Before you get a chance to go to settings app and turn off mobile data, the OS probably already made 10 data requests to check 20 settings. It is data call. Whether the telco should count that as data and charge for it is a different question.
And if they don't have data in the plan the carrier by default just doesn't forward the packets
AT&T (and most of the wireless industry) are merely toll-gate operators - they are very good at making sure you pay for any usage - even the usage you didn't want to make (ie, receiving an MMS on your non-data flip phone that you didn't intend - sorry, that's $2).