Now that the FCC Chairman has thrown his support behind T-Mobile and Sprint's merger, the two carriers must get the approval from the Department of Justice. According to a new report, though, they may have to take extra steps on top of the concessions they've already made to convince the DOJ to approve the deal.

The DOJ has told T-Mobile and Sprint that it wants them to help create a new wireless carrier, complete with its own network, before it'll approve their merger. That's according to sources speaking to Bloomberg, who add that DOJ antitrust head Makan Delrahim wants four carriers and hasn't been swayed by T-Mo and Sprint's arguments that they'll become a strong number three competitor to AT&T and Verizon.

Discussions between T-Mobile, Sprint, and the DOJ are described as being "productive" and the DOJ reportedly hasn't reached a final decision on the deal.

T-Mobile and Sprint have already committed to selling Boost Mobile if their merger is approved, along with meeting 5G and in-home broadband rollout goals and committing to not raise prices for three years. Those concessions apparently aren't enough for the DOJ and its antitrust chief, though.

Helping to create a fourth U.S. carrier with its own network is a big ask for T-Mobile and Sprint, but the carriers are so close to getting their merger approved that they might go through with it. If they don't, the DOJ might sue to block their merger from happening, and there are some state attorneys general who are concerned about the T-Mobile and Sprint merger's effect on competition that could join in on a lawsuit or possibly sue even if the DOJ approves the deal.