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 PhoneNumberOptions();
        options.VoiceUrl = "http://demo.twilio.com/docs/voice.xml";
        options.SmsUrl = "http://demo.twilio.com/docs/sms.xml";

        twilio.UpdateIncomingPhoneNumber("PN2a0747eba6abf96b7e3c3ff0b4530f6e", options);
    }
    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";
        string CurrentAccount = "ACXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
        var twilio = new TwilioRestClient(AccountSid, AuthToken, CurrentAccount);

        var options = new PhoneNumberOptions();
        options.AccountSid = "ACXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";

        twilio.UpdateIncomingPhoneNumber("PN2a0747eba6abf96b7e3c3ff0b4530f6e", options);
    }