I've NEVER signed up for facebook and I've got several of these calls. Maybe spoofing but facebook , in this case, is not calling me. I've had my number for over 6 years so they are NOT calling to confirm my identity. Can only guess it's someone trying to make a buck from someone else.
This was an automated call from Facebook, calling me to verify a group that I administer. I requested this call to get a 4-digit code number to enter online. Strangely, I forgot that and when I saw the number on my caller ID, I used a "fake caller ID" app to call it back. But rather than ringing through to the 650 number it somehow forwarded the call to 707-401-1004, which according to Google is a number tied to a reputed scammer. (https://www.callercenter.com/707-401-1004.html) So who knows.