I am new in C# but please allow me to share my understanding…
MC879x supports both AT and CnS. Sierra Wireless offers C++ SDK which based on CnS.
If you want to use C#, there are several options,
- develop your own C# program which communicate with MC879x using AT command or CnS.
- marshal and call the unmanaged C++ class provided in SDK API
(1) is straight forward and you only implement the feature you needed with full control.
However, if you are good at PInvoke and marshaling, (2) is a good choice providing full features already implemented in SDK. I tried to manually call those API in SDK using C# and it’s working fine. As you may know, there are also some tools can help for example SWIG and PInvoker.
Hope this helps.