My wife just received the same call from 256-000-0000. Woman on the other end said "Oops, wrong number" and then hung up.
We have Internet phone service through Vonage, possibly grouped in with available cell phone numbers (numbers in the local area code that don't have to be physically located there).
I think this is a recorded voice with a computer on the other end collecting valid (answered) phone numbers for telemarketers.
I filed a complaint with the National Do Not Call Registry:
https://complaints.donotcall.gov/complaint/complaintcheck.aspx
I got the same weird call, I answered and a young lady said, Oops wrong number and hung up.. I called the number back and of course, It gives you the wrong number dialed message..
Ever since I got the call last night.. I have gotten 3 telemarking calls from 702 and 761 area codes.. never got telemarketing calls until, this lady called and said oops wrong number and hung up yesterday afternoon... Nice...