samsung galaxy tab's ability of making phone calls is real, and it is one of selling points, but there are 2 bad news you have to know, the phone calls are not so easy to make actually.
1. this mod works only for the T-Mobile version of the Galaxy Tab
2. the modifying itself is not the easiest you have done in your life. That said, this is only the beginning and we're sure that subscribers of the other carriers will get this mod very soon, while the hacking process that allows making and receiving phone calls will be facilitated.
It is really good for those who want to have one, but i think ther's no point that you spend a lot of money on a gadget that can't make simple phone calls...