On all 3Com NBX chassis, the Serial Number is specifically registered to the back plane of the unit. In order to transfer 3Com NBX chassis licenses and database to a back-up hard-drive ... a.k.a. Field Replacement Unit ..., what you need to do is as follows: 1) Back up your licenses, 2) Back up the database, 3) Transfer and / or upgrade the hard-drive, with a compressed .TAZ file, 4) Restore the licenses, and ... 5) Restore the database. Call us at 800-544-0059 if you have any further questions.