I have an IPhone 4s and for some reason during the last few hours it tells me there is no service. I am with Rogers and when I am hooked upto wifi I can Ichat and go on apps, but I cannot make calls or recieve or send any texts.
This has never happened before, I have tried turning it off, etc..
Once in a rare while I get the same problem on a 4S. I've never touched the SIM card, but I normally power the phone off and back on, then wait patiently for it to reconnect. You can also go into your settings, then disable/enable the carrier and that sometimes works as well. I don't know if the problem is with the phone or the signal, but I suspect it might be the phone.