var nums=new Array('document.forms[0].dnn$ctr2113$DynamicForms$TextBoxResponses_GUIDe6a98a7c-7f8b-41d5-bfe4-e7138d284faatxtPhone', 'document.forms[0].dnn$ctr2113$DynamicForms$TextBoxResponses_GUID87b851f3-2f38-4019-9ffc-131983d4aee4txtFax');

function doThis(){

var re= /\D/;
// test for this format: (xxx)xxx-xxxx
var re2 = /^\({1}\d{3}\)\d{3}-\d{4}/; 
// test for this format: xxx-xxx-xxxx
//var re2 = /^\d{3}-\d{3}-\d{4}/;

for (i=0; i<nums.length;i++){
var num=eval(nums[i]+'.value');

var newNum;
 if (num != "" && re2.test(num)!=true){
   if (num != ""){
     while (re.test(num)){
     num = num.replace(re,"");
     }
   }

  if (num.length != 10){
    alert('Please enter a 10 digit phone number');
    eval(nums[i]).select();
    break;
    }
   else {
     // for format (xxx) xxx-xxxx
     newNum = '(' + num.substring(0,3) + ') ' + num.substring(3,6) + '-' + num.substring(6,10);
     // for format xxx-xxx-xxxx
     // newNum = num.substring(0,3) + '-' + num.substring(3,6) + '-' + num.substring(6,10);
     eval(nums[i]).value=newNum;
     }
   }
  }
}