Debugging a HTTPGet on SIM900 Library

Hi guys,

Im still trying to debug my SIM900 core board module using the SIM900 library.

Im trying to understand each step of the sketch Im using to see why it fails where it does. The sketch is as follows and I have a specific question at the end of this post in red:

#include "SIM900.h"
#include <SoftwareSerial.h>
#include "inetGSM.h"
//#include "sms.h"
//#include "call.h"

//To change pins for Software Serial, use the two lines in GSM.cpp.

//GSM Shield for Arduino
//www.open-electronics.org
//this code is based on the example of Arduino Labs.

//Simple sketch to start a connection as client.

InetGSM inet;
//CallGSM call;
//SMSGSM sms;

char msg[50];
int numdata;
char inSerial[50];
int i=0;
boolean started=false;

void setup() 
{
  //Serial connection.
  Serial.begin(9600);
  Serial.println("GSM Shield testing.");
  //Start configuration of shield with baudrate.
  //For http uses is raccomanded to use 4800 or slower.
  if (gsm.begin(2400)){
    Serial.println("\nstatus=READY");
    started=true;  
  }
  else Serial.println("\nstatus=IDLE");
  
  if(started){
    //GPRS attach, put in order APN, username and password.
    //If no needed auth let them blank.
    if (inet.attachGPRS("internet.tigo.hn", "", "")) //internet.
      Serial.println("status=ATTACHED");
    else Serial.println("status=ERROR");
    delay(1000);
    
    //Read IP address.
    gsm.SimpleWriteln("AT+CIFSR");
    delay(5000);
    //Read until serial buffer is empty.
    gsm.WhileSimpleRead();
  
    //TCP Client GET, send a GET request to the server and
    //save the reply.
    numdata=inet.httpGET("www.google.com", 80, "/", msg, 50);
    
    // REPLACE THIS GET WITH A POST...
    
    //Print the results.
    Serial.println("\nNumber of data received:");
    Serial.println(numdata);  
    Serial.println("\nData received:"); 
    Serial.println(msg); 
  }
};

void loop() 
{
  //Read for new byte on serial hardware,
  //and write them on NewSoftSerial.
  serialhwread();
  //Read for new byte on NewSoftSerial.
  serialswread();
};

void serialhwread(){
  i=0;
  if (Serial.available() > 0){            
    while (Serial.available() > 0) {
      inSerial[i]=(Serial.read());
      delay(10);
      i++;      
    }
    
    inSerial[i]='\0';
    if(!strcmp(inSerial,"/END")){
      Serial.println("_");
      inSerial[0]=0x1a;
      inSerial[1]='\0';
      gsm.SimpleWriteln(inSerial);
    }
    //Send a saved AT command using serial port.
    if(!strcmp(inSerial,"TEST")){
      Serial.println("SIGNAL QUALITY");
      gsm.SimpleWriteln("AT+CSQ");
    }
    //Read last message saved.
    if(!strcmp(inSerial,"MSG")){
      Serial.println(msg);
    }
    else{
      Serial.println(inSerial);
      gsm.SimpleWriteln(inSerial);
    }    
    inSerial[0]='\0';
  }
}

void serialswread(){
  gsm.SimpleRead();
}

Q/ What do serialhwread() and serialswread() methods do? Why do we need to read data from both hw and sw? I see in the comments that hwread reads bytes on hw serial, which are 18/19 on my MEGA and writes them to a SoftSerial and then we use the method serialswread to read those bytes. Im trying to picture what is happening in reality when this code runs.

I understand the sketch (in setup()) makes an httpGET request. But then in the loop() it calls serialhwread() and serialswread(). I see that a comment at the top says that to change the SoftwareSerial pins to use the GSM.cpp file. That file specifies that TX=2 & RX=3 are those software serials btw.