My first iPhone 5 had the common power button problem (stopped functioning). Now that the replacement is out of warranty I can turn the phone off but not back on (need to plug it in to the charger). The button itself seems to function fine. Weird.
In 2000 we owned a pair of Sony Ericsson R320s. They were horrible. I remember acknowledging missed calls to suppress the terribly annoying voice mail reminder beeps but it always refused to shut up. It would just continue to beep until you listened to the voicemail.