iPhone doesn't pick up wifi automatically
Sometimes it does, sometimes it doesn't. Often my iPhone doesn't pick up wifi when I come into a wi-fi zone and stays on GPRS until I go into setting, wifi and then it picks up the network. Sometimes it does it automatically but it's annoying when it doesn't. It sometimes does the same with network signal if you go into a 'No Service' area and then come out of it it often takes a long time to pick up the network signal again. What could be wrong?
iOS 5, MMS, iPhone 4S