How to block a no caller ID?
iPhone 5, iOS 10
You can automatically reject and send all calls from callers not in your contacts, email, messages, etc. to voice mail without ringing in Settings>Phone>Silence unknown callers.
This includes calls with no caller ID.
That is a feature of iOS 13.
If your signature is accurate and you do actually have a device running iOS 10, then you can't do it.
Check the App Store
There is nothing like what you mentioned.........If the opposite
was true I would not be asking that question
" Settings>Phone>Silence unknown callers."
The option is not found on your device because it is too old and out of date.
You have a 5 running iOS 10 and you need at least 12 for that feature.
They have iPhone on IOS 10, this only works on IOS 13
How to block a no caller ID? Please only answers on that topic......