Hello there, AMaster1.
The following Knowledge Base article addresses the very error message you are describing and provides some great steps for troubleshooting:
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 a known-good Wi-Fi network if you're unable to activate using a cellular data connection.
- Try connecting to iTunes if you're unable to activate using Wi-Fi.
- Restore the iPhone.
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.
Thanks for reaching out to Apple Support Communities.