I got this call too. I never answer unknown callers. If they leave no message = spam, and I block them from my phone.
I cannot back up Mike's claim above, that this is a legit charity: Charity Navigator has no listing for "Donor Network America," and there is no website for that organization. A Google search gets a total of 7 (useless) hits, one of which is this page.
Multiple calls from this number. Caller ID says "NARAL"...But NARAL headquarters are in Washington, DC, so not sure why a call is coming from Southern California. No message, just repeated calls.