Since there is no pre-installed instant messenger on the iPhone, you would have to download one of the apps for IM from the app store. When you use those apps wouldn't you be using some of your Data from your data plan? Correct me if I'm wrong, but the messaging plans for the iphone would only be good for text, pic, etc.
I know I somewhat answered my own question, but I just wanted to get some clarification before I decide on a phone.
I know I somewhat answered my own question, but I just wanted to get some clarification before I decide on a phone.