'123456','user2' => '234567','user3' => '345678',);
	$getmobile = array('user1' => '9930447726','user2' => '9769818858','user3' => '9619141191',);
	
	/////////////////////////////////////////////////////////////////////////////
	//            Your Login Credentials with SMSGatewayCenter.com             //
	/////////////////////////////////////////////////////////////////////////////
	$smsgatewaycenter_com_user = "YourUsername"; //Your SMS Gateway Center Account Username
	$smsgatewaycenter_com_password = "********";  //Your SMS Gateway Center Account Password
	$smsgatewaycenter_com_url = "https://www.yoursmsproviderdomain.com/library/send_sms_2.php?"; //SMS Gateway Center API URL
	$smsgatewaycenter_com_mask = "SGCSMS"; //Your Approved Sender Name / Mask
	
	/////////////////////////////////////////////////////////////////////////////
	// Function to Initiate SMS Message with SMS Gatewaycenter.com using CURL  //
	/////////////////////////////////////////////////////////////////////////////
	function smsgatewaycenter_com_Send($mobile, $sendmessage, $debug=false){
		global $smsgatewaycenter_com_user,$smsgatewaycenter_com_password,$smsgatewaycenter_com_url,$smsgatewaycenter_com_mask;
		$parameters = 'UserName='.$smsgatewaycenter_com_user;
		$parameters.= '&Password='.$smsgatewaycenter_com_password;
		$parameters.= '&Type=Individual';
		$parameters.= '&Language=English';
		$parameters.= '&Mask='.$smsgatewaycenter_com_mask;
		$parameters.= '&To='.urlencode($mobile);
		$parameters.= '&Message='.urlencode($sendmessage);
		$apiurl =  $smsgatewaycenter_com_url.$parameters;
		$ch = curl_init($apiurl);
		curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
		$curl_scraped_page = curl_exec($ch);
		curl_close($ch);
		
		if ($debug) {
			echo "Response: 
" . $curl_scraped_page . "
";
		}
		return($curl_scraped_page);
	}
	/////////////////////////////////////////////////////////////////////////////
	//      Function to generate and append OTP code within the message        //
	/////////////////////////////////////////////////////////////////////////////
	function smsgatewaycenter_com_OTP($length = 8, $chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPRQSTUVWXYZ0123456789'){
		$chars_length = (strlen($chars) - 1);
		$string = $chars{rand(0, $chars_length)};
		for ($i = 1; $i < $length; $i = strlen($string)){
			$r = $chars{rand(0, $chars_length)};
			if ($r != $string{$i - 1}) $string .=  $r;
		}
		return $string;
	}
	/////////////////////////////////////////////////////////////////////////////
	//           If Debug is set to true below, then response from             //
	//         SMSGatewayCenter.com API will be printed on the screen          //
	/////////////////////////////////////////////////////////////////////////////
	$debug = false; //Set to true if you want to see the response
	
	/////////////////////////////////////////////////////////////////////////////
	//     If user has not posted anything, lets load the user login page      //
	/////////////////////////////////////////////////////////////////////////////
	
	if (empty($_POST)){
		$i = 0;
		echo '   
		
			
				One Time Password Form
				
			
		';
	}
	/////////////////////////////////////////////////////////////////////////////
	//   If form has been submitted by the user, lets create OTP or validate   //
	/////////////////////////////////////////////////////////////////////////////
	
	if (isset($_POST['sendsms'])){
		$_SESSION['smsgatewaycenterotp'] = smsgatewaycenter_com_OTP(); //Generate OTP
		/////////////////////////////////////////////////////////////////////////////
		//             Lets validate user credentials with getuserarray            //
		/////////////////////////////////////////////////////////////////////////////
		$username = $_POST['username'];
		$password = $_POST['password'];
		
		if ($password != $getuser[$_POST['username']] || ((empty($_POST['username']) && (!empty($_POST['password'])))) || (empty($_POST['password']) && (!empty($_POST['username'])))){
			echo 'Please enter a valid username or password!'; //username and password does not match
		}
		elseif ((!empty($_POST['submit'])) && (empty($_POST['password'])) && (empty($_POST['username']))){
			echo 'No username or password entered'; //Empty form submitted
		}
		elseif ($password == $getuser[$_POST['username']]){
			/////////////////////////////////////////////////////////////////////////////            
			// User has successfully validated credentials, lets append OTP and send   //
			// and send the SMS to recipient's mobile number to authenticate OTP       //
			/////////////////////////////////////////////////////////////////////////////       
			smsgatewaycenter_com_Send($getmobile[$_POST['username']],'Dear '.$username.'! Please authenticate your OTP. Your One Time password is: '.$_SESSION['smsgatewaycenterotp'],$debug);
			echo '
			
				
					Authenticate OTP (One Time Password)
					We have sent an SMS to your registered phone number, please authenticate your one time password entering below.
					
				
			';
		}
	}
	elseif (isset($_POST['submitotp'])){
		///////////////////////////////////////////////////////////////////////////// 
		//      Lets validate user's OTP and validate with the stored session      //
		/////////////////////////////////////////////////////////////////////////////
		$sgc_otp = $_POST['getsmsgatewaycenterotp'];
		if($_SESSION['smsgatewaycenterotp'] == $sgc_otp){
			echo '
			
				
					You\'ve been successfully verified your One-Time Password
				
			';
		} else { 
			echo'
			
				
					Wrong Password!
				
			';
		}
	}