Does that mean ATT can not detect it from your understanding?
As far as I can think... I don't think so. But it depends on what the traffic looks like that is coming out of the App...
Also, like I mentioned earlier... the fact that it is phoning home is kind of giving you away ;-)
However, a better question is whether or not this is actually against ATT policy at all. This is just an App that is talking to the internet... that's obviously not against policy.... and _happens_ to also send and receive data over the USB port (that's also not against policy).
Here's a thinker for you: If I make an app that sits around all day waiting for an email to come in... and when it does it is supposed to download a file that is sent as a link in that email and then push that file down the USB port to my computer. If I send an email to that app (well, to a server that that App is looking at) from that same computer... I have just initiated a download from the internet to my computer _through_ the phone.
Is that against ATT policy?
How would you draw the line? Legally, where is that line? I think it's hard to say.
It's obvious that ATT is against your phone running as a wifi hotspot while using 3G data without paying them extra cash. But that's not what's happening here. We're just communicating with an App that happens to simultaneously be communicating with the internet...