all phones can connect to multiple networks, so if you go abroad you can roam on an alternative network
it is similar to that for you as well, although there is no point in connecting to an alternative network, as calls etc will not be included
also, in future please dont post threads with such a non-descriptive title
Aren't those cell phone providers (companies) that sell the iPhone?
yes, but they are also all the operators that operate in the UK