Upgrading AT&T phone through Apple pre-order

[iFizzgig]

I decided to test the Apple site to see what's going to happen when I pre-order my new iPhone 4S. I tested it with an iPhone 4. In any case, I indicated that the new phone would be replacing a phone on an existing account. After I did that and put the phone in my cart, it showed a voice and data plan then asked what I wanted to do for text messaging. Will these actually change my account? My current service is the family plan with 2 phones and 200 text messages on each. I don't want that to change.

- fizz