This read-write value has only a single defined enumeration, add(1), for this Caller ID entry's administrative status, suggesting this object is used purely as a trigger to add the entry into the switch's caller-ID table rather than a true multi-state up/down toggle (removal is presumably handled by other means, like setting isdnCallerIDAddr to null as with isdnAddr). An admin provisioning a new caller-ID screening entry would SET isdnCallerAdminStatus to add(1) as the action that commits the entry, rather than expecting to toggle it between multiple operational states afterward.