In general, FreeTextSMS.net Client app installed in your Android phone will syncing your phone's SMS one by one in background and you don't need to care about it by yourself. In sometimes, when you use FreeTextSMS.net web application
Smart Sync function will only import missed missed text messages from Android to server's database.
This method is more safe and quicker than
Force Sync below.
The hidden SMS messages already exist in server's database will still be hidden and not modified.
You can see
Smart Sync button in Android SMS page's middle column - a round icon of phone plus refresh sign.
Force Sync function will remove all SMS messages from server's datbase first, then import all SMS messages from your Android phone once again.
This will let you sync all data from your phone just as you first time use FreeTextSMS.net/web application.
You can access
Force Sync function in Settings page -
START SYNC ANDROID SMS button below. Click this button will trigger your Android phone to upload all of SMS messages to server. It will take ten seconds or more time to complete.