It was shipped with Android 4.4.4. That was before 5 (yeah, I know, stating the obvious), and generally speaking, features new to an OS aren't always enabled by the manufacturer. There's a possibility this is the case. I've had it happen with various phones throughout my Android tenure. It happens with iDevices, too, although, not as often (WiFi Calling is the big one I know of, but I'm sure there's other things not enabled in older devices with newer OS)
Just dropping by to see if you gave the steps above a shot.
Let us know how it went afterwards.