Most of those solicitation calls are for fraudulent charities anyway. A while back, one of the local sheriff's offices sued one for pretending they were calling from them.
AND there are a ton of mostly disease-related fake telemarketing charities run by this one family that's gotten filthy rich tricking people into thinking they were donating to kids with cancer and stuff like that.
The Tampa Bay Times has a whole series on it:
America's Worst Charities, a Tampa Bay Times, CIR and CNN Investigation | Tampa Bay Times
Never give money to organizations that make unsolicited telemarketing calls. They're 99% fraud, and the 1% that aren't are still spending their resources on telemarketing.