A patent filed by Nintendo reveals that the company has been interested in phone games since as far back as 2001, although it looks like it was interested in making hardware in addition to games.
The patent also depicts what might appear on-screen, including a look at Mario and a menu from which you would select games.
Presumably, the phone would have allowed you to play Nintendo games, including the Game Boy classic, “Metoroid 2.”
The filing, which was uncovered by Reddit user NintendoGamer1997, shows a cell phone with a D-pad and an A and B button along with the standard touch tone keypad.