The Mobile Broadband API is used to implement connectivity to cellular networks. Applications should not communicate with such mobile broadband devices directly. Instead, they must use the Mobile Broadband API.
The Mobile Broadband API is designed for C++ developers.
There is also an interface for .NET developers using C#. For details, read this whitepaper.
The Mobile Broadband API can be used by third-party applications that need to control and manage mobile broadband interfaces.
Mobile Broadband support begins with Windows 7.