iPhone 2G supports MMS using cellular data over GPRS/EDGE, though Apple never enabled this in any of the firmware. This guide will show how you can enable MMS on iPhone 2G Firmware 3.1.2 or any other version.
Step 1. Add Cydia source http://cydia.ifoneguide.nl if it isn’t already added.
Step 2. Search for Native MMS iPhone 2G and install it
Step 3. Restart your iPhone. You should now have MMS features. Navigate to your Messaging app, and camera button will appear. To start sending MMS, you will have to set your carrier settings for MMS in:
Settings –> General –> Network –> Cellular Data Network
That’s all, you are Done!