T-Mobile has said that a fix is on the way for an issue that affects the HTC One S' battery life when using the Wi-Fi calling feature. We hadn't heard much about the problem ourselves, and didn't run into it in our review, but the carrier says that it'll be resolved in a forthcoming software update anyway. In the meantime, T-Mobile advises keeping your phone plugged in when making calls over Wi-Fi. No word on when that update will be released, but it's good to see the carrier getting ahead of the issue — as well as drawing attention to an under-supported feature that doesn't seem to get much love from many.