I requested a code yesterday but never got the call when I hit the call request button. I got the call at 1:31 am this morning and it was silent for 4 seconds then said "Goodbye" and I'm really freaked out now!
It's the number that FB uses to verify anything that requires you to prove you're you within Facebook. It only works at the moment they call. If you call back, you won't reach anyone. It's automated. If you're getting calls at this number, A) someone is trying to access your FB account or buy advertising on Facebook through your account. B) You recently got a new number, and someone still has this number associated with their FB account.
Automated call from Facebook to confirm new browser sign-in. Can happen if you clear cookies from your computer, and try to sign in on FB. It's calling to confirm your identity.
when you try to log on from an unknown browser, facebook will text you a code or call you with a code for you to enter as verification. no threat here guys. I just experienced this myself and i was like REJECT- I dont know anyone in CA- but then I realized I had accidentally clicked the "call for code" button instead of "text me a code" button when I was logging in on a public computer. Hope this puts your mind at ease :)