No caller ID; no message. I called the number back. A recorded message says that it is from SD&A which is a national call center for established nonprofit organizations. A comment on said that the number belongs to Sierra Club. I belong to several nonprofits, so it could be SC or another charitable org. You can have your number removed from the call list by leaving your number at the end of the recorded message.
 Apr 10th, 2017
No message. I don't answer unless I know who it is and this number just keeps calling. Annoying.
 Sep 10th, 2014
Calls and doesn't leave a message.
 Jun 29th, 2014
This number has called my cell phone repeatedly (14x) over the past two months. They NEVER leave a message. I suspect some "contest" sold my number to them. Unfortunately, I can't block it, but I never answer. It is very annoying!
 Sep 13th, 2010