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T-Mobile announced on Friday that it will be pulling Apple's iPhone 4S and iPhone 5 from its "zero-down" promotion, while AT&T revealed a price cut to iPhones purchased through its "Next" subscription plan.

According to an internal document, T-Mobile is selectively removing Apple's iPhone 4S and iPhone 5 from its "$0 Down" summer sale on Saturday, leaving only the iPhone 4 available for free on signing, reports TmoNews.

The document notes a coming change in iPhone 4S and iPhone 5 pricing makes the smartphones ineligible for the ongoing "$0 Down" sale. Under the revised structure, customers will pay $145.99 upfront for a 16GB iPhone 5, followed by payments of $21 per month for 24 months.

"As is the nature of promotions, pricing moves are temporary," a T-Mobile representative told AllThingsD. ""However, combined with our Simple Choice plan, it's easily one of the most affordable ways to purchase the latest iPhone."

No explanation was given as to why T-Mobile is no longer including the two iPhone models in its summer sale.

After announcing strong quarterly results on Thursday, CEO John Legere said T-Mobile's performance was thanks to the company's message and service, not the recent addition of the iPhone to the telecom's smartphone lineup. Apple's handset accounted for 21 percent of T-Mobile's smartphone sales for the quarter.

Countering T-Mobile's news on Friday, U.S. No. 2 carrier AT&T announced it is cutting the price of iPhones offered through its Next plan, including the latest iPhone 5. With Next, customers pay no upfront fees in exchange for a loss of carrier subsidies.

AT&T Next now offers a 16GB iPhone 5 for $0 down and 20 monthly payments of $27 per month.