I brought a Iphone 4s on ebay they said it hs no signal and the image showsed it was connected to the carrier but no signal bars. when i got it is says no service why. it is a o2 sim same as what they had.
iPhone 4S
Well your first mistake was buying a phone on ebay. It was probably illegally unlocked for o2 and if you updated the software then it takes the hack off and reverts to being locked to whatever carrier it was originally locked to. Go to Settings>General>About and tell me what it says for Network and Carrier.
Network Not Available
Carrier O2 14.0
Why is my iphone 4s saying no service all the time?
