arduino receive sms

Hello, I start in arduino and I made a code that can send sms / phone calls. My code is not perfect and I'm asking you for some help to improve it:

I do not know how to get a SMS / phone call by cons. I would like to display the SMS I get in the void function Get_SMS (), but I found 2-3 things on the net but I did not understand how to do it. if anyone could teach me.

#include <SoftwareSerial.h>


SoftwareSerial SIM900(7, 8);

char message=0;

void setup()
{
SIM900.begin(19200);
delay(25000);
Serial.begin(19200);
Serial.println("OK");

digitalWrite(9, HIGH);
delay(1000);
}

void Send_Call()
{
    SIM900.println("ATD 0608446677;");
    delay(100);
    SIM900.println();
    //delay(120000);
    while(Serial.read() != '1') {
        delay(100);
    }
    SIM900.println("ATH");
    delay(1000);
}

void Send_SMS()
{
    SIM900.print("AT+CMGF=1\r");
    delay(100);
    SIM900.println("AT+CMGS=\"0608446677\"");
    delay(100);
    SIM900.println("test sms");
    delay(100);
    SIM900.println((char)26);
    delay(100);
    SIM900.println();
    delay(5000);
    Serial.println("SMS sent successfully");
}

void Get_SMS()
{
    message=SIM900.read();
    Serial.print(message);
}

void Get_Call()
{

}


void loop() {

    if(Serial.read() == 'p') {
        Send_Call();
    }

    if(Serial.read() == 's') {
        Send_SMS();
    }

    Get_SMS();
    Get_Call();

}

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