Well here's a flip on Vonage’s tried and true business model (that mind you has landed them in debt to the tune of over 400 million), Vonage offers your unlimited calling (to the US, Canada & now Europe!!!) with a free phone adapter, Skype in combination with Mplat are offering you free calls to the US & Canada (well at least until the end of 2006 and only if you are within the continental US), if you're willing to plunk down $50 for the Jumper S100.
The Jumper S100 allows users to use a standard telephone to make telephone calls on the PSTN network, via Skype. It supports voicemail, voice recording (hmmm) three way conferencing (which you can use to join Skype & standard telephone calls) and call forwarding and these features are facilitated by the use of add-on software. Unfortunately the software that allows Jumper to have all these features is only available on the Windows platform.
[Take from Engadget ]