Hi guys as the title says i am currently working on the project to make the smart intercom , The main components i am using for this project are Arduino Mega 2560, GSM SHIELD, JHD 162A LCD Screen 8pin 4x4 Hex keypad, electric magnet , and some push buttons.
The project should work as follows
1: when i press the button it should call the number .
2: when i send the sms to GSM shield character 1 it should switch off the magnet
3: when i enter password in keypad it should also switch off the magnet
4: when i press the other push button it should also switch off the magnet
The problem i have is that the system works sometime well and some times some functions lag like lcd prints screen too late or some times when i press the button it does not initiate phone call what i am looking for is the improvement of the Code i am using below would really appreciate 
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Below is the program i use:
#include <GSM.h>
#include <LiquidCrystal.h>
#include <Keypad.h>
#include <Password.h>
Password password = Password( "1234" );
// PIN Number
#define PINNUMBER ""
// initialize the library instance
GSM gsmAccess; // include a 'true' parameter for debug enabled
GSMVoiceCall vcs;
GSM_SMS sms;
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(33, 31, 29, 27, 25, 23);
char charbuffer[20];
char senderNumber[20];
int callbutton = 35 ;
int indoorbutton = 37 ;
int magnet = 39 ;
int xyz = 0;
const byte ROWS = 4; //four rows
const byte COLS = 4; // four columns
char keys[ROWS][COLS] = {
{'1','2','3','F'},
{'4','5','6','E'},
{'7','8','9','D'},
{'A','0','B','C'}
};
byte rowPins[ROWS] = {28, 26, 24, 22}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {36, 34, 32,30}; //connect to the column pinouts of the keypad
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
void setup()
{
// initialize serial communications
Serial.begin(38400);
keypad.addEventListener(keypadEvent);
lcd.begin(16, 2);
pinMode(callbutton,INPUT);
pinMode(magnet,OUTPUT);
digitalWrite(magnet,HIGH);
digitalWrite(indoorbutton,HIGH);///// active low
digitalWrite(callbutton,HIGH); //// Active LOW
pinMode(indoorbutton,INPUT);
// connection state
boolean notConnected = true;
// Start GSM shield
// If your SIM has PIN, pass it as a parameter of begin() in quotes
while(notConnected)
{
if(gsmAccess.begin(PINNUMBER)==GSM_READY)
notConnected = false;
else
{
Serial.println("Not connected");
delay(1000);
}
}
vcs.hangCall(); // This makes sure the modem notifies correctly incoming events
Serial.println("GSM initialized.");
}
void loop()
{
//we put all read buttons here !!!!!!
callbutton = digitalRead(35) ;
indoorbutton = digitalRead(37);
keypad.getKey();
if (xyz == 0){
lcd.setCursor(0,0);
lcd.print("Press the button");
lcd.setCursor(0, 1);
lcd.print("to call owner");
}
if (xyz == 1) {
lcd.setCursor(0, 0); /////////// put timer here would look cooler
lcd.print("Call established");
}
if (callbutton == LOW){
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Calling Owner");
vcs.voiceCall("0555566340");
}
xyz = 0;
switch (vcs.getvoiceCallStatus())
{
case IDLE_CALL:
break ;
case CALLING:
break ;
case TALKING:
xyz = 1;
break ;
case RECEIVINGCALL:
vcs.answerCall();
break;
}
////////////////////// SMS program
char c;
// If there are any SMSs available()
if (sms.available())
{
Serial.println("Message received from:");
// Get remote number
sms.remoteNumber(senderNumber, 20);
Serial.println(senderNumber);
// An example of message disposal
// Any messages starting with # should be discarded
if (sms.peek() == '#')
{
Serial.println("Discarded SMS");
sms.flush();
}
// Read message bytes and print them
while (c = sms.read())
{
Serial.println(c);
if(c == '1'){
digitalWrite(magnet,LOW);
delay(6000);
digitalWrite(magnet,HIGH); }
Serial.println("END OF MESSAGE");
// Delete message from modem memory
sms.flush();
Serial.println("MESSAGE DELETED");
}
delay(1000);
}
}
//take care of some special events
void keypadEvent(KeypadEvent eKey){
switch (keypad.getState()){
case m_key::PRESSED :
Serial.print("Pressed: ");
Serial.println(eKey);
switch (eKey){
case 'A': checkPassword(); break;
case 'C': password.reset(); break;
default: password.append(eKey);
}
}
}
void checkPassword(){
if (password.evaluate()){
Serial.println("Success");
digitalWrite(magnet,LOW);
delay(6000);
digitalWrite(magnet,HIGH);
}else{
Serial.println("Wrong");
//add code to run if it did not work
}
if(indoorbutton == LOW)
{
digitalWrite(magnet,LOW);
delay(6000);
digitalWrite(magnet,HIGH);
}
}