Got a call. Didn't recognize the number so I didn't answer

My mother got a scam call from the number today.

numerous calls from this number in the past week and no voice mail left.  I don't answer calls especially out-of-state if I don't know who it is.  Too many scams going on

It rings once and that's it. I've got it at odd times during the day maybe 3 times in the last week. I searched and on MrNumber.com  found this:

-323-612-0121 is not a valid number. If you are sure that you got a phone call from a number beginning with this prefix, the caller may have 'spoofed' caller ID.
Mr. Number Report Card

90% Current Spam Score *
54 Lookups **
1 Spam Reports **
* Suspicious numbers have high scores
** During the last 30 days

My cellphone reports that a call came in from this number.  Number2Name.com reports that there is no such number.  (There is a 323-611, but no 323-612.  So it is a faked caller ID.