Your question is often asked on 800 notes. Short answer: No idea. Longer answer: Due to caller ID spoofing (faking) your caller could be anyone anywhere in the world. Criminals use computers, high speed internet, VOIP, & a few dollars in software. Best policy is to never call back unknown numbers, and never assume on an incoming call that the caller is who they say they are.
I have a French phone number and I am not American.
Missed two calls from this number on Thursday and Friday. On Friday I also get information through email that someone has requested personal information about me through an application I've got installed on my phone called "Truecaller" which is a blocking app.
I didn't even know you could ask information about someone this way.
On Sunday the caller calls again, this time I answer and before the caller hangs up I only here some ambient background noise.