With plans for iPhone tethering in the works, AT&T apparently has already set the rates and usage limits for it. On the surface, the rates and limits seem to be in-line with what the industry likes, if not the users. By default iPhone users can expect a 5GB cap on bandwidth every month. Rather than facing overage charges, however, AT&T is apparently planning to simply cut off access once someone hits that 5GB limit – no more data.
The service will cost an additional $30/month to existing plans, which is exactly the price AT&T charges for Blackberry tethering. The biggest issue is probably going to be the bandwidth limit. If you get a standalone cell card for your computer, currently there is no bandwidth limit – why does AT&T care if you are using it through a card or using it through your phone?