Now that their proposed merger is off the table, tension is increasing between Sprint and T-Mobile as both operators today (21 August) announced unlimited data plan offers designed to steal each other’s thunder.

T-Mobile US is to offer a year’s unlimited LTE data to any of its ‘Simple Choice’ customers who can sign up Sprint users. Subscribers signed on by T-Mobile US customers also receive a year’s unlimited LTE data.

Meanwhile Sprint, under new CEO Marcelo Claure, announced the ‘Sprint $60 Unlimited Plan’, which provides unlimited talk, text and data (and is $20 cheaper than T-Mobile US’ comparable unlimited offer).

In a sideswipe at T-Mobile US, Sprint says customers don’t have to “jump through T-Mobile’s hoops and recruit their friends” to take advantage of the unlimited offer. The new plan comes only days after Sprint revamped its data tariffs.

T-Mobile US’ offer does extend to winning customers over from AT&T and Verizon, but a press release from the self-styled ‘uncarrier’ – which appears to have been crafted by outspoken CEO John Legere – singles out Sprint for particular criticism.

“Sprint’s customers have suffered much,” it reads. “They’ve endured the Framily. They’ve endured America’s slowest nationwide LTE network. And now again, the (ironically named) carrier has forsaken its loyal customers, offering its latest, ‘best deals’ to everyone but its own current customers. It’s hard to watch.”

T-Mobile Simple Choice customers who already have unlimited LTE data receive a $10 credit each month for twelve months if they can up someone from  a rival. The ‘rescue programme’ starts 29 August.

Sprint’s unlimited offer begins 22 August. The third-largest operator stressed that the $60 deal is available to both existing “loyal customers” and new customers.

“With the new Sprint Family Share pack and now the Sprint $60 Unlimited Plan, Sprint is giving consumers what they want: choice, simplicity and value,” Claure claimed.