Oppo
Block Unknown Callers Automatically auf Oppo
Unknown callers get through because ColorOS treats every number outside your saved contacts as a normal call unless you turn on the filter.
The block only compares the incoming number against your contact list, not against a spam database. That means calls from delivery services, doctors, or new business contacts get rejected too, not just nuisance calls.
To turn it on, open Phone ➔ Open the Menu ➔ Tap on Settings ➔ Tap on Blocked numbers ➔ Enable or disable Unknown. Once enabled, any call from a number not stored as a contact is rejected automatically.
ColorOS builds in one exception: if the same unknown number calls again within three minutes, the second attempt rings through. This stops you from missing an urgent follow-up call from the same person.
Turn the option off if you regularly expect calls from new numbers, for example while selling items online or during a job search. A manual block list for specific numbers works better in that situation than a blanket filter.
Blocked calls do not ring and are kept out of your normal missed-calls list. Check the blocked numbers log if you suspect a call was rejected by mistake.