In order to make sure that AT&T smartphone users have a similarly priced bill every month with no surprises, the carrier is requiring that anyone purchasing a new smartphone on or after September 6th, must also spring for a smartphone data plan. Those who bought such a device prior to the 6th and currently owns a non-smartphone data plan will be grandfathered in and will not have to update their service plan. On the other hand, if you currently use a featurephone with a data plan and you upgrade to a smartphone on or after September 6th, you will not be able to keep your current MediaNet plan. This total package of rules applies to those who purchased their smartphone from AT&T or an authorized dealer. A copy of an internal e-mail sent to reps can be viewed at the source link. And let's face it, a vast majority of those who buy a smartphone do sign up for a smartphone data plan, so you should not be able to notice any changes.