function IsNumeric(strString)
   //  check for valid numeric strings	
   {
   var strValidChars = "0123456789";
   var strChar;
   var blnResult = true;


   if (strString.length != 10) {
         alert ("You must enter a valid 10 digit number.");
		 return false; 
		}
   if ( strString.charAt(0) != 0 ) {
		 alert ("You must enter area code begining with 0");
		 return false;
    }


   for (i = 0; i < strString.length && blnResult == true; i++)
      {
      strChar = strString.charAt(i);
      
      if (strValidChars.indexOf(strChar) == -1)
         {
         blnResult = false;
         }
      }
   }