First, go to Settings > General > Network > Cellular Data Network.
Add the following in MMS field:
- APN: wap.voicestream.com
- Username: leave blank
- Password: leave blank
- MMSC: 126.96.36.199/servlets/mms
- MMS Proxy: 188.8.131.52:8080
- MMS Max Message Size: leave blank
- MMS UA Prof URL: leave blank
Again, this only works if you have T-Mobile. It does not work with other carriers.
Feel free to contact me should you have iPhone tips and tricks you want to share.