Samsung
From Droam Prepaid SIM Encyclopedia
Samsung Galaxy Tab
Verify that you have an APN and that you have the user name and password for the APN. Check for the APN settings on our Main Page (choose country and cellular provider)
Go to Menu > Settings > Wireless & Networks > Mobile Networks > Access Point Names
Samsung Galaxy S
1 - Press the "Settings" button on the menu.
2 - Press "Wireless & networks".
3 - Press "Mobile Networks".
4 - In this screen, enable the "Data Roaming" option and press "Access Point Names".
5 - Press the menu button on your phone and choose the "New APN" option.
6 - Press "APN".
7 - In the pop up window enter : 1234.1234.12.12 in the text field and press "OK".
8 - Now press the "Name" option.
9 - In this text field enter a name (APNChangeR for example). Press "OK".
10 - Press the APN Type and choose the "Default" option (In version 3 choose "Internet").
11 - Now you just need to choose the APN you created and you can start using the internet!