They do, and the form to port your number, if number portability is
available, is on the provider page along with info on how this works.
I personally think Viatalk is a better deal, which is why I went with
them. Besides, no problems here with them. Anyway, why not have a
look at the page? Read all the FAQ's and support. I'm sure all your
questions are already answered in more appropriate places if you'll
care to do a bit of legwork.