I only tether when I'm traveling, as I have wifi everywhere I go in my normal day to day life. If I use AT&T's app to turn on tethering before I leave on a trip, and turn it off again when I get home, will the extra $20 charge be pro-rated for the time I'm on my trip? For a weekend trip (say, three days) that comes out to about $2-$3 which isn't bad at all, and I can get online as needed. My tethering is very light usage so I'm not too worried about the 2GB cap. Has anyone tried this? Are there extra charges or caveats? I'm traveling over near years and am thinking of attempting it but would love to hear if it's worked for anyone else first.