Since the update last week (?) I have had my 8X not receive calls on two different occasions.
Both times it had been sitting on my desk and had not been used or checked for maybe an hour or more.
When I did unlock the phone and started make a call I started to get voicemail alerts.
When I called the people back they claimed to have been trying to call me several times only to go to voicemail.
The phone did not display any missed calls.
This did not happen before the most recent update.
Known issue with the phone or perhaps a service issue? I have had trouble at this address, where this problem happened both times, but t-mobile has fixed the issue and I get pretty good 4g service daily since.