############################################
#	VARIABLES
############################################
....
# array scotching sms which was readed
my @msg2 = (); 
..........
############################################
# START EXECUTION
############################################
answer_sms();

###########################################
# 	answer_sms()
###########################################

sub answer_sms
{
	#Build gsm object
	$gsm = new Device::Gsm(port=>'/dev/cuaU0');
	# read SMS of Sim card 
	@msg = $gsm->messages('SM');
	# get the number of sms in the card
	$taille = @msg;
	# read the old sms in my sim card
	proc_read_card();
	# creat array for stoching nmbr of sms in the card
	@tab=($taille);
	print "\nWAITING FOR NEW SMS.......\n";
	while(1)
	{
		my $newtime = (time+50);	
		@msg2 =$gsm->messages('SM');
		$taille2 = @msg2;
		push(@tab,$taille2);	
		if($tab[-1] != $tab[-2])
		{
		# get the number of the last sender
                # following the LINE   94#      
                my $dernier_num = $msg2[$#msg2]->sender();
                ................
              $gsm->send_sms(recipient=>$dernier_num,content=>"Error" );
               .............
}
}