Update: Apparently the update should also bump HTC One Max owners up to Sense 6. This may turn out to be quite the OTA.
Wi-Fi calling is great for people who still have plans that don't supply an unlimited number of minutes or during those times when cell reception in a particular location is less than stellar, as it lets customers place phone or send text messages over a Wi-Fi connection instead. Sprint started rolling out the feature to a hyper limited number of devices earlier this year, and now the carrier has announced an OTA upcoming enabling the feature for another somewhat peripheral device, the HTC One Max.
The update should bump the device up to software version 3.02.651.5. Aside from Wi-Fi calling, this OTA appears to do nothing else. But really, that's not particularly a bad thing as far as updates go. They can't all be a new version of Android.
Though imagine if they were...
Anyways, the update is rolling out in stages. One Max owners can start checking for it manually, but there's a good chance some will just have to wait it out.