You must have noticed that after unlocking iPhone 4 when you tried to run T-Mobile US SIM, the MMS doesn’t work. Now a fix is available for that in Cydia which will fix this problem. Simply follow the instructions posted below to fix MMS issue on unlocked iPhone on T-Mobile US running iOS 4.0.1 or iOS 4.0.
1. Start “Cydia” on your iPhone. Touch on “Manage” tab and touch on “Sources” as shown in the Screenshot below.
2. Touch on “Edit” and then on “Add” and enter url “http://cydia.pushfix.info” and touch on “Add Source” to add this repo if you haven’t already.
Cydia will now automatically update your sources by following a series of automated steps.
3. After installation search for “T-Mobile US MMS Fix for iOS4” in Cydia and install this application.
4. Now navigate to Settings > General > Network > Cellular Data Network and verify that you have the following settings for MMS or not.
MMS Proxy: 18.104.22.168:8080
MMS Max Message Size: 1048576
MMS UA Prof URL: http://www.apple.com/mms/uaprof.rdf
5. Now restart your iPhone and see MMS should now be working on your jailbroken and unlocked iPhone on T-Mobile US.[via]