Samsung
Enable or Disable SIM Card Lock auf Samsung
Samsung phones ask for a SIM PIN after every restart because carriers activate SIM card lock by default. This setting is separate from your screen lock or device PIN, and it only protects the SIM card itself, not the phone.
Without SIM card lock enabled, anyone who takes the SIM card out and puts it into another phone can use it right away, including making calls on your account. With SIM card lock active, the PIN prompt appears every time the SIM initializes, whether that is after a restart or after moving the SIM to a different device.
To change this behavior, open Tap on Settings ➔ Tap on Biometrics and security ➔ Tap on Other security settings ➔ Tap on Set up SIM card lock. On dual SIM devices, pick the Choose a SIM card (Dual SIM) you want to change first. Then use Enable or disable Lock SIM card to switch the setting, and confirm with Enter the current PIN and tap OK.
Disabling SIM card lock only removes the PIN prompt during restarts. It does not delete or reset the PIN itself, so keep it noted somewhere. If you enter the wrong PIN too many times, the SIM locks completely and needs a PUK code from your carrier, which is a separate step from this menu.