After the release of iOS 14.7.1 there are several reports that device shows ‘No service’ message when it definitely should have service.
Apple currently recommends following support article for potential resolutions.
Reference: iOS 14.7.1 users complain about ‘No service’ bug after updating their iPhones
Recommendations
Developer:
Beware of potential issue.QA engineer:
Beware of potential issue.PM/DM:
Communicate risks of potential issue to stakeholders.