You'll never read this, dude, but please... Remember a few things.
1.) When you call someone, never ask, especially brusquely in these exact words: "Who's this?" You'll guarantee to upset someone.
2.) If you've gotten the wrong number, take a second to find out whether or not you dialed incorrectly, or whether or not you actually have the incorrect number.
3.) Lastly, don't persist in #1 if the direct answer to your question doesn't result in the answer you're looking for. When someone calls me, and repeatedly asks "Who's this?" I'm going to continue answering by telling you my name. When you finally respond with "I didn't call you," you've broken the stupid barrier and you will get hung up on.