It would be best to simply not answer when these lowlifes call. as it has been widely reported, the callers are drug addicts, recruited at Narcotics Anonymous meeting, for the purpose of scamming people. It is evidenced by their language they are of a lower class than civilized people, so don't let them bother you. They are rarely seen, except in the lowest class of neighborhoods, but can easily be recognized by their grotesque drug-induced features.
This solicitor only lets the phone rangs once, does not say anything. When you call back
you are asked if you want to be removed, verify the number called and press one to be removed.