Connect to the internet via an UMTS connection using Ubuntu 11.10
From LinuxIntro
When Ubuntu starts up it asks you for the PIN of your UMTS card. Enter it to unlock the card. Next, click on the NetworkManager icon in the upper right, it looks like this: 
. Then click on "New GSM mobile broadband connection" -> choose your country (in this case Germany) -> choose your carrier (in this case T-Mobile) -> ok
You see how NetworkManager's icon turns into a connectivity status 
and internet works.
