In the 3.1 update the MMS and tethering hack did no longer work, although some people reported that the hacks were still working for them after the update. Aaron Krill, the man who discovered the hacks, is back again but with just the tethering hack. Bellow are the instructions on how to do it, the hack only works for At&t.
First make sure you have iTunes 8.2 or 9, your iPhone is running OS 3.1 and you have the modified version of the At&t carrier file “ATT_US.ipcc” download the file here.
You must enable IPCC updates on iTunes with these steps:
1. Make sure iTunes is closed then open up Terminal Open Terminal. Applications > Utilities > Terminal
2. Paste everything bellow into the box:
defaults write com.apple.iTunes carrier-testing -bool TRUE.
1. Make sure iTunes is closed,then go to start> run> and type in the box CMD
2. Paste everything bellow in to the box, by right clicking on the box and hit enter.(shortcuts wont work):
“%Program Files%\iTunes\iTunes.exe” /setPrefInt carrier-testing 1
Now you must update the carrier file with these instructions:
Open up iTunes and connect your iPhone.
Click on your iPhone in iTunes.
Windows: hold shift and click Check for Update.
MAC: hold alt/option and click Check for Update.
Select the ATT_US.ipcc you downloaded earlier.
Once everything looks clear reboot your iPhone.
MMS should be enabled.
It is not guaranteed that this will work because At&t is well basically fiddling about with it right now.
Here’s Aaron Krills blog