GPS SMS

I want to create a GPS tracking Device with arduino Uno.
The Codes Are working but I Dont know how to send it via sms. im using dfrobot tel0097.

I want to send “track” from my phone to the arduino

then it will reply back “the latitude and longitude”.

this is the codes of getting GPS only

/*

Get GPS data

  1. This example is used to test SIM808 GPS/GPRS/GSM Shield’s reading GPS data.
  2. Open the SIM808_GetGPS example or copy these code to your project
  3. Download and dial the function switch to Arduino
  4. open serial helper
  5. Place it outside, waiting for a few minutes and then it will send GPS data to serial

create on 2016/09/23, version: 1.0
by jason

*/
#include <DFRobot_sim808.h>
#include <SoftwareSerial.h>

//#define PIN_TX 10
//#define PIN_RX 11
//SoftwareSerial mySerial(PIN_TX,PIN_RX);
//DFRobot_SIM808 sim808(&mySerial);//Connect RX,TX,PWR,

DFRobot_SIM808 sim808(&Serial);

void setup() {
//mySerial.begin(9600);
Serial.begin(9600);

//******** Initialize sim808 module *************
while(!sim808.init()) {
delay(1000);
Serial.print(“Sim808 init error\r\n”);
}

//************* Turn on the GPS power************
if( sim808.attachGPS())
Serial.println(“Open the GPS power success”);
else
Serial.println(“Open the GPS power failure”);

}

void loop() {
//************** Get GPS data *******************
if (sim808.getGPS()) {
Serial.print(sim808.GPSdata.year);
Serial.print("/");
Serial.print(sim808.GPSdata.month);
Serial.print("/");
Serial.print(sim808.GPSdata.day);
Serial.print(" “);
Serial.print(sim808.GPSdata.hour);
Serial.print(”:");
Serial.print(sim808.GPSdata.minute);
Serial.print(":");
Serial.print(sim808.GPSdata.second);
Serial.print(":");
Serial.println(sim808.GPSdata.centisecond);
Serial.print(“latitude :”);
Serial.println(sim808.GPSdata.lat);
Serial.print(“longitude :”);
Serial.println(sim808.GPSdata.lon);
Serial.print(“speed_kph :”);
Serial.println(sim808.GPSdata.speed_kph);
Serial.print(“heading :”);
Serial.println(sim808.GPSdata.heading);
Serial.println();

//************* Turn off the GPS power ************
sim808.detachGPS();
}

}

Why do you attach the GPS once in setup() and detach it in loop() when the getGPS() function returns true?

I want to send "track" from my phone to the arduino

You want to send an SMS to the Arduino, containing the string "track"? What good will that do, when that code does not read SMSs? If you add code to read SMSs, and you read one containing "track", what do you intend to have happen?