Q: how can i block unknown callers

NNot if there is no number available to block. If comes through and shows on screen as "Unknown" there is no number to block.

To quote an old twilight zone "you think about that now". Despite there being no number, the iPhone lock screen knows. It offers two options decline answer for no caller id or unknown. If a call has number offers other options like reminders response etc. WHen ios knows there is no it doesn't offer reminder, response etc. ios does know the difference.

That information is based no only on Caller ID info, but in info that is contained in your Contacts. Again, when there is no Caller ID feed, there is no way to block the number. I understand your logic, and it does somewhat make sense, however as far as the phone is concerned, the only option to block something is to enter a number for the phone to translate. The ability at this time does not exist to enter a block to numbers that do not come in with a Caller ID feed.

You can make a suggestion to Apple after explaining your idea HERE, and click on the appropriate subject.

I have created a contact as you proposed, and blocked it...we'll see. like you I won't know if it works...or will I? :–)

Doesnt work...already tried it...

Using manual Do Not Disturb to only allow calls from people in your contacts list is not a good option either.

When you turn no Do Not Disturb all text messages are blocked when the phone is locked regardless of the setting to allow phone calls from people in the Contact List.

So if your phone is locked and DND is on, you will get voice calls from Contacts but no text message alerts.

In fact all notifications will be silenced so if you have Reminders or score alerts (via ESPN app or Bleacher Report) you won't get those either if the phone is locked and DND is on.

This idea didn't work.

Simply copy UNKNOWN and paste it into the blocked caller list--worked for me.  No number entry required, just paste it.

Trap call reviews are abysmal. It does not do what it implies.. You want the "unknown" , etc not to even get through to your phone. and forget blocked calls they show up again. We are registered on the "Do not Call" registry. There is got to be a better way to keep these scam/spam calls from coming through. js

Actually, cell phone carriers could offer a solution but they obstinately refuse to do so. Land line services offer a feature called "anonymous call rejection" meaning any call without valid caller ID in the clear is blocked at the landline switches. There is absolutely no technical reason that feature cannot be offerred to cellular services, but in most countries, carriers have steadfastly refused to do so.  The service is usually free with landlines. Some carriers (e.g. Verizon) ooffer a service for cell phones, but they charge monthly for it ("my usage controls" or some such add on service with Verizon?).

i seem to remember at least one U.S. Congressional attempt to introduce a bill requiring cell phone carriers to offer anonymous call rejection at no charge to cell phone services, but typical of our dysfunctional government, the idea went nowhere.

one time at work I was complaining that I keep getting marketing calls from the same area code in WA. My friend and cubicle neighbor at work suggested I go to "recents' and click the  letter i in the circle and block that number so it doesn't call again.  It happened a few times still with the WA area code (I guess different extensions from the same office) but the calls stopped from WA.

this may not be a good idea if you are job searching.  You  may receive a call from a headhunter that you will never know about.

Completely agree.  There is no technical reason this can't be done.  They just won't.  Not even offering as paid service.  Is ridiculous.  They already know enough about the call to know to call it "Unknown", so that that point just don't let it through.  Let the governmental powers that be have to put up with twice daily Unknown calls and see how fast action is taken. 

TrapCall allows me to double-tap the sleep button to redirect to them to play some recording, but i STILL get the call in the first place.  Their service will unhide the number, if it is even non-spoofed, legit number, but that doesn't help because the incoming call is still hidden and iPhone can't block it.  I can only block numbers that are shown.  The only thing then that TrapCall does for me then after that is play some 'not in service' type recording and then I have to hope that eventually the auto-dialer program at the scumbags' computer will take the hint and give up.  If their dialing bot software doesn't care about that, then I will continue to get the calls. 

I can set iPhone to Do Not Disturb 24/7 and only allow incoming from my contacts, but it STILL shows up in my call history as a missed "Unknown" call.  Ok, so it doesn't ring my phone, that's nice, but I don't even want to see it.  Is so aggravating.  And they have started up again recently.  Problem with the 24/7 DND and only allowing contacts is that I can miss calls that I actually want, like say from random UPS driver, or the lawn guy, or A/C guy's cell phone, etc.

I really do not get why there isn't a better solution out there for this.  I have had all our numbers on national and state do not call registries but this particular verminous miscreant doesn't care.

I could block "Unknown Callers" on my Samsung Galaxy.

Ahhhhh, but then you have a host of other problems....