The call is coming from inside the movies.
This supercut makes fantastic use of many, many different movie phone calls, letting characters from 57 different movies speak to each other.
It's a really well done mashup by Burger Fiction that lets every line lead towards the next one in a really artistic fashion.
What would Scarface say to Napoleon Dynamite? Probably something angry and c0caine-fueled, but you'll have to just watch the supercut to find out.