I'd like to put together a compile of resources available for Windows Mobile Broadband driver developers and testers. I'll keep updating and please feel free to add to the list via comments:
1- Resources listed in Networking Developer Platform Center: http://msdn.microsoft.com/en-us/network/dd579153.aspx. Scroll down the page.
2- There is no Mobile Broadband driver sample in WDK, however, one of the other NDIS driver samples will be helpful, at least for the common NDIS code part. Usbnwifi 6.20 may be a good fit: http://msdn.microsoft.com/en-us/library/dd163318.aspx. You can find it in WDK source tree at src\network\ndis\usbwifi.
3- General info on NDISTest :
4- Ndis blog. Check out 'How to run NDISTest outside DTM post: http://blogs.msdn.com/ndis/default.aspx
Stay tuned for more and please feel free to add to the list.