When telecom and tech leaders convene in Barcelona for Mobile World Congress this week, one topic will rise above the rest: regulation.

Around the world, governments have different approaches to rule-making around the issue of net neutrality—the idea that all traffic be treated equally—a critical issue for mobile-device makers, telecom network providers and content distributors.

The U.S. Federal Communications Commission on Thursday voted that broadband providers should be regulated as public utilities, an attempt to prevent commercial interests from interfering with traffic and a major shift after decades of laissez-faire policy. The question is how will the new aggressive U.S. policy affect the rest of the world.

FCC Chairman Tom Wheeler will give a live keynote address at the annual conference on Tuesday night. It will be his first public appearance at an industry gathering after last week’s landmark vote.

In the U.S., the new rules were greeted with a mixed response. Netflix Inc. said it was a victory, while cable-industry groups said the decision would stifle innovation. Mr. Wheeler has already tried to play down concerns, saying the regulations protect innovation and wouldn’t cut the revenue of broadband providers.