Mystery Solved. These calls are NOT coming from The Heritage Foundation. They almost certainly originate from telemarketer The Heritage COMPANY. http://www.theheritagecompany.com/
Many times these organizations farm out their fundraising. These fundraising organizations do not care how much bad will they make for their client as long as they get a cut of the donations.
Even worse, these organizations claim to be collecting in behalf of some worthy cause that does not know about it.
Steve makes an excellent point. The Heritage Foundation is an upstanding organization. My bet says it's an opposing group trying to irritate persons who might, who do, or who have supported Heritage.
Consider Kim's note. When Kim answered their call, they didn't speak. If a legitimate caller is soliciting you, they are not going to hang up when you answer your 'phone!
I've recently begin getting calls from this number 323-330-1426. They don't leave message and call morning and night. Very annoying. Ironically my husband recently got a package from Heritage Foundation. Haven't asked him but wouldn't be surprised if he donated.