T-Mobile today announced that customers who “rescue” subscribers from AT&T, Sprint or Verizon will earn one year of unlimited data from themselves and their friend.

Beginning next week, subscribers who port over their number to T-Mobile and an existing T-Mobile subscriber will earn unlimited LTE or, if they already have unlimited data, a $10 monthly credit for 12 months.

The deal is for Simple Choice customers only and not available for prepaid.

The deal is targeted at all the other big carriers but the harshest words in the press release were directed at Sprint. Sprint earlier this week announced new family share plans including a limited-time offer of $100 a month for up to 10 lines with unlimited talk and text plus up to 40GB.

T-Mobile CMO Mike Sievert chided Sprint for limiting to the offer to new customers only and seemingly phasing out unlimited data.

“When we saw how Sprint’s dissing its own customers and dropping unlimited LTE plans for families, we knew we had an opportunity to help these people out,” Sievert said in a statement.  “Only a ‘carrier’ would be arrogant enough to make an offer limited only to new prospects, while forgetting their existing customers.”

A Sprint spokesman said that existing Sprint Framily plan customers can switch to a Family Share Pack. All lines on an existing customer’s account can move if they meet one of the following conditions: one line was purchased through Sprint Easy Pay; one line is no longer under a term agreement; one line is upgrade eligible and you are upgrading to a new device; add a new line of service to your account.

The spokesperson said customers meeting one of those requirements can pick a Share Pack data bucket and then pay the un-subsidized access fee of $15 or $25.

Sprint still offers unlimited data plans but its high-profile push for the new shared data packs seems to suggest the carrier is trying to move customers toward data caps.

T-Mobile’s unlimited data policies recently came under fire when reports surfaced claiming the carrier would throttle unlimited subscribers who misuse mobile data for activities like peer-to-peer file sharing. T-Mobile said it would not throttle those customers, clarifying instead it would contact anyone in violation of those rules.

Across all major carriers, network prioritization practices have been called into question. FCC Chairman Tom Wheeler specifically called out Verizon for the practice, which entails slowing down the top five percent of data users when network sites become congested. Sprint and T-Mobile both engage in similar network management techniques and AT&T warns that unlimited data customers might experience slower speeds once they exceed data limits during a billing cycle.