Get MMS working on iPhone 3G, iPhone 3GS, MMS on 3.1 for AT&T.
Step 1 : First of all, you have to update to 3.1.
Step 2 : Download the program 'unlockit' at unlockit.co.nz
this program will unlock the MMS and get the settings automatically to your Iphone 3Gs.
Step 3 : You have to be on an MMS plain.
Step 4 : You have to change from a DATA plan to the unlimited, 'Unlimited DATA, Unlimited MMS'. "Both cost 30$ a month".
Step 5 : Sending an MMS does stop almost at the end, but it does carry on. Just be a little patient.
Step 6 : You need a AT&T Phone.
Follow these steps and your MMS's will be sent without problems.