920 SMS backup problem.

Thank you for choosing Nokia Lumia920 mobile phone. As long as you turn on backup, your mobile phone has an available network, and all your short messages will be backed up. I suggest you go to "Email+Account" and press "Sync" before you operate, so as to ensure that all backups are completed. After that, log in the account on the phone startup interface and select the restore point to restore (GPRS network is required).