.STG File Extension
File TypeActiveSync Backup File
What is an STG file?
Backup created by ActiveSync, a program used to synchronize PCs with mobile devices; contains a backup of all mobile device files, including contacts, notes, and calendar data; typically seen with the filename backup.stg.
NOTE: Microsoft removed the backup and restore feature beginning with ActiveSync version 4.2. To recover backup files with ActiveSync, use version 4 or an earlier version that is compatible with STG files.