I get solicitation calls all the time on my phone. When I try to call the number back that shows on my screen, I get, "this number has been disconnected or is no longer in service". So they aren't even using a number I can trace to report them. But I do go to my provider's (Verizon) website, access my own account and block the numbers they have called me from. It then takes them a few more days to find me again..
I am getting up to ten to fifteen calls a day on my cell from these solicitors. I may change my cell number but I have had it for 13+ years and it is my only home phone number. oh well.. change is good they say!