If you are looking to update your device to iOS 5.01, visit here
T-Mobile MMS - Still working From iOS 4.2.1 to 5.01
1. Use a FTP Client, and FTP into the phone
2. Navigate to " /var/mobile/Library/Preferences/ "
3. Drop "com.apple.mms_override" in that directory, and overwrite the file in there.
4. Reboot your phone, and double check the settings (Settings > General > Networks > Cellular Data Network)
5. They should read as follows, if they say otherwise just update the fields
***Note: If this configuration doesn't work, try switching "epc.tmobile.com" to "wap.voicestream.com"
If you do not have a data plan
Originally Posted by judyski
I have tried all your suggestions to get my T-Mobile MMS to work. The ONLY solution that worked for me is http://modmyi.com/forums/t-mobile/79...-settings.html
T-Mobile customer support instructed me to leave data roaming on and cellular data off if you don't have a data plan. When data roaming is enabled it increases range to pick up more "shared" cell towers.