Here's an update. I purchased this phone from Amazon off contract for $449. I don't know if i had to unlock it, but i handed it to a nice fellow at an ATT store and asked him to put in a compatible gophone microsim and to make it use my existing gophone account. He slipped in the microsim and did some config work and made some calls to a support line, but not sure if 'unlocking' was one of the steps. (sorry, wish i could tell you what all that was).
Not 100% what MMS is, but i think it's not working. I took a pic and then tried to send it using the WP7 "Messaging" facility. It kept responding with "Can't send message, Try again" I could use this same Messaging thingy to send a text-only message.
A few more items....
My firmware version is: 2175.1022.8112.12084
I don't know where else to check on what kind of speeds i'm getting, but the little note at the top of the screen next to the signal bars is saying 4G. I live in a place where ATT does not support LTE, so i must be tapping into some other 4G flavor. Sorry, i wish i knew more about this. If you can tell me where to look on the phone for more info, i'll report back.
First, to get the data to work, i had to add an APN (i subsequently removed it, and it seems to be a necessary step). I found these settings on some other thread:
1. Go to Settings
2. Select Cellular
3. Click Add APN (will read Edit APN if you've already got one!)
4. APN: wap.cingular
5. User name: firstname.lastname@example.org
6. Password: cingular1
since i update to the new build (12084) GPS is not working properly. I don't see anyone else having this problem, and i've logged a support request to nokia. looks like they aren't open until Monday.