I understand where you're coming from. If someone does want to donate to a charity, make sure you do it as anonymously as possible! Never provide any kind of legitimate contact information or they will hound you like a swarm of mosquitoes.
I ran into this problem with Habitat for Humanity. Before Caller ID and when answering machines recorded on tape, a caller would call every day at about the same time and hang up at a point where my answering machine would run the tape to the end with nothing on it, preventing any legitimate callers from leaving a message. One day I was home from work early and at the time of the mystery calls the phone rang - it was Habitat for Humanity who I had donated to just a couple of weeks earlier. I made it clear that their calls were unwelcome, and lo and behold the "mystery calls" stopped.
NEVER give any charity your contact information! They will hound you day in and day out!
Called just a bit ago. They hung up on the third ring. Don't believe we have ever rec'd a call from that number before. I see from other posts that it might be from an "organization" called American Institute for Cancer Research. You can check this group out for yourself at http://www.charitynavigator.org/index.cfm?bay=search.summary&orgid=3264 and see that they appear to be questionable to say the least.