Help with Unlocked Phone on AT&T Wireless

I recently bought a Samsung SGH-D520 phone overseas (unlocked) and am still under an AT&T WS contract. I set up the phone with Cingular's help and everything works except for internet access and MMS. This phone isn't available in the US at all and I can't find any support for it anywhere here as a result. While Cingular gave me the inputs to configure the internet and MMS properly, they couldn't be sure that it was right since they don't support that phone; it turns out, they weren't. I either get communication errors or DNS errors when I try to access the internet. I was told to enter in these specs: profile name = AWS, home page = http://home, security = secure (there was no place for me to enter this), IP address = 10.250.250.250 (I entered this under the proxy tab which I checked), bearer type = GPRS and APN = proxy. There are also inputs available for DNS on my phone, to check it or not, and, if checked, to enter in what appears to be similar to an IP address. Any help is appreciated. Thank you!

 

I can't accurately express how grateful I am! This is the gist of it though: Thank you, thank you, thank you!