I don't remember exactly when my iPhone 5 upgraded to IOS 6.1.4, but I discovered a problem earlier this week.
My battery kept draining in about 4-5 hours.
When I investigated, I noticed that on the home screen "Searching..." was being displayed instead of the normal cellular signal strength bars. Also, whenever I selected the Phone app, it asked me to re-enter my voice mail password.
I thought about it a bit and remembered threads I had read on KB about how fast the kindle would drain the battery when it couldn't make a cellular connection.
Crossing my fingers, I held in the power button to shut down the iPhone and then pressed it again to power it back on.
After the boot completed, the normal cellular signal strength bars were shown on the home screen and 3 messages were downloaded.
After 24 hours, the Boost Magic app says around 77% of my battery charge is remaining.