Re: Modify handset ?
> It T-Mob is so incompetent they don't have proper billing and traffic accounting on server side they deserve to be taken for a ride.
> Edit - apparently all you need is to install third party wifi tethering app. Wow.
I'd imagine they actually do have proper billing and accounting. What Android does currently (and I assume iOS does too) is to tag data flowing through it with a "tethered" flag (I believe this is a relatively newish feature, and I suppose you could also bypass it with a very old Android version). That way an operator can detect the fact that the data is from a tethered source. You have to explicitly modify the OS behaviour to remove this tag, and then the network cannot distinguish between the two sources/sinks of data (phone or tethered computer) - they just look like plain old IP packets.
Not sure if you need a rooted phone to modify the flag - I suspect you do. But as you can get something like a half a dozen users consuming a huge chunk of network bandwidth due to such greedy behaviour, it's hardly surprising that they're being targeted for this attitude. It is, after all, quite clear from the ToS that they are abusing the service outside of their contractual bounds. Having to spend money to install servers to allow a single user to d/l 2TB of data in a month (which is equivalent to (hopefully my maths skills are correct!) 6 mbits/sec continuous use 24/7) must be quite irksome