Data Not Working on AT&T GoPhone

I sent the below information through the contact page; but I decided to post on here as well, just in case someone else has the same problem/solution.

First off, thank you for this website! It works very well and I'm very pleased with the ease of use.

Let me briefly explain the problem we're having. I have 2 friends that live in Canada and have Canadian iPhones that were both originally locked to Rogers. Both of them have upgraded to 3.0, then I jailbroke with redsn0w and unlocked both using ultrasn0w. They went on a trip down to the States so we purchased a couple AT&T sim cards, activated using their pre-paid GoPhone service, then added money and the MediaNet data package. As of June 19th, AT&T changed their policy and, by default, no longer allow iPhone 3Gs to be used on their Pay And You Go GoPhone service. Then I found this website which changes the APN Settings on the phone to actually allow it to work on the AT&T GoPhone service.

Creating a custom profile on each phone appeared to temporarily allow data access. Once the profiles were installed, both phones could use the MediaNet data package that was on their respective accounts. Then, mysteriously, one phone is still working great while the other can no longer connect to the internet through AT&T's network. My first thought was that maybe ultrasn0w was not working correctly, but we verified that both phones can still make and receive both phone calls and text messages. But only one of them is still able to access the internet through the MediaNet data plan.

I have double checked all the settings on each phone and they both appear to be the same. I can confirm that both sim cards have the exact same packages and dollar amounts (There is money available on both phones and both data plans have not reached their limit). We deleted the custom profile on the phone that is not working and reinstalled. We've restarted the phone numerous times. It's still not working.

I'm wondering if there is any other settings that we can check or other options available to us. I have confirmed that everything is set up correctly through AT&T's automated system (both phones have at least $30 remaining and they both have the MediaNet data package added). I do not want to call into AT&T's customer support because I don't want them to know we are using this service on an iPhone; they'll most likely block any attempt to use data on this phone.

Thank you for your help!