1) go to “cydia”
2) search “legacy”
3) install the first link (top one) that pops up and let the iPhone respring
4) go to “settings”
5) then “general”
6) then “network”
7) then “Cellular Data Network”
under the MMS section, the “APN” should be wap.voicestream.com
ENJOY!
**note that this will work ONLY on 3G and 3GS models. MMS count as regular text messages.