Arduino.ru

#include<SoftwareSerial.h>

SoftwareSerial mySerial(12, 11);

void setup() {
  // Make sure that corresponds to the baud rate of your module
  Serial.begin(115200);
  mySerial.begin(9600);
  // Give time to your GSM shield log on to network
  delay(10000);   
  
  // Send the SMS
  //sendSMS();
  MakeCall();
}

void loop() { 
  
}

void sendSMS() {
  // AT command to set SIM900 to SMS mode
  Serial.print("AT+CMGF=1\r"); 
  delay(100);

  // REPLACE THE X's WITH THE RECIPIENT'S MOBILE NUMBER
  // USE INTERNATIONAL FORMAT CODE FOR MOBILE NUMBERS
  Serial.println("AT+CMGS=\"+xxxxxxxxxxxxxx\"\r"); 
  delay(100);
  
  // REPLACE WITH YOUR OWN SMS MESSAGE CONTENT
  Serial.println("Message example from Wemos D1 R1."); 
  delay(100);

  // End AT command with a ^Z, ASCII code 26
  Serial.println((char)26); 
  delay(100);
  Serial.println();
  // Give module time to send SMS
  delay(5000); 
}

void MakeCall()
{
  mySerial.println("ATD +xxxxxxxxxxxxxx;\r"); // ATDxxxxxxxxxx; -- watch out here for semicolon at the end!!
  Serial.println("Calling  "); // print response over serial port
  delay(1000);
}

Кроме стандартных D1->Tx и D0->Rx ни какие другие пины не могу установить в качестве Serial