/*Validate Phone No*/
$('.valPhoneNo').blur(function(){
 var phone = $(this).val();
 phone = phone.replace(/D/g,'');
 if(phone.length == 7){
  var dispPhone = phone.slice(0,3) + "-" + phone.slice(3);
  $(this).val(dispPhone);
 } else if(phone.length == 10) {
  var dispPhone = "(" + phone.slice(0,3) + ") " + phone.slice(3,6) + "-" + phone.slice(6);
$(this).val(dispPhone);
 }
});

This post is useful on that subject.