Cellular, for the people, may have finally arrived—and I put that claim on trial with Walter: a tiny open-source cellular board that mashes GPS + LTE-M + NB-IoT with WiFi and Bluetooth on an ESP32-S3. This isn’t a phone module. It’s built for everything else: trackers, sensors, remote monitors, and real IoT deployments where power draw and lock-in actually matter. I break down the real-world differences between LoRa/Sigfox vs NB-IoT vs LTE-M (bandwidth, latency, penetration), and why LTE-M is the sweet spot when you need two-way comms, faster sync, and even firmware updates. Then I take Walter out of the lab and into live environments: my apartment window (GPS fix + LTE-M upload), a moving car (real-time map tracking with a GPS fix in ~4 seconds—even through glass), and a brutal concrete stairwell where GPS dies but LTE still punches through. The big takeaway: Walter is optimized for the 99% of the time your device is asleep, hitting ~9.5 µA deep sleep with the modem in PSM. I also cover SIM options that don’t feel like a subscription trap—like ONCE’s one-time model—and how providers like Hologram matter if you want fleet control and global coverage. And if you’re truly off-grid with zero towers, I point you to the Meshtastic path with my Houdini builds.