HTC devices usually come with Security-ON or S-ON, which prevents you from changing the Cellular ID (CID) or Model ID (MID) of your device, flash OTA updates manually and many other things. To put this more simply, if you are the kind of guy who likes to tinker with their phones, you will need Security-OFF or S-OFF. Going S-OFF won’t change anything from the user-perspective, you will still have the stable device you had before and you will get OTAs like before. Also, don’t confuse this with rooting or unlocking your bootloader, those are separate things. For example, my HTC One is S-OFF with locked bootloader and no root. I get official OTAs without any trouble. S-OFF is required when I convert my AT&T HTC One to Google Play Edition or Developer Edition. Follow the following steps to get your device S-OFF.