The update for the HTC One S from T-Mobile will require you to adhere to the standard issue requirements, namely having a stock version of the Android operating system that is unrooted, a minimum amount of 50% battery life and of course, we would recommend you having performed a backup on the HTC One S prior just in case Murphy decides to drop in on the update process. The entire update will weigh in at approximately 49MB, and this OTA (Over The Air) download will be available from now onwards, with the rolling out process completing by February 28th, so fret not if your HTC One S has yet to receive it.