I got a call from this number. When I tried to call back it wouldnt even ring on the other end

Some one is calling me from this number. How I can stop them?

someone from this number constantly calls my phone but says nothing and you can't call them back

This number keeps calling me. But by the time i call the number it says the number is invalid or no longer in service. But they have been calling me for about a week or so. How can they call me for so long if the number is disconnected?