He also played 11 games in the National Hockey League (NHL) for the Dallas Stars during the 2007–08 and 2008–9 seasons.

As a youth, he played in the 1997 and 1998 Quebec International Pee-Wee Hockey Tournaments with a team from Zürich.

[citation needed] He is the fourth Swiss goalie who has been drafted by an NHL team after Pauli Jaks, David Aebischer and Martin Gerber.

[citation needed] Stephan made his first career NHL start on 13 October 2007 against the Chicago Blackhawks, since both of the Stars' goaltenders — Marty Turco and Mike Smith — were injured.

[citation needed] At the conclusion of the 2018–19 season, Stephan joined Lausanne HC on a three-year deal worth CHF 3 million.