Learning about cellular connectivity

Cellular connectivity is provided by telecommunication networks. These networks are usually privately owned, although they can be publicly owned in some countries. These networks are licensed at a national level. As a result, even if a network has the same name as a network in another country, you can’t use the other network unless the two networks have a roaming agreement.

In order to connect to a cellular network, you will need a device that is capable of communicating over the right frequency and a Subscriber Identity Module (SIM). A SIM can be either physical or virtual (or electronic). A physical SIM is also called a SIM card. Physical SIM cards have shrunk in size over the years, thus making it possible for device manufacturers to also make smaller devices. A SIM card with cutouts for three generations of sizes is shown in the following figure, with the card itself in the white area.

Figure 9.1 –...