Thanks for visiting Apple Support Communities.
It sounds like you've tried a lot of good troubleshooting steps. The troubleshooting article below recommends contacting your carrier if the you still see a "no service" message after trying all the troubleshooting steps.
iPhone: Troubleshooting No Service
- Try turning iPhone off and then on again.
- Remove the SIM card and verify that it is a valid, carrier-manufactured SIM. Also verify that it is not damaged, worn, or modified. Then reinsert it.
- Check for a carrier settings update. Tap Settings > General > About while connected to a Wi-Fi network. If an update is available, a prompt should appear soon. If Wi-Fi is not available, connect your device to iTunes.
- Update your iPhone to the latest version of iOS.
- Restore the iPhone.
If you're still experiencing No Service issues, contact your carrier to check for any network or account issues that could cause this issue.
All the best,