It was announced as part of a broader roaming benefits announcement a few months ago that T-Mobile would be working to have wifi benefits for subscribers on UA flights. Tmo previously offered Gogo wifi benefits but Gogo is being used less and less on DL and AA. I took advantage of the new 5GB international roaming benefit recently.

Magenta Max customers will get unlimited wifi, but Magenta only an hour. Assume this hour is per flight but haven't seen details.