Did you set up an online account? If so, open your web browser on your computer and go to
www.att.com and log in. Once you do, your usage and billing info should show up (you may have to get through a promotional screen or 2 first).
If you didn't set up an online account, you'll need to do that first. I can't remember for sure, but I think your account number should be on the paperwork that came with the Mobley (assuming you ordered it directly from AT&T). You'll need that to set up the online account. If you need help, online chat is available.