'Data stash'? Why T-Mobile doesn't just call it rollover data

When you explain the concept of T-Mobile's Uncarrier 8.0 announcement, "Data Stash," it sounds an awful lot like a rollover program.

That's what Yahoo's David Pogue called it -- several times -- during a webcast interview with T-Mobile CEO John Legere to discuss the announcement. Legere was quick to correct him.

Data Stash, which is available to any new or existing T-Mobile customer who signs up for a phone plan with 3 gigabytes of data or more, allows you to bank any unused data and use it the following month (up to 12 months). It's a modern equivalent to Cingular Wireless' popular rollover program, which let you move excess voice minutes from month to month.

If everyone already knows the concept as a rollover program, why doesn't T-Mobile just call it that? It turns out it can't.

AT&T actually still owns the rights to use the term "rollover." "We own equity in 'rollover' and we have for years," said a spokesman for the company.

T-Mobile, for its part, said it never planned to use the term.

"'Stash' is cooler," Legere said on a media conference call. "'Rollover' is such a 1980s term."

He added, "If you want to call it 'rollover,' that's OK."

Cool or not, the rollover program was a big hit for Cingular and helped it win recognition at a time when the carrier was fighting off fierce rivals such as Verizon Wireless and Sprint.

"That was a huge success for Cingular," T-Mobile Chief Marketing Officer Mike Sievert said in an interview. "They hung their entire hat on that."

The idea of rollover minutes is largely moot, with most programs offering unlimited voice minutes on wireless plans. The idea of rollover data, however, is new and, according to Sievert, a bit of a risk.

"No one's had the guts to do it on data," he said. "It's a big bet."