I futzed with this for hours tonight and came across a magical, simple solution to setting this up. It was much simpler than the tutorial put together by Sprint, which has you installing kppp and doing a little dance.
I did follow the instructions in the first part of Sprint's tutorial, though. I typed this in the terminal:
sudo modprobe usbserial vendor=0x1199 product=0x120
which is the string for the Sierra Wirless 595U USB modem. Each modem has different settings which are in the PDF supplied by Sprint.
Then, I typed
sudo dmesg|grep -i ttyUSB
to confirm the modem was detected. After doing a whole runaround with kppp like the Sprint manual insisted, I failed over and over and rebooted.
When I rebooted, I attempted to run the modprobe command again, but was told that the port was already in use. Sure enough, running the dmesg command reported my Sierra Wireless modem was online at /dev/ttyUSB0.
Now, what I did to finally make it work. I right clicked on the network panel, then edit connections.
I added a new mobile broadband connection (doesn't matter what you name it)
Under number, enter #777, and "user" for both username and password. You shouldn't need to change any other settings.
I then left clicked on the network panel icon, selected "auto mobile broadband connection" and voila, I was online.
I'm going to reboot and try this again to see if it continues to work - this is my first go but wanted to share my success. Hopefully it will help others get online too!
Just because it kind of goes along with the OT, I am running cruncheee on my eeePC 901 and what baffled me tremendously, considering that I went through hell and high water getting my Sprint/Sierra Compass 597 USB modem to work in gOS 3.1, was that I plugged the thing in, clicked on the network icon in the tray and selected AUTO Mobile Broadband connection - TADAAA, it connected and worked right away, no idea why, I did not even have to enter the #777 for dialing Sprint! Not that I am complaining, but that is the least amount of configuration I ever had to do to get this working on any distro...kudos, big time!
I noticed this too, after going through all the configuration trouble, that CrunchBang incorporates that awesome "auto mobile broadband connection" feature. When I clicked on that, I erroneously thought I was clicking on the connection I had set up.
This is definitely a great feature of #!, since the instructions for setting the thing up manually in KPPP are a PITA!