Some T-Mobile (NYSE:TMUS) users reported seeing a message saying "Facebook (NASDAQ: FB) with Free Data" when they logged in to their accounts on the social network yesterday, according to TMoNews. But unlike AT&T and Verizon, the carrier says it has no sponsored data offering.

TMoNews reported that the banner message appeared both in the Facebook app and on the social network's website, and users were warned that "standard data charges may apply" when they navigated off Facebook's properties.

A T-Mobile representative said flatly that the carrier doesn't support a sponsored data program, although the carrier's prepaid GoSmart service does offer zero-rated content from Facebook and Facebook Messenger. Facebook representatives declined to respond to an inquiry from FierceWireless on the topic.

T-Mobile offers zero-rated video in the form of Binge On, which has gained traction with users even as it has been criticized for running afoul of net neutrality principles. The carrier also offers Music Freedom, which provides tunes from 40 content providers to users without incurring data charges.

But the nation's third-largest mobile operator has yet to launch a sponsored data service, unlike its two larger rivals. Verizon recently launched sponsored video through its new FreeBee Data service, enabling content providers to pay the cost of delivering their wares to users over its network. And AT&T has been experimenting with sponsored data for more than a year.

Critics claim zero-rated data offerings violate net neutrality laws because they favor deep-pocketed content providers who can afford to pay data costs or to meet carriers' technical requirements. Such policies are unfair to smaller content providers, some claim, who risk being elbowed out of the market.

For more:

- see this TMoNews report

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