Start with reversible checks
Airplane mode, a restart, carrier status and testing outdoors are safer first steps than deleting an eSIM or resetting every network setting.
Location patterns reveal the cause
A problem limited to one building points toward local coverage or shielding. Failure everywhere after a SIM change points more strongly toward activation or device configuration.
Emergency calling is different
SOS availability does not prove normal carrier service. For an emergency, follow the iPhone emergency interface and local emergency-service guidance rather than continuing troubleshooting.
Frequently asked questions
Why does my iPhone say SOS Only?
It generally means normal service from your carrier is unavailable while an emergency network may still be reachable. Coverage, outage, SIM and account issues can all cause it.
Should I reset network settings first?
Usually not. Test airplane mode, restart, another location and carrier status first because a reset removes saved network settings.
Can a damaged SIM cause No Service?
Yes. Activation, provisioning, a damaged physical SIM or an incorrectly configured eSIM can prevent registration.