iPhone loses SMSs after software update I recently updated my iPhone 4 to iOS 4.3.1. Everything seemed to go fine. However, after I sent my next text message the phone quickly showed the restart screen and then all my old messages were deleted. Thinking it was a fluke I restored to before the update. Everything (except the messages I had sent between the update and restore) showed up again. However, again, as soon as I sent another text, my phone restarted and all the old messages were removed. I'd like to keep my old SMSs on my phone and still be able to send/receive new ones.

Any ideas?
Open up "Settings" then tap on "General" and scroll down to the last option "Reset". Tap the third option "Reset Network Settings". This will take a few seconds and then your phone will restart. 

BE ADVISED Doing this will deleted your saved wireless network passwords and wireless network history so you will have to reenter these passwords to reconnect to wireless networks. This option does not delete any of your personal data off your phone.