Running through January 7th, the promotion promises that people who switch their wireless service and port their number to Sprint (S) will receive an offer for a plan that costs half of what they currently pay to Verizon (VZ), AT&T (T), or T-Mobile (TMUS). In addition, people who switch carriers will receive a gift card worth up to $650 to cover termination fees and remaining phone payments.

One example provided by the company shows that a subscriber paying $50 per month for 5GB of data on AT&T would get the same amount of data on Sprint for $25. In addition, current Sprint subscribers will receive a free Alcatel tablet—full retail price $168—with a free year of Sprint LTE service.

The deal is similar to the “cut your bill in half” promotion Sprint used to target Verizon and AT&T last year, only this time around, it applies to T-Mobile as well.

For consumers, it’s a deal worth looking into. As the competitive wireless industry continues to jockey for customers, people who shop around can end up with significantly discounted service.

But not everyone is happy about this deal. T-Mobile’s outspoken CEO, John Legere, took to Twitter to denounce Sprint’s latest deal. It’s not the first time Legere has directly addressed his competitor on Twitter.

First, he encouraged people to read Sprint’s fine print:

Why do I love it? Marcelo repeatedly said there are no “gimmicks,” but let’s look at the fine print… shall we? pic.twitter.com/BLsgjC1mMI

— John Legere (@JohnLegere) November 18, 2015

Legere does have a point. Although Sprint CEO Marcelo Claure called the promotion “simple and easy to communicate” on a conference call, there are a few caveats to the deal. The 50% savings doesn’t apply to unlimited plans, and Sprint will only honor the reduced price plans until January 2018.

The rest of Legere’s tweetstorm attacked Sprint’s current corporate troubles, claimed T-Mobile’s network was faster than Sprint’s, and promoted T-Mobile features such as free video streaming.

Did we just witness beginning of the end for @sprint? $2.5B to cut, laying people off, now price cuts? The countdown clock makes sense now!

— John Legere (@JohnLegere) November 18, 2015

10. @TMobile customers get Unlimited video streaming w/ their plans. Not on @Sprint. #SprintCountdown #halfoffthetruth

— John Legere (@JohnLegere) November 18, 2015

3. @TMobile customers get America's Fastest 4G LTE network. @Sprint's get America's slowest (@Ookla). #SprintCountdown #halfoffthetruth

— John Legere (@JohnLegere) November 18, 2015

Sprint is in a precarious position at the moment. While it used to be the third-largest U.S. wireless carrier by number of subscribers, it was passed by T-Mobile earlier this year. In addition, Sprint plans to shed $2 billion in expenses next year, largely through job cuts. Although its subscriber base recently began to grow for the first time in more than two years, it still needs to convince more people to switch to its service, which may have prompted its most recent promotion.

Verizon and AT&T remain firmly in the top two spots, respectively, by number of subscribers.

Claure didn’t miss Legere’s tweets and shot back, focusing on the fact that T-Mobile’s unlimited video streaming service sometimes limits customers to standard definition video, in addition to T-Mobile quietly raising its prices for some of its plans last month.

But on a day where T-Mobile’s outspoken CEO tried to steal the spotlight from Sprint’s promotional push, at least Claure got the last word.

@JohnLegere countdown?only thing going up at @TMobile are prices,what's going down its your quality of service Binge on?More like #cringeon

— Marcelo Claure (@marceloclaure) November 18, 2015

@JohnLegere the only print that matters is the BIG print. @TMobile customers can come and save 50 % of your current rates!! It's that simple

— Marcelo Claure (@marceloclaure) November 18, 2015

@JohnLegere @TMobile forgot to mention we don't throttle our customers to LOW DEF 480p horrible quality video. It's full speed @sprint

— Marcelo Claure (@marceloclaure) November 18, 2015

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