Html of input box:
<input type="tel" name="password" id="password" value="" placeholder="Enter password"
onfocus="changeToPassword()">
Javascript:
// change the type of the input to password
function changeToPassword() {
setTimeout(function () {
document.getElementById("password").setAttribute("type", "password")
}, 500);
}
this solution works on the iphone. This is kind of a hack. Once you have the number pad in the next 500 miliseconds you change the attribut to password and that tricks the phone.