I use a software called phonetray - not it is not free, but it works...I simply block the number and add a voice reply like "Not accepting calls" or "Not accepting Telemarking calls" among several options. When this number come in, it rings once and that it! I can block up to 1,000 numbers, and accept the same number by adding them to a white list and have the option of adding a name or some other note to let me know who is calling...it displays on the PC screen, announces the caller name and number...nice.....
I did not answer since it was noted as "unavailable" and they left a very long messages about life insurance. Robo call that will be reported to the useless do not call registry.
Calls numerous times a week. Sometimes the caller speaks sometimes not no matter how many times I say "hello." If the caller speaks and I don't recognize I hang up immediately.