periodic GPRS network activity - what is it??

[Guest venutia]

I'm trying to do an AT&T pay-as-you-go plan with my blackjack2 ("go phone"). I've discovered that something is using the network and racking up all these tiny charges at all times of day and night. I'm not sure that I have any way to figure out what the activity is and how to put an end to it.

Now granted, every networked device has some activity to maintain its existence on the network, but it's quite a small amount of data. I had the minimum 5mb plan for emergencies, and that's already used up. An AT&T CSR claims that they're "updates", but she couldn't tell me what was being updated or why it was necessary.

The phone has always woken itself up periodically and used the network, and I've never understood what it was doing. It makes me uneasy.