“Stop burning data when you stream music,” T-Mobile (TMUS) proclaims in a recent promotion. The mobile carrier’s pitch sounds simple enough—streaming songs won’t count against a subscriber’s monthly data plan. But for the FCC and the telecom industry, the offer is a hornet’s nest. The issue? Such plans are technically violations of “net neutrality,” a policy that forbids Internet providers from favoring some types of web traffic over others.
In February, after a bruising political battle, the FCC declared that net neutrality is the law of the land. But the fight was fought over Internet providers slowing down websites—not the use of financial incentives to encourage choosing some types of content over others. It’s only the tip of the iceberg.
Mobile giants AT&T (T) and Verizon (VZ) plan to swallow video companies (DirecTV (DTV) and AOL (AOL), respectively) whole, meaning we may soon see offers that let subscribers watch certain shows free of data caps. Consumer-friendly? Sure. But critics suspect it could be a back door for the content discrimination that net neutrality is supposed to prevent.
A version of this article appears in the June 15, 2015 issue of Fortune magazine with the headline ‘A New Fight For Net Neutrality.’