Just as a reference. I USE At&t VV and tether through a custom rom and also used Foxfi before on stock rom. Have yet to receive the tethering message. I don't use it for downloading gbs of data though but have been tethered for 5 hours non stop.
Sent from the Millennium Falcon
I use Foxfi and I have never recieved a warning. But the amount of usage differs each month on when they throttle me back. sometimes 2gb sometimes 5gb. I give up. I just use it until it goes slow.