T-Mobile owners of the HTC One M7 smartphone could start seeing a small software update for their device over the next few days or weeks. The download will bring the version number up to 6.10.531.10.
According to the T-Mobile support page, the download is supposed to fix a "call audio issue" with the smartphone. This is not an update to bring the device over to Android 5.0 Lollipop, but HTC has previously confirmed that HTC One M7 users will get Lollipop sometime before the end of January 2015.
Source: T-Mobile Thanks to capellmeister for the tip!