So here's an interesting issue I ran into...maybe other people have too? Seems very isolated but...
I have a Lumia 920 on ATT. I also have an iPhone 5.
Today I decided that I wanted to go back to my Lumia, so I went to a store, had the sim swapped out, phone was off everything..blahblah.
After I powered the Lumia up, I went to go set up my voicemail. I tapped on phone, then the voicemail application...it said it didn't detect my voicemail number...okay, weird...so I rebooted the phone, cell networks are very odd.
After my phone turned back on, I did the same thing, my phone dialed me into voicemail and I entered my PW and hung up to get the Visual Voice Mail prompt. I entered in my password, and the phone froze and rebooted!
It did this several times.
Oddly enough, after I uninstalled Skype (I finally saw the goofy syncing bug) and soft-reset the phone, everything was working as intended.
I had never seen this issue previously on this phone or any other phone I had.

Perhaps this is an isolated SW issue and should be perma-quashed by that OTA we're supposed to be getting next month?
Any ideas?