The Esendex .Net SDK is an easy to use client for our REST API that you can use to integrate SMS and Voice messaging into your .Net application. http://developers.esendex.com
I've done some work around a dotnet core version as a subproject in https://github.com/dktc/esendex-dotnet-sdk I've been using it to send SMS messages and it builds OK, but I didn't want to publish as a pull request as I've only tested a small section of it, the bits I need.
Anyway, thought I'd let you know in case you want to use it as a starting block for future dev work.