I got the same message.
I bought an iPhone 5 at full retail price from an AT&T store. I requested the phone to be unlocked through their unlock portal. The AT&T unlock system asked for the IMEI number, a copy of my receipt showing that I bougth the phone at "No Commitment" price. A few hours later I received a message from AT&T stating that the unlock request was approved. I then followed the instructions to back up the phone and restore it through Itunes. The phone activates normally with the AT&T SIM card. But when I insert my VODAFONE SIM I get the massage "THE SIM CARD... etc.
I tried again to back up & restore the phone 3 or 4 times, no success. I have also allowed 24 hours for the unlock process to complete. Still no luck.
I have checked again on the AT&T Unlock Status portal and it shows "Unlock approved".
Where is the issue here? Do I have to call Apple or return the phone to AT&T and get the unlocked phone through the Apple Store?
Thanks for any help on this.
To add on top of my previous post, I have tested my Italian SIM on another unlocked iphone I have and it works fine: phone boots up, and I get the usual warning messages regarding roaming, etc, and the phone hooks onto AT&T or T-Mobile as the case may be.
The problem is in this new phone itself.
Any suggestions or hints are appreciated, thanks again for any help on this.
If you go through this discussion it may help you understanding. Even after approval of the unlock by the Carrier, the unlock could get attached via iTunes after more than a fortnight.
Guess you can't help but be patient with Apple Servers to respond appropriately.