If you own the HTC One on T-Mobile then you should have started to receive the new 4.1.2 update, this is not the Android 4.2 Jelly Bean update. This one has been released to add improvements to the current operating system you already have.
The HTC One T-Mobile 4.1.2 update enhances LTE connectivity and reception and well as improving stability, the build 1.27.531.11 update is 247MB in size and can be installed in two ways.
Users can either update ITA (Over the Air), which released yesterday and all you need to do is wait for the notification to update. You could also opt for the side load from HTC to software 1.27.531.11, just simply connect your HTC smartphone to your PC and then follow the HTC website step-by-step guide.
Android version 4.1.2 software 1.27.531.11 update now includes: LTE and reception enhancements, Software stability and Processor enhancements.
Prerequisites: 50% battery life, Device software is not rooted, Data connection and file size of 247 MB.
Please visit the T-Mobile support page for more information about the HTC One 4.1.2 update; please do let us know if you have received your update yet. If you have received it have you noticed any major differences?