If you're waiting for an important call, it's unlikely going to come from 'no caller id', so time wasted by a nuisance call can be frustrating — we can teach you how to block 'no caller id' on iPhone without an issue.
However, iPhone isn't perfect with its Silence Unknown Callers feature — this not only blocks 'no caller id' calls but any number that isn't in your contacts, even if it has a 'caller id'.
With that caveat in mind, here's how to block 'no caller id' on iPhone.
How to block 'no caller id' on iPhone
Step 1) Navigate to your Settings app on your iPhone.
Step 2) Scroll down to Phone — tap it.
Step 3) In this screen you'll find the Silence Unknown Callers tab near the bottom.
Step 4) Now you can actually flip the switch to block 'no caller id' calls.
That's pretty much all there is to it. Additionally, if there are any calls that don't meet the aforementioned requirements, sometimes the iPhone will let the call through if it's a number tied to a recent outgoing call or if its in Siri Suggestions.
If your iPhone is out of date, consider getting a new phone that features the upcoming iOS 17, which can listen to incoming calls for you, and you can decide whether or not they're urgent.