Demandarin said:
Not really...all cell phones companies gonna follow this suit. Just like AT&T was the first to stop unlimited data plans(glad I'm grandfathered in and still have it), other major companies followed the same path. People shoulda known this was coming so it's not really news to me. Plus anyway, the only way theyngonna catch people is if the person is tethering like crazy. They can detect the major spike in data usage. But if u only use it when going out occasionally, every now and then, or in emergency situations, there will be no way of knowing. Especially if the person has been known for a long time to use a lot of data. Account history will show that. Plus it could be disputed also so it's really a fail on AT&T to try to scare people into paying even more cash. Not here ;-)
The reason AT&T knows that someone is tethering their connection is that every mobile device connection sends it's IMEI along.
All AT&T, or any other provider for that matter have to do is run an automated script to check whether more than 1 IMEI shows up for any 3G contract in their logs. Remember that you had to give AT&T your IMEI when you signed up? So if any other one shows up, the mobile provider immediately knows that you are tethering.