Initially, both Joe and Anthony Russo wanted that moment to be a fun Easter Egg for fans.
So, if you were one of the savvy Avengers: Infinity War viewers who were able to remember the number, you were probably hoping that calling the number would lead you down a rabbit hole to Steve Rogers and yield some fun results.
For example, the Carrie remake a few years ago asked fans to call a number to “learn what happened to Carrie.”
The Infinity War number would have been even more exciting, because it actually flashed on the screen during the movie, and would have been something that viewers could have taken home with them and talked about afterward.