For T-Mobile's next trick, the carrier is offering 4G LTE tablets for the same price as the Wi-Fi versions, and kicking in an extra 1GB of free data for the rest of the year.

A new iPad Air, for example, would cost $499 for a 16GB model with 4G LTE, instead of the usual $629. Samsung's Galaxy Tab 3 would cost $200 instead of $312.

Along with the reduced hardware prices, T-Mobile is offering another 1GB of free data per month through 2014, on top of the 200MB that the carrier already provides. T-Mobile says it will continue to offer the free 200MB for as long as users own their tablets. After this year, the extra 1GB will cost $20 per month.

T-Mobile is only offering these deals to subscribers who also have a smartphone plan, so you won't be able to snag a cheap tablet and free data without switching carriers entirely. To make the switch easier, T-Mobile is still offering to pay your old carrier's early termination fee, along with up to $300 in credit for trading in your old phone.

This is the second of what T-Mobile says are three new initiatives being announced this week. On Wednesday, the carrier announced a new "Simple Starter" plan for $40 per month, which includes 500MB of data and unlimited talk and text. Unlike T-Mobile's higher-priced plans, Simple Starter doesn't offer unlimited data at slower speeds after you hit your limit. Instead, you'll have to purchase a day- or week-long pass for additional data.

T-Mobile's various new plans and polices have triggered a price war among the major wireless carriers, but so far no other carrier has followed T-Mobile into the free tablet data fray. Both AT&T and Verizon charge an extra $10 per month for tablet access as part of their shared data, while Sprint charges $15 per month for 1GB of tablet data. With T-Mobile getting even more aggressive, we'll see if its larger rivals can muster any kind of response.