Hmm, I finally got it to work for mine. It's showing up using my Order Number and zip code. HOWEVER, it is my OLD zip code, as I changed my address when I ordered over the phone. Apparently that didn't actually happen in the ATT system (even though they MANUALLY did it). If you recently changed your address, try the old zip code. Order number + old zip and I got confirmation that there is a package, but no actual tracking info yet.
First post here. Signed up after trying the track by reference with my old zip code and it WORKED!
But get this. I both made and cancelled this order on Friday because it was gonna be shipped to the wrong address, and AT&T is STILL shipping it!