Look at the recipe, it is impossible for milk powder to foam without special treatment. Unless it has something added to it that releases carbon dioxide, which will foam on contact with water.

Normal frothy coffee is made with fresh milk that is steam-beaten to make milk froth. It is also whipped with something that has a motor like a stirring stick. Some of Nestle's half or whole milk powders also froth with the above, skimmed ones do not.