A federal district court in Texas has sided with T-Mobile and ordered Aio Wireless to stop some use of its “plum” color.aio wireless at&t t-mobile cricket

The court concluded Aio’s use of “broad swaths or blocks of its plum color” is likely to cause confusion and that the “loss of goodwill and potential customers poses a substantial threat of irreparable injury to T-Mobile.” That threat, the court said, outweighed the costs Aio will incur in ceasing the above described use of plum in its ads, websites and stores.

T-Mobile applauded the court’s decision to stop “AT&T's transparent effort to infringe on T-Mobile's distinctive magenta trademark,” in a statement.

“While we disagree with the court's decision, it addresses advertising and store designs that we are no longer implementing. Accordingly, this decision has no effect on our advertising plans,” said Alejandra Arango, director of media relations at Aio Wireless.

AT&T is in the process of finalizing its acquisition of Leap Wireless and the Cricket prepaid brand. AT&T stated that Aio Wireless will be rebranded as Cricket once the merger is complete.

AT&T last year launched the Aio Wireless prepaid brand in a limited amount of markets. T-Mobile filed for trademark infringement several months after the initial launch. When the initial complaint was filed, Aio’s response was that “T-Mobile needed an art lesson,” adding that the company doesn’t use magenta.

But the court ruled that Aio wanted to “capture T-Mobile customers,” and in turn granted T-Mobile’s request for a preliminary injunction.