Back to the screen that asks for SIM insertion and iTunes connection on background. Is it?
Yes assuming you haven't upgraded the firmware or OS past the factory state.
Whether or not you can revert to factory levels, here is how to get it ready for activation:
Remove the SIM and power off the device. Then plug it into iTunes while off and holding the home button all the while until you see the connect to iTunes icon. This is recovery mode but the device still has user data on it.
Your computer then can wipe all content and re-install any OS that is the same or newer than the OS that is currently on the device. You can load iTunes with older images than is current but just not older than is currently on the phone.
You can't go backwards in terms of undoing an update on the phone without modifying/jailbreaking the device - even then it's not a given and rarely successful in reverting back to factory OS or firmware.
Once the restore is complete disconnect the phone from the computer before replacing the SIM card.