try putting in a friend's sim card that also has AT&T, i may then automatically push the proper settings/service books to your phone. before i didnt have any of them as well, but after i swap sim cards with my brother's regular dumbphone and put his sim into my BB, it pushed over all of the media mall stuff as well as MMS client stuff. then i just put my sim back in and good to go. also check your TCP/IP APN settings, change it to AT&Ts.
I've actually done the opposite.
I bought an AT&T phone, unlocked it, and used it on T-Mobile.
They told me that just because it's an unlocked phone, it doesn't guarantee that the phone is COMPLETELY compatible... because it was made especially for a specific server.
So... I went without sending picture texts when I had the AT&T phone.
I also bought a locked to T-Mobile 8220 and unlocked it (I have AT&T)...after several hours on the phone with AT&T they told me they couldn't help me...what I finally ended up doing was updating my OS. I first tried 180...that didn't work...when I was done with that I had no MMS options at all! So I updated to 4.6.0.200 and finally got it to work! Good Luck!
I also bought a locked to T-Mobile 8220 and unlocked it (I have AT&T)...after several hours on the phone with AT&T they told me they couldn't help me...what I finally ended up doing was updating my OS. I first tried 180...that didn't work...when I was done with that I had no MMS options at all! So I updated to 4.6.0.200 and finally got it to work! Good Luck!
Thank you for this. that's how I got mine to work TODAY!!!! I got the run around yesturday. from ATT ->BB ->Tmo ->BB -> ATT-> BB->ATT. I paid that $50 charge to fix 1 problem with RIM and that was probably the worst idea I have ever had. to all, RIM is just as clueless as the carriers. they were of NO HELP!!!