The data coming from cell phones carries with it a huge amount of information about users’ real-world activities and has for years been under lock and key. But now an increasing number of wireless carriers are mining and repurposing that subscriber data to track statistics about how people are living their lives and selling the data to businesses and city planners. This is information that experts believe could change societies.

How so? It “could help cities plan smarter road networks, businesses reach more potential customers, and health officials track diseases,” according to MIT Technology Review. But there’s also a darker possibility and that involves privacy. “…even if shared with the utmost of care to protect anonymity, it could also present new privacy risks for customers,” adds the article.

Verizon has already started selling this data. “In late 2011, the company changed its privacy policy so that it could share anonymous and aggregated subscriber data with outside parties. That made possible the launch of its Precision Market Insights division last October,” notes the article.

“The program, still in its early days, is creating a natural extension of what already happens online, with websites tracking clicks and getting a detailed breakdown of where visitors come from and what they are interested in,” it adds.

And other telecommunications companies are trying similar tactics. “Already, some startups are building businesses by aggregating this kind of data in useful ways, beyond what individual companies may offer,” explains Technology Review.

One such example is AirSage whose “algorithms look for patterns in that location data — mostly to help transportation planners and traffic reports, so far. For example, the software might infer that the owners of devices that spend time in a business park from nine to five are likely at work, so a highway engineer might be able to estimate how much traffic on the local freeway exit is due to commuters.”