Welcome to the Apple Support Communities. if you are having issues with activation, the following article will guide you through troubleshooting the issue.
Perform the following steps if you receive one of the messages above:
- Restart the iPhone.
- Try another means of reaching the activation server and attempt to activate.
- Try connecting to Wi-Fi if you're unable to activate using a cellular data connection.
- Try connecting to iTunes if you're unable to activate using Wi-Fi.
If you receive an alert message when you attempt to activate your iPhone, try to place the iPhone in recovery mode and perform a restore. If you're still unable to complete the setup assistant due to an activation error, contact Apple for assistance.