Q: Block calls without ID

Nuno Azeredo wrote:

 

how I can block calls without ID?

Block phone numbers and contacts or filter messages on your iPhone, iPad or iPod Touch - Apple Support

There is no method through the iPhone software to block calls from those without caller ID. Perhaps your carrier might have a means?

For now, you can utilize Do Not Disturb. Use Do Not Disturb on your iPhone, iPad, or iPod touch - Apple Support

In Settings>Do Not Disturb, set the feature to Manual and Allow Calls From "All Contacts."

Enable Silence in the bottom of DND Settings to Always. This will only apply to attempts made from the calls and text messages of those that are not in your Contacts List at present. You will still be able to view your recent call history or voicemail to identify if the call was from someone you would preference to have in your Contacts. Add them and they will not go ignored again.

While the Do Not Disturb function would do a good job of preventing notification from callers other than those in the iPhone Favorite list, it also prevents all other notifications, such as SMS, iMessage, Mail, etc. With Do Not Disturb on, the only thing that will get through are calls from your Favorites.

Otherwise, your statement to contact the cellular carrier about any blocking features is spot on.