Sprint guarantees $200 trade-in credit to T-Mobile customers

Sprint has fired a shot over competitor T-Mobile's bow.

Between now and April 9, T-Mobile subscribers can walk into a Sprint store and immediately receive at least $200 in credit for any working smartphone if they switch to Sprint's network, the company announced Friday. Sprint's deal can also be combined with a contract-buyout offer in which Sprint gives T-Mobile customers up to $350 per line to cover costs associated with switching carriers.

Sprint's offer shows that everything's on the table in the mobile industry right now. A key component in T-Mobile's market strategy in recent years has been to go head-to-head with the big-three: AT&T, Verizon and Sprint. T-Mobile has similar offers that guarantee trade-in amounts on smartphones and that wipe out early-termination fees.

T-Mobile's efforts seem to be paying off. Earlier this week, research firm Consumer Intelligence Research Partners announced that T-Mobile's subscriber base grew by 29 percent during the fourth quarter, easily outpacing its competitors and putting it slightly ahead of Sprint to make it the No. 3 cellular provider in the US. Both companies have about 56 million subscribers at last count.

In a series of tweets, outspoken T-Mobile CEO John Legere held nothing back in his opinions on Sprint's latest move and highlighted his company's growth.

"It makes sense, @Sprint has to target @TMobile when we're winning with 1.3M postpaid [subscriber additions] and they only had 30k in Q4," Legere tweeted. He continued his tirade, saying that he believes Sprint is "desperate" after T-Mobile announced on Thursday that it would no longer save the best deals for those who have strong credit quality in a move it's calling Smartphone Equality. The move is a major departure from the industry, which has long been cognizant of subscriber credit scores when offering top deals.

"But in all [honesty], this is great news for @Sprint," Legere tweeted. "They are closer to offering what we offer. Except on a s***** network."

The fact that Sprint is so willing to take the fight to T-Mobile may indeed speak to the latter's growing success. However, Sprint's announcement painted the move as simply part of its trade-in program and noted that it bought back 3 million phones last year. Sprint also said in response to Legere's comments that his tweets suggest the move might have been a good one.

"He seems pretty concerned," a spokesman told CNET on Friday. "This is an offer that makes sense and is a good deal."

It's unclear whether Sprint's move will have a profound impact on T-Mobile's business. As part of its "Uncarrier" program, T-Mobile will match trade-in pricing from other carriers. So, it's possible that the company could match whatever deal Sprint offers. Interestingly, Sprint also has a matching program, so it's even possible that a price war could erupt for customers who are willing to walk back and forth between stores.

Update 12:42 p.m. PT to include comments from Legere and Sprint.