code: function TwilioErrorStatus(response) {
    MessagingServiceStatus.call(this, 'twilio');
    
    // There was an error when attempting to send message
    this.state.message = response.message + ': ' + response.moreInfo;
  
    // See https://www.twilio.com/docs/errors/reference for status error codes
    if (response.code == 20003 || response.code == 20005) this.state.code = this.StatusCodes.LIMIT_EXCEEDED; // should only be code 20005, but Twilio doesn't seem to follow its own documentation
    else if (response.code == 21606) this.state.code = this.StatusCodes.DATA_REJECTED;
    else if (response.code == 21211) this.state.code = this.StatusCodes.DATA_REJECTED;
    else this.state.code = this.StatusCodes.DEFAULT;
  }
docs: /*
  Error Status
  
  @param response     JSON response object from Twilio service