There is, but it takes patience, time, tolerance and possibly being able to do without any kind of answer (answering device included). Calls continue to numbers known for having an answer. After enough times of never getting anything from the numbers they call, they do get tired of calling them and move along. It takes time to cut back on the number of calls you get. If you're unable to do without an answering device, a call blocker or app may be of use. Make sure unknown numbers get no kind of answer, though, if you're able.