I use Skype-In / Skype-Out (they may have changed what they call them now!) which I think does much the same thing.
For example, when SWMBO was in Australia for a month I set up a Brisbane Skype-In number so that she could make a local call from there and the phone would ring here.
Likewise, when I ran my own business I set up an 0207 number so that I could have a central London appearance. As for Skype-Out, I have a geographical number which appears as the Caller ID when I make outgoing calls.
I think they are much of a muchness but you DO need a fast broadband connection - I have 120MBS from Virgin so I am fine.
Also, I have a GREAT dual handset which plugs into my landline and my router and gives me DECT handsfree for both Skype and TDM calls.
David