Let's be honest, what's really killing you is the lack of social antennas. I've been next to a baby that was on full wailing for quite some time, despite the mother's best efforts and that was considerably worse than any idiot yapping on the phone. Didn't really want to make me throw myself or the baby off the plane, but I was quite happy I didn't have to deal with that every other hour of the day. Most people keep it short, most people keep a normal conversation volume and most of those who don't will take a hint.
And a few are the kind you want to strangle. But long before the flight was up I'd make a really loud "call" like "YES HELLO... OVER THE ATLANTIC NOW, DOING FINE. EXCEPT THERE'S THIS GUY WHO KEEPS TALKING REALLY, REALLY LOUND ON HIS CELL PHONE FOR AGES NOW, DOESN'T HAVE ANY SOCIAL ANTENNAS AT ALL. I HOPE HE HANGS UP SOON. SEE YOU SOON, LOVE YA" Fighting fire with fire usually works, if he goes psycho with luck they'll cuff him and throw him off the plane. Win-win either way.