Set initialCountry to 'auto' and pass in a function for geoIpLookup to perform a JSONP request to ipinfo.io, which returns the user's country based on their IP address.
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<input id="phone" type="tel">
var input = document.querySelector("#phone");
window.intlTelInput(input, {
initialCountry: "auto",
geoIpLookup: function(callback) {
$.get('https://ipinfo.io', function() {}, "jsonp").always(function(resp) {
var countryCode = (resp && resp.country) ? resp.country : "";
callback(countryCode);
});
},
utilsScript: "../../build/js/utils.js?1541153396801" // just for formatting/placeholders etc
});