@awatson20 wrote:
We are integrating Twilio as SMS gateway service for ISE guest notifications. Twilio recommends using E.164 number formatting which requires +1 for US. We would prefer that our guests only enter the 10 digit US number. Is there a way to prepend the US country code (1) in the ISE configuration or through a script so that the guest only has to enter a 10 digit number?
Try this?

This will work for both ISE built-in and portal users.
ISE
=======
<script>
setTimeout(function() {
$("input[name='guestUser.fieldValues.ui_phone_number']").val("+1");
}, 100);
</script>
ISE Portal Builder
===================
<script>
setTimeout(function() {
$("input[data-real-input='guestUser.fieldValues.ui_phone_number']").val("+1");
}, 100);
</script>