Hi guys
Looking at this lengthy forum I've too had this problem after replacing with a new battery for my 4s!
I've tried everything even linking it to iTunes but no joy. I've been almost 5 days without calling signal only wifi.
I've been told by my network carrier that a faulty sim could be to be blamed! I'm going to try this otherwise IT will be a complete reset back to when I bought it again.
I think Apple must do something which must link up when things are changed etc. As now my silent switch is not working..... Spooky!!