Hey guys - I had this same problem. As the last guy posted, this problem has been solved! I had a great experience with AT&T dealing with this. The solution is on my blog:
http://www.mylifestartingup.com/2008/12/iphone-we-were-not-able-to-validate.html
Yes, make sure that they have the correct model in their databases.
After reading this, I asked that question several times and was told yes.
I'm on support right now and I was told that it was showing up as my old Sliver.
My ATT Wireless page had been showing that and I fixed it last night. I guess they don't trust what I put in...
I'll update later whether this works or not.
Okay, it turns out my IMEI # was also showing up as invalid.
I went through:
Customer Service -> tried to send me to Apple
-> sent me to Technical Support
Asked specifically about my model and IMEI and was told they were fine
As a plus, Tim (my tech) did call me back 10 minutes later and sent me to:
-> sent me to Advanced Networking
This tech immediately said I was in the wrong place and she was going to transfer me
She then informed me I had the wrong model listed in some database and was going to transfer me
(on hold)
She then informed me that me IMEI was wrong
(on hold)
Had me register at
http://www.wireless.att.com/medianet
Told me it would take 4 hours
So, thanks Roselle!
I'll update in 4 hours...