Smoke Generators

So, I'm into pyrotechnics, and I've had this really stupid idea for a long time. Attach a smoke generator to a weather balloon and drop it to leave a trail of smoke just for the lulz. Now, I could just light it and have it leave a downward opening parabola, but I want a line. Next possibility, timer controlled trigger. I guess that it would work, but there are so many variables that it's not worth trying to calculate what time to set if I want it to go off at a specific place. Final possibility, use a remote trigger like this. Go read the post and accompanying link than come back...............done? good. If you read the comments, you'll have seen that some think about the possibility of accidental trigger. You'll also notice that some have come up with the solution of using a DTMF tone (that sound your phone makes when you press numbers) decoder to authenticate the identity of the trigger-er. So my idea about how a system like this would work is this. Set the phone to auto answer calls. Hook an arduino up to the headset port of the phone. Than program the arduino to trigger the smoke after it "hears" the code. So in step by step form, here's how this idea should play out.
1. Release weather balloon carring smoke generator and arduino/cellphone triggering system.
2. When it's time to smoke, call phone and punch in trigger code.
3. Stand back and watch in awe as a trail of smoke falls from your balloon.
4. ????
5. Profit!

EDIT: If you use Firefox, the Hyper BK plugin, and you're using a mac, use safari to post with. HBK raises hell with the html code for links in your post.