How to voice activate an iPhone without touching it? Illinois' law states cell phone use must be hands free. I realize they intend for you to use a hands-free kit. How come when, at least when it rings, I can't tell Siri to answer it onto speaker phone? Why isn't she listening for commands like the star ship Enterprise?
Get an iPhone case that provides backup power.
You can maneuver iPhone completely hands-free by saying "Hey Siri" if you are willing to keep your phone plugged in to a portable USB battery while you walk around.
iOS 8 has "Hey Siri" built-in:
Settings > General > Siri > "Hey Siri" > Enabled
The rub: "Hey Siri" only listens when phone is plugged in to power.
The fix: Bring a portable USB backup battery and keep your phone plugged in!
Some protective iPhone cases also have built-in batteries you can use to charge your iPhone when the time comes. I imagine this would be the most convenient way to accomplish what you would like to do without having to carry extra items.
I asked around the Genius Bar at an Apple Store in Chicago why they suppose such a feature would have such a restriction, and the general consensus suggested was that people in close proximity would likely set off each other's phones. My personal suspicion is that constantly polling in the background might be costly in terms both of battery life as well as network traffic, and most people plug in where WiFi is much more likely to be available.
I figured Siri would recognize our voices by now! =)