Welcome to the RingCentral Community

The RingCentral API is a REST API that returns JSON format data for most responses. We also have a new alpha C# SDK that is under active development. Some relevant links and information for your quests are below:

(1) The REST API reference is available online here:

Docs: https://developers.ringcentral.com/api-docs/latest/index.html

(2) We are in the process of rolling out a C# SDK. This SDK is currently an alpha release so we are expecting the API may change before it is finalized. 

Nuget: http://www.nuget.org/packages/RingCentralSDK/
GitHub: https://github.com/ringcentral/ringcentral-csharp (develop branch)

(3) Regarding MSSQL 2012 format, since we return JSON and MSSQL is a relational database, you'll have to do the necessary conversion to save the data in MSSQL. Of note, our datetime format is in ISO 8601 which is supported by MSSQL.