If you recently unlocked your iPhone 4 and tried to run it on a T-Mobile US SIM, you must have noticed that MMS doesn’t work anymore. Well good news is that there is now a fix available in Cydia which will fix this problem once and for all.
Simply follow the instructions posted below to fix MMS issue on unlocked iPhone on T-Mobile US running on iOS 4.0.1 / 4.0.
NOTE: You will need to have a jailbroken iPhone to get it to work. Follow the step by step guideposted here to jailbreak your iphone 4 , 3GS and 3G on iOS 4.0.1. Instructions for unlocking iPhone 4 can be found here, and for iphone 3gs and 3G can be found here.