I recently switched to H2O Wireless (works on AT&T network). I have an ulocked phone.I wanted to access the 100 MB of Internet I get with my $40 plan. So, I tried to put my old AT&T APN settings but it did not work. I contacted the customer care and they provided me with their APN settings. I am posting them here for anyone who may need it:
To manually put in APN settings. Go to Settings > Wireless Network > Mobile Networks >Acess Point Names. Click on 'New APN' from options. Then, key in the following settings. Leave the fields blan that are not mentioned below:
APN: att.mvno
Proxy: 66.209.11.33
Port: 80
MMSC: http://mmsc.cingular.com
MMS Proxy: 66.209.11.33
MMS Port: 80
Press the Menu Key and click "Save"
Be sure to select the APN you just created from the APN list to use it.
Hope this helps
Thanks