AT&T is informing jailbreak tetherers on grandfathered unlimited data plans that either they stop tether or sign up for 2GB tethering plan. If you don’t abide, AT&T will sign you up for a 2GB tethering plan and kill your grandfathered unlimited data plan for good.
A thorny wicket. It’s probably not fair to congest AT&T’s networks by sucking up data from your iPhone to play World of Warcraft on your MacBook Pro without, you know, paying for it, but if you’re intent on doing so, there may be a way to avoid AT&T’s scrutiny, keep tethering through your jailbroken iPhonei, and keep your unlimited data plan, all at the same time.
AppAdvice shares this great little Cydia trick: instead of using MyWi to tether, use PdaNet.
[W]hen your iPhone goes into tethering mode, it announces itself to AT&T, making it easy for them to detect you. To avoid that, the developers of PdaNet built-in a special mode to their tethering app to avoid being detected by AT&T.
The best thing about this trick is that PdaNet is free for most sites, while MyWi will cost you after a demo period, so there’s no reason not to give this a shot. It might not work — especially if you’re sucking in an ungodly amount of data through tethering — but it’s better than going meekly into that brave night.