How does itools import SMS into Apple's mobile phone?

Use itools to export SMS as a file in XXX. CSV format.

Use itunes to create a local backup, and use itools to open itunes backup management.

Double-click to enter SMS, and double-click to open sms.db file.

Select Import csv file, import the file exported above into SMS in itunes backup management, and click Save.

Restore in a large number of backups or simply click Synchronize to the device.