Q: How do I restore after getting a message Activation Error?

I bought a used Iphone 4s and dont now much about it. Have not had it activated by a carrier yet and was using the wifi

now I get an error that says; Activation Error. Does anyone know what this might be. I see the versions need to be updated to 7.0

or the phone can be bricked. I do not know what version it had updated to as I bought it over 8 mo. ago. Thanks for any

input you might have. Lanny

ps; When I hook it up to my laptop Itunes it says it needs to be restored before any songs can be added.