HTC released a service pack for several of its devices (at least the M8, probably more), and it evidently disables the ability to place phone calls. The service pack release is listed as nothing more than “bug fixes” and all the reviews on the front page from today tend to indicate that the service pack disables the ability to place phone calls.
The evident fix as suggested by one reviewer is to turn off the wireless and reboot the phone, suggesting that there may be a problem with the WiFi calling module becoming enabled and routing the phone calls without you telling it to.
Whatever the case, the update’s running solid 1 and 2-star ratings from reviewers, so if you’re contemplating updating to the newest service pack you might want to hold off.
We’ll update this if I can get more information on what exactly the problem is, for now this is just a warning to stay away from the service pack, and let us know what device you’re on if you’re affected by the no-call issue.
I do not know yet whether you can simply uninstall updates or if the service pack is a one-way trip, but if there’s someone running stock rooted, you might want to make a nandroid, install the service pack from the Play Store, and let us know. A rooted phone can at least nandroid back to a state pre-service pack.
Oddly, I’m on a GPE conversion ROM at the moment and do not think this is going to be testable without some efforts.