On Nov. 24, cellphone users will gain the power to tell their service providers, “I’m leaving – and I’m taking my phone number with me.”

The Federal Communications Commission also decided this week that customers will be able to move their wired home or business numbers to cellphones, opening the door for more people to cut the cord and go wireless-only.

So listen up, cellphone users: Where there’s chaos, there’s opportunity. Smart shoppers who understand the ins and outs of portability will be able to save money or negotiate nice deals.

Heavy users of wireless should consider using their new leverage to get a discount on a new phone, or even breaking a current contract and paying the early termination fee.

Local-number portability shifts a bit of power away from wireless providers and toward the estimated 140 million U.S. cellphone users.

The clearest example of the shift comes from New York, where the city has set up an area on its Web site and a phone number people can use to report poor wireless coverage. The city plans to publish the information on Nov. 24.

What does all this mean for you? There’s an old episode of the TV show “Seinfeld” where George and Jerry discuss what it means to be in command in a relationship. They call it “having hand.”

Suddenly with portability, more cellphone users have hand.

Not everyone, though. In the long-distance telephone wars of yesteryear, AT&T, MCI and Sprint would interrupt dinner and offer deals to almost anyone who would switch. But in the coming melee, wireless carriers aren’t interested in competing over every customer, said Martin Dunsby, vice president of sales and operations for inCode, a company in San Diego that does consulting work for wireless providers and large businesses.

In some cases, your carrier might secretly look forward to losing you.

To prepare yourself for the new cellphone reality – and figure out how much hand you have with your carrier – it helps to know a little about how the wireless phone business works.

Two of the major terms to know: “ARPU” stands for “average revenue per user”; wireless providers like it to be high. “Churn” is the percent of users who leave every month; providers like that number to be low.

So when portability hits, a wireless provider’s worst nightmare is for their highest-revenue customers to churn.

On average, major carriers such as Verizon, AT&T and Cingular spend between $375 and $450 to sign you up. The money goes for advertisements, commissions for the stores that sell people phones and discounts on the phone’s price. As a general rule then, carriers start the game $350 in the hole.

Wireless industry executives estimate that wireless providers generally don’t start making money until customers start spending more than $30 per month on their wireless plans.

If you spend more than $50 per month on your wireless plan, you talk a lot in a city where your carrier has good coverage, and you rarely call customer service, you’re a model customer.

If your plan costs less than $50 per month, you talk a lot in the suburbs where coverage is spottier and you always have questions about your bill, you’re not as high on a carrier’s list of subscribers to keep.