How do I set up a digital voicemail system that could be converted to mp3's?

I’m trying to collect a wide berth of voicemail audio samples for a multimedia project, but my limited technology experience is proving to be a hurdle.

My goal is to set up a phone line or voicemail system where folks could record or forward their voice messages and I would have the ability to convert them to mp3s.

Ideally, the voicemail system would function as follows:
– I would have a phone number that I could publicly distribute via social networks, flyers, word of mouth, etc. (Without being tied to my existing cell phone service or me as an individual)
– When folks call or forward their messages they would hear a quick disclaimer regarding submission anonymity.
– At my leisure I would be able listen to the messages left to delete the creepy ones, and convert the interesting ones to mp3s.

Is this possible? If so, dear internet, please tell me how.