iOS 11 Ringtone for No Caller ID Is there any way (even a brute-force workaround) to assign a unique ringtone to "No Caller ID"?    

Manually assigning a ringtone to all contacts and setting the default ringtone to something different is not an acceptable solution to the problem, because both unknown callers and No Caller ID callers will use the default ringtone.  I would like a ringtone that's unique specifically for No Caller ID.  Thanks!
The following is an old trick, I don't know if it's still working :


Create a new contact called something like Non-Caller or No-Caller
Enter 000-000-0000 for the phone number.
Assign your unique ringtone or/and block it


src: https://discussions.apple.com/thread/6040239

Personally, I'm using the Truecaller app:

https://itunes.apple.com/us/app/truecaller/id448142450?mt=8