Response: StatusCode: 404, ReasonPhrase: 'Not Found', Version: 1.1, Content: System.Net.Http.StreamContent, Headers: { Connection: keep-alive RCRequestId: 56564a9c-9ec3-11ea-9c69-005056af5c03 RoutingKey: IAD01P13PAS06 X-Rate-Limit-Group: medi

Here is the code you asked for in this issue.

public async Task<object> Read(FaxReadType faxReadType)
{
        object returnData = null;
        try
        {
            using (RestClient rc = new RestClient(RINGCENTRAL_CLIENTID
                                                , RINGCENTRAL_CLIENTSECRET
                                                , IS_PRODUCTION))
            {
                TokenInfo tokenInfo = await rc.Authorize(RINGCENTRAL_USERNAME
                                                        , RINGCENTRAL_EXTENSION
                                                        , RINGCENTRAL_PASSWORD);

                if (rc.token.access_token.Length > 0)
                {
                    switch (faxReadType)
                    {
                        case FaxReadType.ReadContent:
                            ReadMessageContentParameters read = new ReadMessageContentParameters
                            {
                                contentDisposition = "Attachment"
                            };

                            returnData = await rc.Restapi().Account().Extension()
                                            .MessageStore(messageId).Content(attachmentId).Get(read);
                            break;

                        case FaxReadType.ReadMessage:
                            returnData = await rc.Restapi().Account().Extension()
                                            .MessageStore(messageId).Get();
                            break;
                    }
                }
            }
        }
        catch (Exception ex)
        {
            //Log exception in DB
        }
        return returnData;
    }