecting. Call Mailbox 10 and listen to the greeting, make sure it is what you expect (leave a message, not a menu of options)