2:40 PM -- CHICAGO -- 4G World 2011 -- Enjoy your wireless operator's free Wi-Fi while you still can, because it could soon be a thing of the past. Wireless operators will be investing up to nine figures in Wi-Fi by next year, according to a Ruckus Wireless Inc. exec, and they have to recoup it somehow.

Steven Glapa, senior director of field marketing at the Wi-Fi offload vendor, says that most operators are at least exploring how to charge for Wi-Fi now. Most, like AT&T Inc. (NYSE: T), which has 29,000 hot spots, offer it free as a value-added service today. But Glapa says operators, in general, are considering bundling in an extra cost for the off-network access into data plans and counting that usage against the data cap.

“Once they have the policy management in place to integrate Wi-Fi into [their networks], you have those options,” Glapa said in a 4G World interview.

Right now most operators are approaching Wi-Fi as an easy way to dump data traffic off their networks, but as vendors introduce policy management solutions that let them keep an eye on users as they traverse between the networks, it’s becoming possible to track -- and monetize -- subscribers, regardless of what network they are on. (See Wireless Operators Embrace Wi-Fi as Their Own and Mobile Wi-Fi Offload.)

Charging for Wi-Fi seems to be the inevitable next step after doing away with unlimited data plans, but I’d advise the operators to tread carefully. Consumers may be used to paying for hotel and airport access, but they love operator Wi-Fi because it’s free and unlimited. Taking that away is sure to cause a backlash.

Or if they feel they have to charge for Wi-Fi, an extra $5 on the data plan may be forgivable, but also counting that use against the data cap will be a much harder pill to swallow.

— Sarah Reedy, Senior Reporter, Light Reading Mobile