I have exchanged few messages with John Wang around 4 months ago under this questions https://devcommunity.ringcentral.com/ringcentraldev/topics/how-to-attaching-pdf-to-a-fax-messaege and was asking if we can go to production with csharp SDK. He told me "SDK is under active development and the interfaces are changing. We anticipate moving this out of alpha in a few weeks after which time the interface will be much more stable for backward compatibility purposes."

On Github I still see version 0.1.0 for ringcentral-csharp. Is this stable enough that we can use it on our production environment for fax and sms? or should I wait for version 1.0?