I don't think the carriers have final say unless the device manufacturers want them to. For example, people seem to be using the P800 on various US cellular networks even though it isn't approved or sold by any of them. The only problem is that you'll never see a P800 bundled with service; you have to buy it separately. This is a model that worked fine for years in Europe. But Danger has chosen the proverbial "deal with the Devil" instead.