I get lots of this kind of call and a bunch of others that are "would you like to donate to help children with cancer at christmas" kinds of calls.
Some of those calls are legitimate--sort of. Most telephone solicitations for nonprfits (which btw are not subject to the do not call regulations nor are political parties) are done not by the charity itself, but by professional fundraising companies that take anywhere from 40% to 60% or more of the "contribution" and pass what is left on to the charity sometimes. The charities hire these companies because it usually does not cost them anything and they figure that any money they get is better than nothing. Nothing is what they figure they would get if there were no calls. Charities often agree to a "script" in which the professional caller tells you that all of your contribution is going to the charity, even though the charity and the caller know that is a lie. The charities feel that if you knew how little of your money was actually going to them,you would not contribute and they would be back to nothing.
http://www.npr.org/2012/09/12/160997044/when-telemarketers-pocket-money-meant-for-charity Of course many, many of these calls are from scam charities. In Washington State, all a charity has to do is register with the secretary of state and give a small portion of what they collect to the people they claim to be helping, and they are perfectly legal. Some of these registered charities collect hundreds of thousands of dollars, use a few tens of thousands to do something "charitable" and pay their CEO and his family the rest. Perfectly legal.
If you want to give to a charity, write a check to the charity. If you do that 100% of the money will get to the charity. A much smaller percentage will actually get to the end recipient in most cases however, since most charities pay their executives, advertising agencies etc. a good chunk of their intake. Never give money to a telephone solicitation.