Hey There. I have had a similar thing since last year. Its a box that hooks upto the net and you just put the regular phone into the box and then it connects with skype. It was terrible, sounded like an indian call centre as sometimes the people sounded distant.
I have heard the newer ones are streaming at 128kbs so that should be perfect, but not so sure.
Skype are offering calls on my 3Phone now too, might give that a try