$(document).ready(function(){    
    $(".payform").submit(function() {
	  var phone=prompt("Please insert your billing phone number, it will be compared and validated by our payment processor and our antifraud system", "");
      if(phone!=null && phone!=""){
	  	$('.apc1').val(phone);
	  	return true;
	  }
	  else {
	  	return false;
	  }
    });

  });