To all who are still trying to get MMS on iOS 4 working. I finally got MMS working on my iPhone 3G using the following method and settings:
I jailbroke using redsnow 0.95.5b5-5.
I unlocked using ultrasnow in Cydia.
I installed the T-Mobile 4.0 MMS Fix in Cydia from the following repository,
http://beta.leimobile.com/repo/Lastly, I am using the following settings:
Enable 3G: Off
Cellular Data: On
Data Roaming: On
Internet Tethering: Off
Cellular Data
APN: internet2.voicestream.com
username:
Password:
MMS
APN: wap.voicestream.com
username:
password:
MMSC:
http://mms.msg.eng-t-mobile.com/mms/wapencMMS Proxy: 216.155.165.50:8080
MMS Max Message Size: 1048576
MMS UA Prof URL:
http://www.apple.com/mms/uaprof.rdfInternet Tethering
APN:
Username:
Password:
Hope this helps everyone that was in the same boat as me.