Why AT&T Doesn't Support Tethering
Because their network can't handle the load. That's the reason according to a Macblogz source that is currently working for AT&T.
According to a previous rumor Apple and AT&T have been working together to build an iPhone tethering plan similar to the one Blackberry users currently have on the AT&T network. It is said that due to AT&T's parinoia of "legalities" that could occur from iPhone tethering on its already overloaded 3g network this iPhone tethering plan has not been implemented.
AT&T is worried that their already flimsy 3g network will not be able to handle any additional strain caused by iPhone tethering and users will create lawsuits against AT&T. This fear is not with out basis. There are already lawsuits filled against AT&T because their 3g network hasn't been strong enough to handle the iPhone 3g without tethering. If they were to add a tethering plan and the network subsequently failed they would undoubtedly have to deal with additional lawsuits.
The fix would be to spend more money on the network and make it able to handle more load but according to the source “Regardless of how many billions of dollars AT&T pours into their 3G network, it hasn’t been stable enough to handle all you iPhone users."
There is light at the end of the tethering tunnel. AT&T does appear to have plans to strengthen the network and release and iPhone tethering plan some time in the future. Of course why wait? We can already tether just fine
thanks to some great Cydia apps.
[macblogz via electronista]