T-Mobile has lost its bid to dismiss a class action lawsuit attempting to undo its $26 billion merger with Sprint.

As reported by Reuters, the carrier will now have to face the court case after its appeal against it was rejected.

The class action suit on behalf of millions of consumers claims that AT&T and Verizon subscribers have had to pay billions of dollars extra for wireless service after the merger reduced competition by cutting the number of US mobile from four to three.

The proposed suit was filed last year and seeks a range of penalties, the most severe of which is the undoing of the merger.

In a court order yesterday, the Chicago-based 7th US Circuit Court of Appeals denied T-Mobile’s request to appeal a decision that argues plaintiffs have a legal "standing" to prove their claims the merger has increased prices for wireless services.

Illinois District Judge Thomas Durkin said in November that the plaintiffs "plausibly" argued that higher prices stemmed directly from the deal.

However, in March he ruled that T-Mobile could appeal his order, noting that the plaintiffs’ had not sufficiently alleged antitrust standing. T-Mobile was unsuccessful.

"We look forward to developing the record and trying the case to a jury in Chicago," said Brendan Glackin, an attorney for the plaintiffs.

T-Mobile hasn't commented as of yet, but has previously called the claims "speculative."

The merger with Sprint was first announced in 2018, and subsequently completed in 2020. The deal faced scrutiny from regulators but was eventually cleared.