This only started happening recently but just want to check on here if anyone knows what is causing this before I make an appointment at the Apple Store. When my iPhone 4 has been turned off and I turn it back on it takes a while to find signal, At the least it's about 10 minutes before it stops saying Searching... in the top left corner. During that time I can't ring anyone or text etc but then when it does find signal it's fine. It's not the sim card or carrier as I have tried it with both O2 & Three sim cards and exactly the same thing happens. I have also tried a restore and set up as new and that didn't fix anything.