Is it possible for Arduino to send a message to the internet without using a GSM shield?
Use this example to open a webpage using a push button, you need Python installed on your Windows.

Step 01:

Upload this sketch to your arduino:

const int buttonPin = 2; // the number of the pushbutton pin
int buttonState = 0;

void setup() {
  Serial.begin(9600);  
  pinMode(buttonPin, INPUT);
}

void loop() {
  buttonState = digitalRead(buttonPin);
  if (buttonState == HIGH) {
  Serial.println("OpenWebPage");
  }
}


The Circuit:


pushbutton attached to pin 2 from +5V
10K resistor attached to pin 2 from ground




Step 02:

Open a text editor and paste this code to a new file:

import serial
from subprocess import call

ser = serial.Serial(
    port='COM5', # Change this to your COM port number
    baudrate=9600,
    parity=serial.PARITY_ODD,
    stopbits=serial.STOPBITS_TWO,
    bytesize=serial.SEVENBITS
)

if (ser.isOpen()):
    print "Serial Port is Open..."
    print "Waiting for a command ..."
    while 1:
        cmd = ser.readline()
        if cmd.strip() == "OpenWebPage":
            print "Received command from Arduino..." 
            print "Opening webpage..." 
            call(["explorer", "http://www.google.com"]) #change it the address you want


Save the file to your desktop, name it : SerialListener.py

Step 03


Now open a Command Prompt window.
Navigate to your desktop folder and execute this command: python SerialListener.py.
You should see Serial Port is Open... Waiting for a command ...
Press the push button, and a webpage should open in your default browser.