<script>
// check if browser supports SMS
if (navigator.mozSms || navigator.msSms || navigator.sms) {
// browser supports SMS
var smsEnabled = true;
// display the button
document.write('<button>Send SMS</button>');
} else {
// browser does not support SMS
var smsEnabled = false;
document.write('<button>SMS not available</button>');
}
</script>