Is it possible to buy a iphone that is not under contract but has been activated then buy a crappy phone from at&t that has a 3g sim card and put that sim card into the iphone and escape the monthly $120 bill and it still function properly?
you can...buddy of mine just did that...but if you dont have data plan...then you can only access thru WIFI for free...and when you are not on WIFI..and if you mess around with Edge..it will cost you...so becareful. If you can jailbreak it, then download BossPrefs app and disable EDGE.
If you already have data plan on your old phone...you can go ahead and use EDGE, but not for long...ATT will know and will send you a text message to warn you about it.