This read-write value sets the default caller category (such as subscriber-without-priority, subscriber-with-priority, maintenance-equipment, charge-meter, operator, or data-tx) that the Outgoing MFC register reports when the far-end Incoming register requests it. An admin configures it because this information about the caller may not otherwise be available from the call itself, so it must be provisioned administratively for the general case. For example, an admin would leave this at its default of subscriber-without-priority (1) for ordinary residential lines, but set it to operator (5) on a trunk dedicated to operator-assisted calls.