Babel

The attempt to build the Tower of Babel had angered God who, in his anger, made each person involved speak a different language which ultimately halted the project and scattered and disconnected the people across the planet.

Regarding the phone call at the end. How'd Amelia get back into the US?
She didn't. The story is told non-linearly. Amelia's story happens, infact, after the Moroccan story. Both stories, however, are told at the same time. This is why the phone call at the end is the phone call we see at the very beginning. Only then, Amelia and the young boy are shown (he talks about the animals which were brought into school, Richard begins to cry, etc.).

A white, American woman is accidentally shot in Morocco (a predominately Muslim country), and that tiny spark erupts a worldwide flame of fury. The American government is quick to play the "terrorism" card, and suddenly Morocco is engulfed in American State Department officials who scour the mountains for the killers.Meanwhile, a Mexican housekeeper is forced to bring American children over the border with her, and a deaf-mute girl in Japan who's dying of loneliness and alienation has no idea that she's part of the global story of the American in Morocco."Babel" is a highly rare and highly intelligent film that is able to seamlessly sew together vastly different story lines, spanning multiple countries and multiple languages. The first world is shown along side the third world, and people in Mexico, Los Angeles, Morocco, and Japan all flow together into one story of angry, ignorant, masculine rage. If this truly is the state of the world, then we really are in trouble.