After purchasing a Sprint broadband card I wanted to see if there was a way to make it work with Ubuntu Linux. After lots of searching I found a document on Sprints web site that details the steps required to get their broadband cards working. The card I purchased was the Pantech PX-500. I am using Ubuntu 7.04, so the instructions were a little different. I had no need to configure the modem for graphical access, I just wanted a simple script I could run to share broadband using my old Linux laptop.
Here are the steps I followed to get the card working:

1. Follow the steps on pages 21-22 of the Sprint guide.
2. Setup masquerading on your Linux box. I used the command "sudo iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -o ppp0 -j MASQUERADE". This will be different depending on your network configuration.
   
3. And the final step that was somewhat hard to figure out was to setup IP forwarding. This was the magic trick to completing the whole setup "sudo sysctl -w net.ipv4.ip_forward=1". There appears to be several ways to make this work, but using sysctl was the only way I could make it work with my specific configuration.
4. Bring up your connection with "sudo wvdial" and enjoy!