using RestSharp;

namespace [your-namespace]
{
    public class [your-class]
    {
        public string SendText()
        {
            var client = new RestClient("https://www.callfire.com/api/1.1/rest/");
            client.Authenticator = new HttpBasicAuthenticator("YourLoginId", "password");

            var request = new RestRequest("text", Method.POST);
            request.AddParameter("Type", "TEXT");
            request.AddParameter("To", "13105551212");
            request.AddParameter("Message", "Hello, just testing SMS messaging");

            var response = client.Execute(request);
            string content = response.Content;
            return content;
        }
    }
}