Actually AT&T did release the OS4.5 Igot it after I downloaded the 4.6 desktop manager software to my computer and I plugged my Curve 8310 up to back it up and before I could back it up I got a pop up telling me there was updates for my phone and low and behold it was 4.5!!! I don't understand why they don't have it on thier site, but when I called AT&T the did confirm that it had been released awhile ago, and that they were one of the very last onesalso qui to release it. So I would say download the latest Desktop Manager (currently is 4.7)from the blackberry site click here** I hope this helps everyone with AT&T let me know if this works for ya'll as it did for me please.