Competition is heating up. We help you choose the best deal. By Lisa Gerstner, Contributing Editor From Kiplinger's Personal Finance, April 2014 1. The battle has begun. In January, AT&T announced that, for a limited time, T-Mobile customers could get up to $450 in store credit for trading in their smart phones and switching to AT&T wireless. T-Mobile soon shot back with its own offer: Customers who moved to T-Mobile from AT&T, Sprint or Verizon could get up to $350 per line in credit to apply to contract early-termination fees, plus up to $300 in phone trade-in value. AT&T has ended its offer, but T-Mobile is still trolling for new customers. SEE ALSO: Should You Switch Cell-Phone Carriers? Sponsored Content 2. Choose sides carefully. Advertisement With T-Mobile’s offer, you must buy a full-price phone from the carrier; activating your own device isn’t an option. Though AT&T is no longer paying T-Mobile customers to switch, you could take advantage of the options that were available through the promotion and avoid a contract: buying a new phone from the carrier at full price (a full-price 16-gigabyte Samsung Galaxy S4, for example, runs $640), signing up for AT&T’s early-upgrade program or activating your own compatible device. Paying in full for a phone could be a good deal even without a cash credit, as long as plan rates drop by the same amount as or more than the increased phone cost, says Phil Goldstein, editor of industry newsletter FierceWireless. 3. Know the cost of freedom. T-Mobile has eliminated contracts and phone subsidies and lowered prices on its service plans. AT&T has introduced Mobile Share Value: no-contract plans that run $15 less per month per phone than contract plans for customers who bring their own devices or pay in full to buy new ones. Plus, AT&T, T-Mobile and Verizon are all touting special no-contract plans that allow frequent phone upgrades and spread payments on a phone over a designated number of months. Such plans may appeal to people who crave the latest devices, but they can be costly. 4. Outfit yourself with the latest gear. Advertisement Popular smart phones, such as the iPhone and Samsung Galaxy devices, are available through all the major carriers now, says Logan Abbott, president of MyRatePlan.com. Or you may choose to bring your own phone, such as a device you purchased from the carrier in the past or one you bought from a third party. But your phone has to be compatible with the carrier’s network. Check the carrier’s Web site or call the customer-service line to make sure the phone you want to use will work. 5. Don’t forget about coverage. Grabbing a great deal on a phone plan probably won’t be worthwhile if your voice and data service is weak. Even Verizon, known for its superior coverage, admitted last year that its 4G LTE data network was struggling to keep up with demand. Your best bet is to ask other people in your area how satisfied they are with their service. You can also look up your city at www.rootmetrics.com/check-coverage to see a map showing how well various carriers perform. 6. Plot your strategy. Advertisement Though picking through the stream of new wireless offers can be tricky, “it’s a great time to be a consumer,” says Maggie Reardon, author of CNET.com’s “Ask Maggie” column. Run the numbers to see whether a plan that interests you will save you money, and keep an eye out for promotional deals. Also check whether you can get discounts at certain carriers based on your employer.