Hi all, I am not sure if someone has posted this solution yet. Like many people that have JB/Ultrasn0w their iPhone 4, they can't seem to be able to get their MMS working, since there are no APN setting for you to change. I've done searchs online, forums but can't seem to find a complete instructions to get the APN settings. Finally i found out what was the main problem by accident. so i am posting this here to help others that have the same issues. here are the steps to take, from a fresh start 1. Restore your iPhone from iTune with 4.0.1 2. open safari, go to jailbreakme.com, to JB your phone Make sure you go into cydia to update all the settings. 3. after JB, go to cydia and install Ultrasn0w to unlock your phone 4. after you have unlocked with Ultrasn0w, turn off your iPhone. 5. take out the sim(AT&T), and turn on the phone with no sim inside. 6. after the phone is on, reset your network setting. 7. insert the T-mobile (or any other sim), while the phone is on. 8. there should be a message pops up tell you that you might get billed for facetime call , blah blah. 9. go to network setting, and you'll find the APN network setting in there. here is the setting for T-mobile (USA) network, for the mms to work. go to "settings" -> "General" -> "Network" -> "Cellular Data Network" Cellular Data APN: wap.voicestream.com MMS APN: wap.voicestream.com MMSC: 22.214.171.124/servlets/mms MMS Proxy: 126.96.36.199:8080 leave everything else blank. that's it!!! now you can send MMS in a none AT&T network.