Maybe this helps:
"The access to the sets "Advanced" settings menu is controlled via the MiVB "System Security Management" form of the System Administration tool. Using the "Phone Administrator Passcode" field.
By default when a 69xx series set powers up, the access code for the "Advanced" menu in the 69xx set is 73738 (or RESET by keying the letters) but as soon as the set has registered with an MiVB system it will adopt the value configured in the Phone Administrator Passcode field of the System Security Management form.