Call at 10:30 am. I could hear voices in the background, but nobody spoke to me. Sounds like a boiler room, where calls are autodialed and the scammer decided to take a break.
I called them back and got a voicemail service saying that it's "MDS Communications - a telephone marketing service for national fundraising. Basically for non-profits and political campaigns. Option to get on their do-not-call registry, but they mention that since they're not-profit, they don't apply to the national do not call registry.