For example, to set up my service in Australia, I bought a SIM card in a little packet at a corner store for A$40. The SIM card was from a specific wireless provider (Telstra, in this instance), but it was sitting side-by-side with SIM cards from other providers in the store. It came "pre-loaded" with 35GB of data to use on their network, plus unlimited SMS and voice calling, which was described on the packaging. When I put the SIM in the device I was prompted to go to a website to register my service, where I input a code from the SIM card packet to link the SIM itself. I was asked to provide my driver license number or passport number. I was then able to choose between three pre-selected phone numbers that were displayed on the screen. Click Finish, and my cellular service started working on my phone. Every month I have the option to renew my plan under the same terms, or choose a plan with different terms (more or less GB of data, for instance), or throw the SIM card away and switch to a different wireless provider.