Replace PIN with your carrier’s barring password (default is often 0000 or 1234 ; contact your carrier if unknown).
Some carriers offer a feature to block all incoming calls using a USSD code. However, this code may vary depending on your carrier and country. Here are a few examples: ussd code to block all incoming calls android
Unlike your lock screen PIN, the barring password is a 4-digit code set by your mobile network operator (Carrier). Replace PIN with your carrier’s barring password (default