First of all, you all must be aware that I am not tech-savy. Anyways, I updated my own Galaxy S2 and soon my mothers to Jelly Bean. Ever since, this would occur randomly throughout the day. At one point, the Galaxy s2 would not be able to receive/send any texts despite having signal or receive/send calls, or even use the 4g network. Wifi is still available to use though. It gets fixed by restarting the phone every time, and it wouldn't occur for awhile. Although this solution does get really annoying as sometimes you won't know you receive a text until you notice it's having the problem again and needs to restart. I'm having a feeling that this relates to the jelly bean update because it never occurred with ICS. Much help is appreciated!