Sprint's crazy-low $15 unlimited plan is going away on Friday

Sprint's latest deal was too good to last. But it's surprising just how quickly it's going away. 

A week ago, the nation's fourth-largest wireless carrier introduced a promotional $15 unlimited data plan, with few strings, and no plans to ever see a price increase. That dirt-cheap price wasn't feasible in the long term, and Sprint is shutting it down. The promotion will last until 8:59 p.m. PT/11:59 p.m. ET on Friday. 

The $15 plan was significantly cheaper than any plan offered by the major carriers, and even undercut the low-cost prepaid players. Sprint, which has a deal to merge with T-Mobile, saw it more of a marketing tool to persuade users to switch and experience the improvements made to its network. Sprint has spent more than the last decade fighting the perception that its service lags far behind its rivals. 

The news comes as Verizon launched an even more expensive unlimited data plan with perks like more high-speed data. 

The executives behind Sprint's "Kickstart" program had a target for customers in mind, and the company hit that goal already, according to a person familiar with the company's plans. 

Sprint will continue to explore different promotions like Kickstart to drum up interest in the service, the person said. 

Until then, you don't have a lot of time if you want to take advantage of the deal. 

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