Experts revealed that there is a hidden hack in the iPhone settings that can be activated to block annoying calls that come with “No Caller ID”, and the Silence Unknown Callers feature can simply be activated, but the disadvantage is that it will block Also most of the numbers are not already added to your contacts.
The iPhone 5S, iPhone 6 and 6 Plus or earlier models do not support this feature, and Apple's Silence Unknown Callers feature came in an update to iOS 13 for iPhone in 2019.
So, if you really feel that you need the ability to block unknown calls, you might want to consider updating your phone. Some third-party call blocking apps for iPhone, such as the Mr. Number, iOS 13 or later.
But, if your iPhone is up to date and you're ready to get rid of unwanted callers, here's what you should do.
Go to the Settings app on your iPhone's home screen.
Once you're in Settings, scroll down to the green "iPhone Apple" app settings - tap on it.
Towards the bottom of the menu on this screen for your iPhone's Settings, you should see the "Silence Unknown Callers" option near the bottom. Click that to enter the next menu.
Now all that is left to do is simply toggle the switch to block No Caller ID calls.
But there are some caveats:
First, this feature will silence these mysterious calls but not block them completely. These numbers will still be able to leave you voicemails, which is something you might be grateful for if someone in your family is in trouble and reaches out to you from a strange new phone.
And if you really need to block these calls, your best options are to contact your phone service provider directly or download a third-party app like Mr. Number that will block callers for you.
Users may appreciate that the iPhone's operating system takes some liberties in muting audio. For example, iOS sometimes allows unknown callers if their number is associated with a recent outgoing call or if it's a number from an email or text message found by Siri Suggestions.
The most advanced update comes thanks to Apple's Neural Engine — iOS17 will be able to directly transcribe incoming voicemail messages, a feature called Live Voicemail, allowing users to judge whether to answer or ignore a call based on the incoming message.