No signal or 'No Service'? How to tell if it's your SIM, your network, or your phone

This sequence isolates the cause fast. The key tests are swapping the SIM and checking whether others on the same network are affected.

• Toggle Airplane mode on and off, then restart the phone
• Ask someone near you on the same carrier — if they've lost service too, it's the network
• Power off, reseat the SIM (check for damage/dirt), power back on
• Put your SIM in another phone — if it also has no service, the SIM or account is the issue
• Put a different, working SIM in your phone — if that one works, your original SIM/account was the problem; if it doesn't, the phone is

If the SIM checks out, try the software side before suspecting hardware:

• Install any carrier-settings or system update
• Reset network settings (this clears corrupted network config)
• Switch network selection to Automatic, or manually pick your carrier
• Check for a local outage or a coverage gap where you are

Point the finger at the phone if:

• A known-good SIM still shows No Service in your phone
• Signal dropped right after a drop, a screen repair, or water exposure
• Signal is permanently weak everywhere, even in strong-coverage areas
• It only works on Wi-Fi calling but never on the mobile network

When it's hardware, the cause is usually the antenna, antenna flex, or the network/baseband section of the logic board — chip-level work, not a simple swap. iTweak does board-level repair on ESD-protected benches and diagnoses the exact fault before quoting, for Apple and Android. If we misdiagnose it, you don't pay, and you get a digital invoice with warranty details on the repair.