Send SMS on Arduino Mega 2560 with Sim808 Development Board

I am trying to send an SMS message on my Arduino Mega with this GSM board: https://www.amazon.co.uk/Development-Antenna-Support-Raspberry-Wishiot/dp/B07Q1B9FKZ

I can make and receive calls, and receive texts, but I can't seem to send a text. Here is my code (stole from SIM900 GSM GPRS Shield with Arduino | Random Nerd Tutorials

void setup() {
Serial.begin(19200);
Serial1.begin(19200);
delay(20000);

sendSMS();
}

void loop() {

}

void sendSMS() {
Serial1.print("AT+CMGF=1\r");
delay(100);

Serial1.println("AT + CMGS = "+XXXXXXXXXXXX""); //My number in International Format
delay(100);

Serial1.println("Message example from Arduino.");
delay(100);

Serial1.println((char)26);
delay(100);
Serial1.println();
// Give module time to send SMS
delay(5000);
Serial.println("DONE");
}

Check the board rate and you may need to send the module
Serial1.print("AT");
and a short delay in setup() before sendSMS().