Now that Sprint and T-Mobile US are no longer an item, the fight over one another's friends has begun.

It started earlier this week when new Sprint CEO Marcelo Claure made good on his promise to compete more aggressively in the wake of his company's unsuccessful bid to acquire T-Mobile, unveiling the Sprint Family Share Pack – a shared data plan that offers incoming customers at least double the volume of data compared to T-Mobile, AT&T and Verizon, at prices that match or undercut the big two.

The new tariff replaces Sprint's previous shared data plan, 'Framily', which allowed groups of up to 10 friends, family, and even perfect strangers to sign up to the same contract but receive bills to separate addresses.

To entice prospective Family Share Pack customers, Sprint is offering to reimburse up to $350 worth of early termination fees (ETFs) to help them switch from a rival provider, a move introduced to the U.S. by T-Mobile earlier this year.

Never one to miss an opportunity to inject some drama (or should that be melodrama?) into the proceedings, T-Mobile US took umbrage on behalf of existing Sprint customers who are not eligible for their carrier's new price plan.

"It continues to amaze me to see the old carriers failing to listen to their customers − or reward them for their loyalty," said T-Mobile CEO John Legere, in a statement on Thursday. "That arrogance and indifference has defined the U.S. wireless industry for too long."

He urged his customers to take pity on long-suffering Sprint users by bringing them over to T-Mobile. As a reward, T-Mobile is offering the referee and the referrer – provided the latter is on one of the operator's Simple Choice plans – a year of unlimited LTE data.

The offer starts on 29 August. T-Mobile customers need to supply their mobile number and the number of the customer making the switch within 30 days of the new customer's activation.

"Only a 'carrier' would be arrogant enough to make an offer limited only to new prospects, while forgetting their existing customers. The un-carrier way is to