T-Mobile US, AT&T and Verizon Wireless, touting their new installment-plan approach to mobile-phone pricing, will offer Apple Inc.'s (AAPL) iPhone 5C without an initial down payment.

T-Mobile will subsequently require 24 months of $22 payments, the Bellevue, Wash.-based company said on its website. AT&T's $22 installment plan will only last 20 months, though its service prices start at a higher rate. And Verizon is offering the 5C without a down payment and $22.91 per month over 24 months, according to its website.

The debut of the new iPhones, due in stores later this month, is putting a spotlight on the industry's shift toward more flexible installment purchases, as an alternative to the subsidized $200 phone, with a 2-year contract . T-Mobile, the fourth-largest U.S. carrier, was first to adopt the approach earlier this year, seeking to stand out from its larger rivals. Verizon Wireless and AT&T then followed with similar plans.

"I think these plans are here to stay," said Jennifer Fritzsche, an analyst at Wells Fargo & Co. in Chicago. "It's very good for the carriers since it decreases their subsidy costs and takes some pressure off their hardware expenses."

While T-Mobile no longer offers discounted phones tied to contracts, the other major carriers still offer the traditional method of subsidizing phones in exchange for two-year service plans.

The higher-end iPhone 5S will sell for $99 down and $22.91 a month at T-Mobile, while AT&T will offer it for zero down and 20 monthly payments of $27. Verizon hasn't determined an installment plan price for the 5S yet. Verizon and AT&T will offer the iPhone 5S starting at $199 with a two-year contract.

While the total cost of buying the iPhone through AT&T, for example, is lower, T-Mobile aims to attract customers with its service plans. The company charges $70 a month for unlimited calling, text and data. AT&T, which no longer offers unlimited data, has a starting price of $80 a month, with caps on calling minutes and data.

T-Mobile shares declined 2.9 percent to $24.71 and AT&T fell 5 cents to $34.32 at 4:10 p.m. in New York. Verizon gained 0.9 percent to $47.76.

"This represents a significant moment for people to rethink who their carrier is and switch to T-Mobile," said T- Mobile Chief Marketing Officer Mike Sievert. "People have been waiting, either because they are stuck in contracts, or waiting for the new iPhone."

Sprint, the third-largest U.S. carrier, will offer both handsets starting Sept. 20 on a two-year service agreement. The cheapest model 5C will sell for $99.99 while the 5S will start at $199.99, the Overland Park, Kansas-based company said in a statement.