Twilio's TwilioRestClient SendSmsMessage returns null

Question

I have everything working locally, but when I test Twilio's service on an Amazon EC2 Debian 6.0.6 server running Mono 2.10.9, I find that sending SMS messages no longer works. I believe the problem lies somewhere in the server configuration, as I am using the latest Twilio (3.5.6), RestSharp (104.1) and JSON.NET (4.5.11) libraries, and I can guarantee that the variables used in the following method call are not empty at runtime.

var client = new Twilio.TwilioRestClient("{my account number}", "{my account token}");
var smsMessage = client.SendSmsMessage("{my account phone number}", "{my mobile phone number}", "Hello World!");

Using ntop, I have seen that there are bytes being sent/received to/form this reqeuest, but the smsMessage result is still null. The SendSMSMessage function utilizes the RestSharp library, particularly the RestClient's Execute function, which invokes a Deserialize method and returns an IRestResponse in which the Data field is null in this case.

I have seen some indications online that the problem may lie in the deserialization process, but, as I've ensured I am using the latest version of JSON.NET, I am not sure what other steps to take here.

Do you have any suggestions on resolving the problem and do you suspect it is a code or server issue? Also do you have any advice, using Debian, how I might further debug this interaction, perhaps even to get the full byte response externally from the application?

Answer 1

In debugging the RestSharp library, I discovered that the exception had to do with SSL and Mono's trusted certificates. The exception message I received is as follows:

Error getting response stream (Write: The authentication or decryption has failed.): SendFailure

Following the instructions in the link below helped me to resolve the issue, particularly by executing the following and restarting mono.

certmgr -ssl https://api.twilio.com

http://www.mono-project.com/FAQ:_Security