AT&T wireless carrier rolled out Android 5.1 lollipop update to HTC One M9 smartphone in USA. The software update will reach the htc m9 mobile via FOTA and requires WiFi connection to download the file. The carrier will send a notification about the Android 5.1 firmware update or the users can also manually initiate the software update from settings > General box > About Phone > Software update. If update is available for the device, you can download and install the software update. The user can postpone the android update maximum 3 times, after that the device will automatically update to android 5.1 lollipop. The download file size of the software update will be 914MB. The new software version will update the Android factory reset protection and improves the smartphone performance

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