This should probably be moved to the General Discussion forum. I haven't had Cingular in a while but I doubt they've changed their plan much.

SMS messaging is not included in the Blackberry Data package, it is a separate addon. There isn't a native IM program with Cingular, you can download Blackberry Messenger but that only allows you to IM another Blackberry. Blackberry Messenger uses PIN messaging and that is included in the data plan with Cingular.

There are IM third party programs, most use GPRS, and that wuld be included in your data package. Some use SMS and that would charge you one test message for each IM message sent and received.

Regards-Michael G.