Use arduino nano for automatic open of an intercom(interphone) when dialing (digital one)

Hi,
Starting from this post Use Arduino nano for automatic open of an intercom(interphone) when dialing I want to do the same for the digital version of the interphone.
I know that can be done because I saw one for selling but I want to extend it to ESP8266 + Home Asisstant.

I connect +14V to Arduino Vin, GND to GND, DATA to Arduino D4 and COM to Arduino D2. I am able to get the trigger by using this code:

int Call = 2;
int Answer = 4;

void setup() {
  Serial.begin(9600);
  pinMode(Call, INPUT);
  pinMode(Answer, OUTPUT);
  digitalWrite(Answer,HIGH);
  Serial.println("start");
}

void loop() {
  int calling = digitalRead(Call);
  if(calling == 1) {
    Serial.println("Calling");
  }
  delay(1);
}

But I'm not able to answer and to open the door.
I tried to set the digitalWrite(Answer,LOW); and digitalWrite(Answer,HIGH); but nothing changed.
If you have any idea it will be great.
Thank you!