The big man is averaging 13.0 points, 12.4 rebounds, and 2.2 blocks on the season.
Anderson's contract is a near match to Johnson's and has $21.3 million remaining for the 2019-20 season, though only $15.6 million is guaranteed.
Next season, Johnson's expiring contract can be utilized if the Suns chase after any trades where large salaries are swapped.
Ellington is in his 10th National Basketball Association season and has averaged 8.4 points in 25 games with the Heat this season. He's averaging 8.4 points, 1.9 rebounds and 1.2 assists.
After landing in Phoenix, Ellington and his agent are reportedly working with the Suns toward his release, which would likely come in the form of a buyout, in order to join a playoff contender.
Facebook finally rolls out life-saving 'unsend' feature on Messenger
We've all done it - sending a message or an email to the wrong person that you wish you could jump into your phone to delete . The removed message will be replaced by text alerting everyone in the conversation the message was removed.
Anderson has appeared in just three games since November and is unlikely to be any more involved in Miami.
Johnson, 26, was in his fifth season with Miami since going undrafted in 2014. If no such agreement is reached, the 31-year-old is in the final year of his $6.2 million contract and will become an unrestricted free agent this summer.
The NBA trade deadline is less than 24 hours away and the Miami Heat are now making moves to address some roster issues. He is in the third year of a four-year $80 million deal.
Anderson, 30, is averaging 3.7 points and 3.0 rebounds in his first season in Phoenix, having also played with the Rockets, Pelicans, Magic and Nets in his career.