This is a 2 ring hangup probably from some computer scammer testing to see if there are live numbers at the end of the line, so then they can sell them to some unsuspecting telemarketer, as good numbers. I get calls to my 704 area code cell phone line this, from 704-445-3612, then in the morning, 704-445-3611, then 704-445-3608, 704-445-3607 on the 13th, another call from 704-445-3608 on the 10th that I forgot to mark SPAM