No MMS, internet on T-Mobile Note 2

Is there a question here, or do you want help?  Or just venting?

You need to manually enter the AT&T APN info into Settings, in order to get data service on the network.

Also, depending on what band support your device has, you may not get HSPA and/or LTE on AT&T's network, and be limited to EDGE (2G) data speed.