I was just trying out the new Ubuntu 12.04 and surprisingly, after a full update via the update center, the system just wouldn't enable my CDMA modem. However, the GSM modems were working fine. After a lot of searching in the vast resources of the internet I found the solution. It's a simple 2 line execution in the Terminal.
sudo rmmod -f iwlagn
sudo modprobe iwlagn 11n_disable=1
sudo modprobe iwlagn 11n_disable=1
Apparently, there is some problem in the system and it's not recognizing the n channels of the CDMA network, thus causing the problem. So try this if you ever get the same problem. Hopefully it will help.
Ciao!
