register_globals shouldnt matter here, zhabala, since scoppc has already taken care of that by using $_GET['MSISDN']
What if you test by using
echo $_GET['MSISDN'];
in smsbox.php?
If it works, then it could imply that the include isnt working (wrong path?), but is simply being silently discarded as error reporting is not set to include E_NOTICE
Perhaps using require() would be better?