OnePlus
Block Unidentified Callers Automatically auf OnePlus
Calls without a caller ID usually come from numbers that are suppressed, spoofed, or simply not registered with a carrier database. OnePlus phones running OxygenOS include a dedicated filter for exactly this case, separate from the general blocklist for known numbers.
The setting lives inside the call-blocking section of the Phone app. Once enabled, any call arriving without an identifiable number gets rejected automatically, without adding a single number to your block list manually.
Where to find the setting
Open Open the Phone app ➔ Open the menu ➔ Open the Settings ➔ Tap on Blocked numbers ➔ Enable or disable Unknown (Block calls from unidentified callers).
Turning this on blocks every call that arrives without caller ID information. Turning it off lets those calls through again, which is useful if you rely on services or contacts that regularly call from withheld numbers.
This filter works independently from blocking specific numbers. If a known contact occasionally calls without caller ID, for example while roaming, this toggle would block them too. In that case, blocking individual spam numbers by hand is the better option instead of the blanket filter.