Enable MMS for AT&T/Cingular on an Unlocked myTouch 3g/HTC Magic/Google Ion

I had some trouble setting up my Google Ion (with Cupcake 1.5) to send and receive MMS messages. I could connect to the Edge network, browse the web, use the Market, etc. But something was wrong with my settings and I couldn't send or receive picture messages. I spent some time searching through forums, reading posts that were nearly identical in content. In general, the settings were similar to the ones I've listed. Each one had slight differences in spelling, capitalization, and punctuation. These can be pretty important differences at times, so pay close attention to the exact value that you type into your phone.

Below are the settings that I used that have successfully connected me to the Edge network and enabled sending and receiving MMS/Picture messages along with the normal data functions like browser, gmail, market. To my knowledge, these should work for any AT&T customer.

1. Go to: Menu->Settings->Wireless controls->Mobile Networks->Access Point Names
2. Add a new APN (Access Point Name): Menu->New APN
3. Now fill in these values:
   
   
   Name: AT&T
   APN: wap.cingular
   Proxy: <Not Set>
   Port: <Not Set>
   Username: <Not Set>
   Password: <Not Set>
   Server: <Not Set>
   MMSC: http://mmsc.cingular.com
   MMS proxy: wireless.cingular.com
   MMS port: 80
   MCC: 310
   MNC: 410
   APN type: <Not Set>
   
   
   
4. Save your settings: Menu->Save
5. Power cycle your phone (turn it off completely, then turn it back on). This is to ensure that the new settings are used. At this point, you can try sending an MMS message to yourself, and it should work!
   

Note: If you are still having trouble after using the above settings, try adding these two values in all caps:

Username: WAP@CINGULARGPRS.COM
Password: CINGULAR1