[arduino code examples for B2]-13 voice call to mobile phone by SIM7600

Code:
/*

 * Made by KinCony IoT: https://www.kincony.com

 *

 * Make a voice call using SIM7600 AT commands.

 * SIM7600 RXD -> ESP32 GPIO16 (TX)

 * SIM7600 TXD -> ESP32 GPIO15 (RX)

 */



#include <Arduino.h>



HardwareSerial modem(2);



constexpr int MODEM_RX = 15;

constexpr int MODEM_TX = 16;

constexpr uint32_t MODEM_BAUD = 115200;



// Time from starting the call until automatic hang-up.

constexpr uint32_t CALL_DURATION_MS = 30000;



const char PHONE_NUMBER[] = "+8615381188302";



bool waitFor(const char *expected, uint32_t timeoutMs) {

  String response;

  uint32_t start = millis();



  while (millis() - start < timeoutMs) {

    while (modem.available()) {

      char c = modem.read();

      Serial.write(c);

      response += c;



      if (response.indexOf(expected) >= 0) {

        return true;

      }



      if (response.indexOf("ERROR") >= 0 ||

          response.indexOf("NO CARRIER") >= 0 ||

          response.indexOf("BUSY") >= 0 ||

          response.indexOf("NO ANSWER") >= 0) {

        return false;

      }

    }

    delay(1);

  }



  Serial.println("\n[Timeout]");

  return false;

}



bool sendAT(const String &command,

            const char *expected = "OK",

            uint32_t timeoutMs = 3000) {

  while (modem.available()) {

    Serial.write(modem.read());

  }



  Serial.print("\n>> ");

  Serial.println(command);



  modem.print(command);

  modem.print('\r');



  return waitFor(expected, timeoutMs);

}



void setup() {

  Serial.begin(115200);

  modem.begin(MODEM_BAUD, SERIAL_8N1, MODEM_RX, MODEM_TX);



  Serial.println("\nWaiting for SIM7600...");

  delay(15000);



  bool modemReady = false;



  for (int i = 0; i < 10; i++) {

    if (sendAT("AT")) {

      modemReady = true;

      break;

    }

    delay(1000);

  }



  if (!modemReady) {

    Serial.println("No modem response. Check power, baud rate and UART pins.");

    return;

  }



  if (!sendAT("ATE0")) return;



  if (!sendAT("AT+CPIN?", "+CPIN: READY")) {

    Serial.println("SIM card is not ready.");

    return;

  }



  // Print signal strength and network registration status.

  sendAT("AT+CSQ");

  sendAT("AT+CREG?");

  sendAT("AT+CEREG?");



  // A trailing semicolon requests a voice call.

  String dialCommand = String("ATD") + PHONE_NUMBER + ";";



  Serial.println("\nDialing...");



  uint32_t callStart = millis();



  if (!sendAT(dialCommand, "OK", 10000)) {

    Serial.println("\nDial command failed or timed out.");

    sendAT("ATH");

    return;

  }



  Serial.println("\nDial command accepted; waiting for call events.");



  String line;

  bool callEnded = false;



  while (millis() - callStart < CALL_DURATION_MS && !callEnded) {

    while (modem.available()) {

      char c = modem.read();

      Serial.write(c);



      if (c == '\n') {

        line.trim();



        if (line == "NO CARRIER" ||

            line == "BUSY" ||

            line == "NO ANSWER" ||

            line == "ERROR") {

          callEnded = true;

        }



        line = "";

      } else if (c != '\r') {

        line += c;

      }

    }

    delay(1);

  }



  if (callEnded) {

    Serial.println("\nCall ended.");

  } else {

    Serial.println("\nHanging up...");

    sendAT("ATH");

  }

}



void loop() {

  // UART bridge for manual AT-command debugging.

  while (modem.available()) {

    Serial.write(modem.read());

  }



  while (Serial.available()) {

    modem.write(Serial.read());

  }

}