Hello, I am doing a code on receiving sms to ask for location using gsm 800l. When i tried separately, i manage to send message automatically when received an sms called "check". However, when i combined the code, i am able to send the location manually through the serial monitor but not by sending sms to ask for location. I will be so grateful if anyone could help me with the code. Thank you 
this is my test code for receiving sms to send message
#include <SoftwareSerial.h>
SoftwareSerial sim(3, 2);
int _timeout;
String _buffer;
String number = "+60127487271"; //-> change with your number
String c;
void setup() {
//delay(7000); //delay for 7 seconds to make sure the modules get the signal
Serial.begin(9600);
_buffer.reserve(50);
Serial.println("Sistem Started...");
sim.begin(9600);
delay(1000);
Serial.println("Type s to send an SMS, r to receive an SMS, and c to make a call");
}
void SendMessage()
{
Serial.println ("Sending Message");
sim.println("AT+CMGF=1"); //Sets the GSM Module in Text Mode
delay(1000);
Serial.println ("Set SMS Number");
sim.println("AT+CMGS=\"" + number + "\"\r"); //Mobile phone number to send message
delay(1000);
String SMS = "Hello, how are you?";
sim.println(SMS);
delay(100);
sim.println((char)26);// ASCII code of CTRL+Z
delay(1000);
_buffer = _readSerial();
}
void RecieveMessage()
{
Serial.println ("SIM800L Read an SMS");
delay (1000);
sim.println("AT+CNMI=2,2,0,0,0"); // AT Command to receive a live SMS
delay(1000);
Serial.write ("Unread Message done");
}
String _readSerial() {
_timeout = 0;
while (!sim.available() && _timeout < 12000 )
{
delay(13);
_timeout++;
}
if (sim.available()) {
return sim.readString();
}
}
void callNumber() {
sim.print (F("ATD"));
sim.print (number);
sim.print (F(";\r\n"));
_buffer = _readSerial();
Serial.println(_buffer);
}
void loop() {
if (Serial.available() > 0)
switch (Serial.read())
{
case 's':
SendMessage();
break;
case 'r':
RecieveMessage();
break;
case 'c':
callNumber();
break;
}
if (sim.available() > 0)
Serial.write(sim.read());
if (sim.available() > 0)
{
String c= sim.readString();
c.trim();
if (c.indexOf("check")>=0)
{ SendMessage();
sim.print("\r");
delay(1000);}
}}
this is my code when combined with gps
#include <TinyGPS++.h>
#include <SoftwareSerial.h>
//gsmmodule
SoftwareSerial sim(3, 2);
int _timeout;
String _buffer;
String number = "+60127487271"; //-> change with your number
//gpsmodule
static const int RXPin = 11, TXPin = 12;
static const uint32_t GPSBaud = 9600;
// The TinyGPS++ object
TinyGPSPlus gps;
// The serial connection to the GPS device
SoftwareSerial ss(RXPin, TXPin);
void setup() {
//delay(7000); //delay for 7 seconds to make sure the modules get the signal
Serial.begin(9600);
_buffer.reserve(50);
Serial.println("Sistem Started...");
sim.begin(9600);
delay(1000);
Serial.println("Type s to send an SMS, r to receive an SMS, and c to make a call");
ss.begin(GPSBaud);
}
void SendMessage()
{
Serial.println ("Sending Message");
sim.println("AT+CMGF=1"); //Sets the GSM Module in Text Mode
delay(1000);
Serial.println ("Set SMS Number");
sim.println("AT+CMGS=\"" + number + "\"\r"); //Mobile phone number to send message
delay(1000);
float SMS1 = (gps.location.lat());
float SMS2 = (gps.location.lng());
sim.print("https://www.google.com/maps/?q=");
sim.print(SMS1,6);
sim.print(",");
sim.print(SMS2,6);
delay(100);
sim.println((char)26);// ASCII code of CTRL+Z
delay(1000);
_buffer = _readSerial();
}
void RecieveMessage()
{
Serial.println ("SIM800L Read an SMS");
delay (1000);
sim.println("AT+CNMI=2,2,0,0,0"); // AT Command to receive a live SMS
delay(1000);
Serial.write ("Unread Message done");
}
String _readSerial() {
_timeout = 0;
while (!sim.available() && _timeout < 12000 )
{
delay(13);
_timeout++;
}
if (sim.available() > 0)
Serial.write(sim.read());
if (sim.available() > 0)
{
String c= sim.readString();
c.trim();
if (c.indexOf("OKAY")>=0)
{
sim.print("\r");
delay(1000);}
}
}
void callNumber() {
Serial.println ("Calling...");
sim.print (F("ATD"));
sim.print (number);
sim.print (F(";\r\n"));
_buffer = _readSerial();
Serial.println(_buffer);
}
void loop(){
if (Serial.available() > 0)
switch (Serial.read())
{
case 's':
SendMessage();
break;
case 'r':
RecieveMessage();
break;
case 'c':
callNumber();
break;
}
if (sim.available() > 0)
Serial.write(sim.read());
// This sketch displays information every time a new sentence is correctly encoded.
if (sim.available() > 0)
{
String c= sim.readString();
c.trim();
if (c.indexOf("check")>=0)
{ SendMessage();
sim.print("\r");
delay(1000);}
}
while (ss.available() > 0){
gps.encode(ss.read());
if (gps.location.isUpdated()){
Serial.print("Latitude= ");
Serial.print(gps.location.lat(), 6);
Serial.print(" Longitude= ");
Serial.println(gps.location.lng(), 6);
}
}
}