alternate serial

int WakeUpPin = 34;

void setup() {
  // put your setup code here, to run once:
  pinMode(WakeUpPin, OUTPUT);

  // initialize both serial ports:
  Serial.begin(9600);
  Serial1.begin(9600);

  Off();
  On();
}

void loop() {

  Serial.println("AT Commands Test");
  Serial.flush(); // pause until transmit buffer is empty
  Serial1.println("AT");
  while(true) {
    // see if a character is available
    if (Serial1.peek() != -1)
      Serial.print(Serial1.read()); // print it out.
  }
}

void On()
{
  digitalWrite(WakeUpPin, LOW);
  delay(10);
  digitalWrite(WakeUpPin, HIGH);
  delay(10);
}
void Off()
{
  digitalWrite(WakeUpPin, LOW);
  delay(10);
}