Too many of us have wasted our breath explaining that your phone calls (and you know who you are) are not a public happening - they are not theater, they are not entertaining, and they are not what I want to listen to on my train ride.
Annoyed glares and subtle stares have no effect, and a polite word or two is often just just as ineffectual. But at least those of who speak up see a small percentage of success - there are many who just don't know what to say when their ears are being similarly assaulted. Finally, the aspirin for that headache is here! Coudal Partners has started the Society for HandHeld Hushing and created a handy tool for this exact situation.
Download the PDF from their site (or here, if it's more convenient), print it out, and start creating beautiful silence!