Mobile Adapter GB

The Mobile Adapter GB was a short-lived peripheral developed by Nintendo that allowed the handheld Game Boy Color and Game Boy Advance consoles to connect to a mobile phone and utilize its cellular network. The accessory used a proprietary networking service called Mobile System GB operated by KDDI to exchange data. Following delays, the device and service launched in Japan on 27 January 2001. Together, they enabled online functionality for roughly 20 games, most notably Pokémon Crystal and Mobile Golf. Nintendo and Konami formed a joint venture, Mobile21, to create games that utilized the service.

Nintendo ultimately chose not to release the adapter outside Japan, citing international wireless incompatibilities and market differences. Its high costs and limited game compatibility hindered widespread adoption, with only 80,000 units sold in its first year. The service was discontinued after less than two years on 18 December 2002, marking an early, albeit unsuccessful, attempt at handheld online gaming. It would be succeeded on the company's later handheld systems by services such as Nintendo Wi-Fi Connection, Nintendo Network and Nintendo Switch Online.