Xact XD6451 User Manual page 39

TEXT MESSAGING (cont.)
6 0 . If an SMS is received with incorrect sub-address - after checking the FSK data and determining that the SMSC number is correct but
the subaddress that has been sent is incorrect, subsequent ring bursts will be audible.
6 1 . User master reset via Set Base menu will not clear SMS data including users' mailboxe s .
Full factory reset (press and hold KEY_STAR) while inserting the battery) will clear all SMS data including users' mailboxes.