Welcome! I understand you need help setting up T-Mobile MMS settings for an AT&T® Samsung Mythic (A897).
I have a document straight from AT&T that may answer your question on configuration. Click here to access it.
Unfortunately that does not help me. What I need to know is what to enter into the MMS messaging settings for the phone to work with T-Mobile's MMS servers so that I can send photo messages. That site shows configuration for MMS for AT&T, and it doesn't give the full info at that.
Thank you for trying though!
We definitely want to make sure you get those settings. We have them available in our Generic handset settings for Internet and picture messaging (MMS): Non T-Mobile document.
Thanks for joining the Community!