Allan Keiter was vulnerable when he noticed an enticing deal from Sprint. He was tired of his dull, outdated phone, and Sprint was offering a $150 rebate on a sweet, $600 Treo phone/organizer/Web surfer/camera. The catch: He had to commit to a two-year contract, and it would cost him $150 to bail out early. He took the bait. Three weeks after getting the Treo, Keiter lost it in Las Vegas. He was stuck, so he replaced it with a cheap phone from the Sprint store.

Keiter should have known better. He is president of MyRatePlan.com, an Atlanta-based Web site devoted to offering shopping advice and competitive prices on cell phones and plans. "It was a mistake," he says flatly. Carriers prefer to lock you in longer, he says, because it costs about $350, on average, to acquire a new customer. But for consumers, it can be a save-now, pay-more-later proposition if you lose your phone or if rates fall while you're under contract.

Cell-phone companies entice newcomers with free or discounted phones and more-generous plans -- and stiff current customers unless they agree to extend their contracts. So, the shorter your contract, the more frequently you'll be wooed and the more clout you'll have if you need to replace your phone or bargain for more minutes.

There are trade-offs. With a shorter contract, you sometimes pay more for a phone up front, and sometimes the activation fee is higher. For example, Verizon charges the same $175 cancellation fee for one- and two-year terms. But with the one-year plan, you pay $50 more for a phone and $20 more for activation. One-year plans are sometimes tough to find on the carriers' sites -- except at T-Mobile, which offers nothing but one-year plans, all with a scary $200 early-out fee. MyRatePlan.com's rate-plan finder can help you ferret out short-term plans. The site partners with independent retailers, who may have better deals on phones than the carriers but charge additional cancellation fees. Also check out Wirefly.com and SaveOnPhone.com for special offers.

--Mark K. Solheim