Originally Posted by Marciexyz
Exchange sync uses different protocols - been a while, can't recall which (RPC over HTTPS maybe, plus some used in maintaining heartbeat with the Exchange server). AT&T can see the different traffic types and slap data overage charges on for traffic that is not within the accepted data types."
You are correct Exchange does use RPC (remote procedure calls) over HTTPS, if it is configured on exchange server/IIS side (microsoft webserver). ATT has no control over this, it is a standard feature of current Exchange release. It is the same setup that is used for Palm phones etc. It does use a heartbeat and some can say it is truely not pure push technology. That heartbeat is what eats the battery life on all phones that are set for mail to be delivered when it arrives at exchange.
Because it is using HTTPs, and therefor encrypted, there is no way for AT&T to determine what is being sent to and from exchange. All they can see is HTTPs traffic to a webserver.
Now on the iphone side, if they wanted, and looks like they are not doing it. Also its smacks of big brother so doubtful they would even try. They could technically track it based on the webmail app, since you must configure it as an exchange account and somehow report back to AT&T when it is being used. This would still not be definitive proof of business use since there are personal exchange servers.
Forgot to add, yes they could disable firmware support for exchange based on activation codes etc. But I would bet that would be cracked sooner then someone unlocking or jailbraking a new iphone firmware release