Wrong numbers

I've had a cell phone in China for the last five months. I tried to not get one, but it is an evil necessity sometimes.
The problem with cell phones in China is that they recycle numbers rather quickly if a consumer doesn't pay the fees to keep said number. It seems all phones are just pay as you go. This leads to far too many wrong numbers (or maybe sales calls, I'm not sure).
I speak a little Chinese, but I'm not very good. I never quite know what to say when people call constantly. I used to just not answer, but that led to continued dialing from the other party. Then I tried just hanging up. It usually got the point across. But I get tired of it all.
I answer my phone in English with a "Hello" or "Yes." This is followed by the other party babbling beyond my comprehension in Chinese. It is at this time that I usually say politely, "I don't speak Chinese." And the other party continues to talk. I repeat, they talk. Finally, I get fed up and shout into the tiny electronic phone that never seems to work properly, "I DON'T SPEAK CHINESE!" And the other party hangs up immediately.
Now, I just wish it were that easy to get rid of the persistent shopkeepers who harass everyone with the same knock-off product as every other shop in the market.