This read-only DisplayString, up to 255 characters, holds the call address this connection originates from, comparable to the digits following an 'ATDT' dial string or the calling number in a D-channel setup message, with format depending on the switch type; it is a zero-length string when no address is needed, such as for leased lines. An admin reads this to see exactly what originating number or address was used to place a specific call. For example, an admin auditing outbound toll charges could use this field to confirm which local number was used to originate a given connection.