The delay reportedly comes after the US Justice Department's Antitrust Division chief said he hasn't decided whether to approve the transaction. That's not entirely surprising, as earlier this month, the Justice Department said it is unlikely to approve the merger without major changes. While the department hasn't revealed its specific concerns, Reuters says the Antitrust Division is reviewing the argument that the deal would lead to better, faster 5G.

The two wireless providers officially announced the deal last April, but it was clear from the beginning that it would face serious regulatory challenges and intense federal scrutiny. T-Mobile and Sprint hoped to have the deal approved before July (and aimed for April before that). It's unclear just how many delays the companies will put up with, but there's no talk yet of scrapping this merger as they've done with plans in the past.