The following are the set of simple steps I have taken to connect to the internet using SGH-i550 via 3g on Fedora 11. I would assume that these steps will also work with other brands/models and most 3g modems around.
- Connect 3g phone/modem to the computer
- Right-Click on the NetworkManager Applet and select "Edit Connections"

- Select "Mobile Broadband" tab

- Select the 3g Device from the drop down list and click "Forward"

- Select the Country and click "Forward"

- Select a Provider and click "Forward"

- Select a Plan and click "Forward"

- Confirm the details and click "Apply"

- Leave the preset defaults and click "Apply"

- Close the Connection Settings Dialogue

- Right-Click on the NetworkManager Applet again and select the newly created connection

- The NetworkManager Applet will change its icon indicating a successful connection has been established

- And you are done.
