Assuming you store the number of calls in an attribute, create a second attribute which is a ranking value. Set up a process to calculate ranking.
Initialize all to rank 0.
Find those with most calls, set to rank 2.
Find those with least calls, set to rank 1.
Then your query selects all with rank greater than 0. Display either asc or desc and put on item rules to colour 1 say red and 2 to say green. Also put an icon on the rank say tick for rank 2 and cross for rank 1. You can also schedule process so that it keeps giving latest results.
Lots of other ways to do this!
Cheers Rod