Looking for C# code to imbed into webform website to send SMS/MMS

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C#

I'll appreciate help to send SMS/MMS messages using C#.
I used Twilio and got the following error:

"Connection Error: POSThttps://api.twilio.com/2010-04-01/Accounts/ACa48a0c41c1517b0e338fe878e82b5909/Messages.json"

What I have tried:

I used clickSend:

var configuration = new Configuration()
   {
       Username = "zzzz",
       Password = "zzzz"
   };
   var smsApi = new SMSApi(configuration);

   var listOfSms = new List<SmsMessage>
   {
       new SmsMessage(
           to: "+1617xxxxxxx",
           body: "test message 33",
           source: "sdk"
       )
   };
   var smsCollection = new SmsMessageCollection(listOfSms);
   var response = smsApi.SmsSendPost(smsCollection);

No errors, no SMS.

and Twilio:

TwilioClient.Init("zzzz", "xxxx");

            var message1 = MessageResource.Create(
                body: "Join Earth's mightiest heroes.",
                from: new Twilio.Types.PhoneNumber("+1866zzz"),
                to: new Twilio.Types.PhoneNumber("+617zzz")
            );
            Console.WriteLine(message1.Sid);

Error on creating var message:

Connection Error: POSThttps://api.twilio.com/2010-04-01/Accounts/ACa48a0czzzzzzz909/Messages.json