File content as of revision 0:5c1655777e38:

#include "mbed.h"
#include "USBSerial.h"
//#include "string.h"

// Blinking rate in milliseconds
#define BLINKING_RATE_MS                                                    500
#define CTRL_Z              26      //Attach at the end of this message string

// Virtual serial port over USB
USBSerial microUSB;
Serial SIM800L(P0_1, P0_0); //tx, rx
// Serial pc(USBTX, USBRX);
char buf[40];
char buf1[40];
long GSMBAUD = 9600;
// long PCBAUD  = 9600;

int main()
{
    // Initialise the digital pin LED1 as an output
    //DigitalOut led(LED1);

    SIM800L.baud(GSMBAUD);
    //microUSB.scanf("%s", buf);    
    SIM800L.puts("AT\r\n");
    SIM800L.scanf("%s", buf);
    SIM800L.scanf("%s", buf1);
    microUSB.printf("%s" , buf);
    microUSB.printf("%s\n", buf1);
    
    SIM800L.puts("AT+CMGF=1\r\n");
    SIM800L.scanf("%s", buf);
    SIM800L.scanf("%s", buf1);
    microUSB.printf("%s" , buf);
    microUSB.printf("%s\n", buf1);
    
    SIM800L.puts("AT+CMGS=\"17039739276\"\r\n");
    
    wait(0.1f);

    SIM800L.printf("This is the automatted program SMS from SIM800L. :D %c\r\n", CTRL_Z);
    
    SIM800L.scanf("%s", buf);
    SIM800L.scanf("%s", buf1);
    microUSB.printf("%s" , buf);
    microUSB.printf("%s\n", buf1);
    
    wait(1);

    //pc.printf("Yike");
    SIM800L.puts("AT+CMGF=0\r\n");
    SIM800L.scanf("%s", buf);
    SIM800L.scanf("%s", buf1);
    microUSB.printf("%s" , buf);
    microUSB.printf("%s\n", buf1);
        //led = !led;
//        pc.printf("regular serial communication works!");
        //microUSB.printf("you typed: %s\r\n",buf);
        //microUSB.printf("\x1B[2J");  //clear terminal program screen
//        while (SIM800L.readable()){
//               microUSB.printf("%c", microUSB.putc((SIM800L.getc())));
//        
}