Originally Posted by photonsnake
The text said the following: SprintFreeMsg: Recently we noticed usage on your account that is not allowed by our terms and conditions. Please call 855-235-8851 for more details. Also got a letter saying the same thing. Anyway to modify the APN?
If you used the first version of the hotspot mod it would have made changes to your APN, but it had to be reflashed every time a PRL update happenings. I suspect that they could have caught on to the way the first version worked, which version did you use?
I suspect that the first version may have made tethering traffic look different from their side because of the way it worked and the default iptables rules on your device. If you did not use the first version of the mod then it may be just because of the torrents you mentioned. When I was on Verizon torrents would start to download and then just stop, so I do think carriers can notice torrent traffic. That message wasn't very descriptive, so it very well could be sprints version of an MPAA warning, meaning you pulled something that was a trap. But also it could just be because it was torrent traffic in general.
You don't seem too concerned about having to switch carriers if necessary, maybe use the latest hotspot mod for your phone and skip the torrents for a while to see what happens.