Just saw ATT added smartphones to their prepaid Go Phone plans http://www.wireless.att.com/cell-ph...jsp?wtSlotClick=1-0050TW-0-2&_requestid=89814 My top questions, now with answers. Is it iphone compatible = YES! Does the data expire = YES If you have auto renew turned ON and you go over your data amount AND you have enough money attached to the account the data will renew automatically. If you don't have enough money in the account, you need to by more and then call in to get data restarted because once stopped it won't restart by itself. It is likely you will need a new SIM but if you want to sign up over the phone 18003310500 can do it. I needed a new SIM but I got the SIM and activation free, YMMV. Apparently out of contract ATT SIMs get disabled. Smartphone data plans for Go Phone prepaid $5 for 10 MB $15 for 100 MB $25 for 500 MB Voice is either $2 a day or $.10 a minute. In contrast ipad users pay $15 for 150 MB, so not a bad deal really IMO. Obviously not as good as the ipad 2gig $25/mo plan, but it is FAR better than the previous $75/mo unlimited/200 MB prepaid Go Phone plans. Data on the Go Phone prepay plan requires an APN. This is the best guide I found for this exact situation: http://www.theiphoneguru.net/2010/07/28/use-your-old-iphone-as-a-prepaid-go-phone/ Or simply go to http://www.unlockit.co.nz/ Add a custom APN, in drop down select “US – AT&T.” and install that profile. Edited with answers.