After putting the ipcc file using instructions from
here
Here are the steps I used to provision mms on my phone with out calling ATT. I didn't change anything online fro my plan like step 5 says to do and my iphone can mms all day but that's probably because I have a family plan with unlimited messaging.
I stole some of this from swirlymms blog post.
"1. First, you will need a regular AT&T/Cingular phone. I used a old Samsung A737. You should be able to use any phone as long as it is Media Net compatible.
2. Take the SIM from your iPhone, Insert it in to a standard phone, Make a phone call, wait about 5 minutes.
3. After 5 minutes go to the following link,
My MEdia Net
Enter in your mobile number(it might say your phone is not supported.. if so wait a little longer and try again), then at the next screen it will ask for a 4 digit code.
The 4 digit code will be sent to your phone via Text message.
Enter the code in on the website and then you should be able to access the main Media Net site.
4. Now send a mms. I also made some calls and called my number from another phone. It will take some time for the network to recognize the phone. Be patient. Took me about 10 minutes.
5. If that worked and it sent a MMS great and skip this step. Otherwise, log into att wireless at
https://www.wireless.att.com/ and you should notice your phone your using to make this work is now listed as your phone/device on the account overview page.
Click on the manage features on the right side of the screen and scroll down to messaging and change from whatever it was (mine was iPhone Text Messaging Unlimited) and change it to "Messaging Unlimited
AT&T Recommends" (i guess they recommend it because your aren't currently on your iPhone).
You should be able to stay on the "Data Plan for iPhone 3G" and not make any changes to that part as I didn't. If you change this, I think this is where I lost my Visual Voicemal.
Wait a few minutes and your MMS should finally make it through on your temp phone. If not this might not work for you.
6. Now take out the sim card and place it back in the iPhone.
Here is a link to a screenshot of my phone sending and receiving mms
HERE