I have been using Skype and very impressed with the technology.
My developer and I use skype to keep in contact as we develop t3report.com
He just sent me this link to a Skype Answering Machine....looks pretty slick. haven't tested it yet... it's free (donate-ware)
http://www.freewebs.com/skypeansweringmachine/index.htm
Fight the DND!