You should check out google voice, it's free for calls in the US and if you already have a cell, it can forward calls to your cell, and most major cell plans can already be integrated to your cell.
[youtube]https://www.youtube.com/embed/UFRJ3QYC0vY#aid=P-ZZFjrkd9A[/youtube]
I have heard good things about it from others. I may even try it out now as I have given up my landline for awhile.