There are a handful of mobile virtual network operators (MVNOs) that operate over AT&T’s network. These services offer coverage that is similar to what AT&T offers its own subscribers, but service from MVNOs is often much cheaper than service purchased directly from AT&T.
List of AT&T MVNOs
|Red Pocket Mobile||200,000|
|NET10 Wireless*||3,000,000||NET10 is part of TracFone|
|TracFone||Additional subscribers may use other carriers that are part of TracFone. An América Móvil (TracFone's parent company) report covering performance in the 4th quarter of 2018 indicates the company had roughly 22 million lines in the U.S.|
|Straight Talk*||9,000,000||Straight Talk is a TracFone brand.|
|Clearway Wireless*||Clearway is a TracFone brand. I believe Clearway works with all of the Big Four networks, but I'm not confident.|