static void Main(string[] args) { // Find your Account Sid and Auth Token at twilio.com/user/account string AccountSid = "ACXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"; string AuthToken = "your_auth_token"; var twilio = new TwilioRestClient(AccountSid, AuthToken); var options = new DomainOptions(); options.FriendlyName = "My Domain"; options.VoiceUrl = "https://demo.twilio.com/welcome"; options.AuthType = "IP_ACL"; options.DomainName = "marlo.sip.twilio.com"; var domain = twilio.CreateDomain(options); Console.WriteLine(domain.Sid); }