T-Mobile USA

T-Mobile's latest salvo in the ongoing price war among US wireless carriers has cut the price of its unlimited shared data plan to $100 a month, a 29 percent reduction.

Beginning Wednesday, T-Mobile will offer unlimited talk, text and 4G LTE data for two lines on its new Simple Choice plan for $100 a month, T-Mobile announced on its website Monday. Customers can tack on up to eight additional lines for $40 for each line.

"People are saying loud and clear that they hate the confusion and complexity of the carriers' shared data plans, and they should," John Legere, chief executive officer of T-Mobile, said in the statement. "They threaten you with punishing overage penalties unless you police your own family's data usage or up your data bucket and spend more every month."

T-Mobile also announced it is resurrecting a promotion that offered a family of four 10GB of 4G LTE data for $100. Like the previous promotion, which T-Mobile pulled in October, customers will get 2.5GB per line of data until 2016, when the plan switches to 1GB per line.

Part of a cut-throat effort to win new customers and retain existing ones, T-Mobile has been the beneficiary of aggressive moves over the past year and a half. Its Uncarrier campaign and Legere's brash attitude has succeeded in winning over consumers and driving its turnaround and helping add 2.3 million new customers in the last quarter.

But the competition isn't sitting back. Sprint, the nation's third-largest wireless carrier, launched the most recent battle in the price wars in October by introducing a new low-end family data plan aimed at undercutting the top carriers AT&T and Verizon Wireless. Those carriers responded with promotions boosting the amount of data they offered on existing shared plans.

T-Mobile's shares fell by $2.35 to $25.85, an 8.3 percent decline, after announcing Monday that it would launch a mandatory convertible offering in hopes of raising money for general corporate purposes.