I did this a while back, and was informed it was a “spoofed” number. That was a new one on me. And the guy with strong foreign accent, was very threatening, and wanted me to verify my SS number. I didn’t.
I have a friend who did a “jailbreak” on her IPhone and was able to obtain an application from Cydia which spoofs whoever she dialed. She dialed me and it rang but looked like a different number.