You could do that... the benefit of Rebtel's service though (I work for them) is that, once the local number's been generated and stored to your phone, you can call your friend from your mobile, whenever and whereever you want. No need for a computer. Also, Rebtel calls can be free if you and your friend have inclusive minutes on your mobile phone contract. You just need to make a Smart Call (where your friend calls you back while you stay on the line), and you'll be talking internationally on your mobile for free.