Phone Number Validate JQuery

This script will check following thing in Phone

1. Phone is not String
2. Phone number must not starting with 0 or 1

jQuery('#phone').keyup(function (e)

{

var phonevalidate = jQuery('#phone').val();

    var checkfirstval = phonevalidate.charAt(0);

if(checkfirstval==0 || checkfirstval==1){

jQuery('#phone').val('');

}

var regEx=/[^0-9]/;

var checkstring = regEx.test(phonevalidate);

if(checkstring){

jQuery('#phone').val('');

}

});

Note: Here input id is phone.