The system settings can be programed by using a proprietary telephone (PT) with a display, e.g. the KX-T7730. An authorised administrator connected to extension jack 01 can access system programming. Press [program] [*] [#] [numeric password] then the numeric [program code]. All this info in the system admin or feature user guides. Plenty of copies on the web. If you have a maintainer, talk nicely, and he may give you PC access via the USB port.