Droid Maxx, replacement phone for a phone with a damaged screen. I've spent hours on the phone with customer service and no solution. Have wiped the cache and done a factory reset. No change. Still cannot make or receive calls and get the "mobile network not available" message. But texting and 4G data work perfectly. Suspect that it's a problem with the "phone" app (the dialer) as it is half the size as the same app on an identical Droid Maxx. Is there a way to reinstall the phone app? Or perhaps force a reload of the last system update?