Can I get MMS on my iPhone without firmware 3.1 (with firmware 3.0)?
The answer is yes. International users already know this fact. In the US, you can update the AT&T carrier file to version 5.5 without updating your iPhone to firmware 3.1.
There are reasons not to update to iPhone OS 3.1. Many users are complaining about decreased battery life and other problems. Here's how to get MMS on your 3G or 3GS without updating the firmware.
1. Right-click to download the new carrier file (ATT_US.ipcc) that activates MMS. You can find this file at one of the two links below:http://dl.getdropbox.com/u/29849/ATT_US.ipcc
2. Close iTunes.
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3. On a Mac, open a terminal window by clicking Applications -> Utilities -> Terminal. Type or paste the following command followed by the return key: defaults write com.apple.iTunes carrier-testing -bool TRUE
On a Windows machine, open a command prompt by clicking Programs -> Accessories -> Command Prompt. Type or paste the following command followed by the enter key: "C:\Program Files\iTunes\iTunes.exe" /setPrefInt carrier-testing 1
4. Run iTunes.
5. Connect your iPhone to the computer with the USB connector.
6. Make sure your iPhone is selected in iTunes. On a Mac, hold down the option key and click the Check for Update button in iTunes. On a Windows machine, hold down the shift key and click the Check for Update button in iTunes.
7. A window will appear to browse files. Make sure the file type is set to carrier file (.ipcc) and choose the ATT_US.ipcc file you downloaded. The update will install.
8. Close iTunes and reboot your iPhone.
MMS should now be working on AT&T with firmware 3.0. To check that the correct AT&T carrier file was installed, touch Settings -> General -> About. Next to Carrier your iPhone should say AT&T 5.5.