At the end of April, T-Mobile and Sprint officially announced merger plans to the tune of $26B. Now, the DOJ is reportedly investigating how the deal could affect small carriers, particularly MVNOs.

In a new report from Reuters, the US Justice Department is said to be probing how a merger of the 3rd and 4th most popular carriers could affect small wireless providers.

T-Mobile and Sprint have been selling the majority of network access to mobile virtual network operators (MVNOs) like Boost Mobile, Straight Talk, Net 10, and more. If the merger does go through, there will be less choice and competition in the network access market, so the DOJ has been asking for input from the smaller carriers on the matter, say anonymous sources.

Representatives from the DOJ and T-Mobile declined to comment on the latest news, while Sprint has yet to respond to Reuters.