Major wireless service providers in the U.S. have struck a deal with the Federal Communications Commission to warn customers about impending overage charges for voice, text and data use. Under the voluntary industry guidelines, developed under the threat of new government regulations, customers will receive free text alerts in real-time when they're about to exceed their limits or if they are about to incur in pricey international roaming fees.

The move is aimed at reducing hefty and unexpected charges for cell phone usage -- or what consumer advocates call bill shock.

"Far too many Americans know what it's like to open up their cellphone bill and be shocked by hundreds or even thousands of dollars in unexpected fees and charges," President Barack Obama said in a statement. "Our phones shouldn't cost us more than the monthly rent or mortgage."

The FCC first proposed mandating bill shock countermeasures a year ago. At the time, the commission proposed rules that included over-the-limit and out-of-the-country alerts, as well as giving customers an easy way to cap their own usage so they'd never get hit with overage charges. The measures that wireless carriers are implementing voluntarily only include the former but apparently will be enough to avoid that mandate and maintain their profitable overage fees.

As Time notes, some providers including AT&T and Verizon Wireless already warn their customers as their data use approaches the limit, but they do so with a 24 hour delay. The agreement for real-time alerts will require wireless providers to speed up their systems and have a solution in place within 18 months.

An FCC survey last year found that 1 in 6 wireless customers have seen unexpected spikes in their bills and most of those people weren't alerted ahead of time. What has been your experience with overage fees: Have you ever suffered from "bill shock"? Do you use any kind of special apps for monitoring your own usage?