How to send an SMS in a language other than English with module SIM800L?

Question

How to send a text message in Polish, e.g. with the following text "Cześć", where the characters are from outside the GSM alphabet? I have a TTGO T-Call board that has a SIM800L module from SIMCOM. I have tried using various AT commands, but nothing works. Has anyone encountered a similar problem? Thank you very much for your help!

Answer 1

According to the GSM specification 3GP TS 127.007, the magic command to declare that you want to send UCS2 characters (16 bits unicode) is:

AT+CSCS="UCS2"

From that point you must send the hex values of the unicode characters. The example says that to send Abc you actually send 004100620063. So to send Cześć it would be 0043007a0065015b0107

Answer 2

This is the working code for TTGO T-CALL 1.3/1.4 SIM800L

#define SIM800L_RX     27
#define SIM800L_TX     26
#define SIM800L_PWRKEY 4
#define SIM800L_RST    5
#define SIM800L_POWER  23

void Send_AT(String command) {
  Serial.println("AT: " + command);
  Serial2.println(command);
  long timer = millis();
  while (timer + 3000 > millis()) {
    while (Serial2.available()) {
      Serial.write(Serial2.read());
    }
  }
  Serial.println();
}

void setup() {
  pinMode(SIM800L_POWER, OUTPUT);
  digitalWrite(SIM800L_POWER, HIGH);
  Serial.begin(115200);
  Serial2.begin(9600, SERIAL_8N1, SIM800L_TX, SIM800L_RX);
  delay(1000);
  Serial.println("--- Loading Firmware ---\n");
  delay(5000);
  Serial.println("--- (C) 2022 by Dawid Irzyk ---");
  Serial.println("");
  while (Serial2.available()) {
    Serial.write(Serial2.read());
  }
}

void SendMessage()
{
  Serial2.print("ATZ\r\n");
  delay(2000);
  Serial2.print("AT+CSCS=\"HEX\"\r\n");
  delay(2000);
  Serial2.print("AT+CSMP=17,168,0,8\r\n");
  delay(2000);
  Serial2.print("AT+CMGF=1\r\n");
  delay(2000);
  Serial2.print("AT+CMGS=\"+48123123123\"\r\n");
  delay(2000);
  Serial2.print("0043007a0065015b0107");
  delay(2000);
  Serial2.println((char)26);
}

void loop() {

  SendMessage();

  while (true) {
    delay(1000);
  }
}