The Mobile Adapter GB was a peripheral that allowed you to connect a Game Boy to a Mobile Phone, with the purpose of facilitating Internet connectivity and multiplayer. Unbeknownst to many, this was the first time big-name games like Pokémon and Mario Kart had any sort of online connectivity. However, the adapter was a flop, and it never left Japan. Now, 20 years later, the REON team is documenting and restoring the system, across the whole stack, from hardware to backend. This talk will start by covering what the Mobile Adapter GB is, and what REON is doing to restore its functionalities on both software emulators and hardware devices. Then, the discussion will delve into the details by brushing a bit on the peripheral's history, and what it's used for in different games. Finally, the presentation will end with an exploration of how the actual system works: this will help emulator developers understand how to implement the adapter, and it will also show prospective homebrew developers the peripheral's capabilities.