How is it that by just putting a SIM card into your phone you have access to 4G/5G?
In: Technology
The phone always has the ability to connect to the cell system.
In fact, in the United States, its actually legally mandated that emergency calls (911 and, sometimes, local police and fire numbers) always connect even if the phone has no valid plan. Obviously, this law does not mandate there be actual coverage for your location, but, if the phone can connect to a tower, the tower *must* accept the connection and connect you to the emergency system.
What the SIM card does is give the phone an unique subscriber number (fyi, SIM stands for “Subscriber Identity Module”) that the cell system uses to identify the phone so the network can link your phone to your plan. With this, the cell network knows whether you are part of their network or not, and if not, how to bill your provider for your usage. The network can also use this data to throttle your usage or otherwise limit your access based on your plan.
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