Last time on our explainer show Upscaled, we took a look at 5G, the new high-speed mobile technology starting to roll out in 2020. But 5G isn't entirely new technology, it builds on the mobile networks already in place around the world. This has been the pattern for mobile networks, incremental upgrades that added more capacity and speed bit by bit. This approach has yielded incredible results; as much as we might gripe about coverage or speeds today, the first real cell networks could only support about a dozen calls per tower, had no data capacity, and used unencrypted analog signals that were easy to intercept.