If you receive calls from (800) 837-4966,and then they hang up you can call or write them at: Frontier Communication, 119 North Commercial,St., Bellingham, Wa 98225
Headquarter's phones 360-676-1100 or 360-738-8506
They are a long distance phone service company.
I went this route to get them to stop calling me and leaving messages on my machine like, "Hello. Hello, Hello, I am with Chase, then hang up".