I assume it only uses data when you ask it to find something on the internet, the same as if you do it. The voice translation is all done in the phone. If you ask it to do something that requires data it should just translate the voice to the same data commands that would come from the keyboard or touchscreen.
anyone have any idea how much data siri uses over 3g??
Saw an article on this very topic earlier today by ArsTechnica and hope it helps backinblack
http://arstechnica.com/apple/news/2...tm_source=rss&utm_medium=rss&utm_campaign=rss
"If you use Siri 2-3 times per day at an average of 63KB per instance, you might expect to use 126KB to 189KB per day, or 3.7 to 5.5MB per month.
"For 4-6 times a day, that might come out to 252KB to 378KB per day, or 7.4 to 11MB per month."
"If you use it 10-15 times per day, you might end up using 630KB to 945KB per day, or 18.5 to 27.7MB per month."
Try using Siri with all your data connections off. It will still work but will not be able to get any data from the internet. You are not connecting to some external server to talk to Siri. It's on your phone. It's just a voice control of your phone. If you ask Siri to search something it will go on the internet and find the info just as if you typed it in a search.