"Whom are you calling?"
Translation:Do kogo dzwonisz?
While Polish is pretty flexible with its word order (despite the fact that some orders only work in specific situation, like poetry and songs), there are still some rules that put some limitations.
One of them is that a preposition should come directly before the word it is referring to. „Do kogo dzwonisz?” is the normal order, „Dzwonisz do kogo?” is also grammatically correct and might be used to express surprise at who the person that is being called is. All the other word orders are wrong, because „do” would no longer stand in front of „kogo”.