Require phone numbers on Chargify hosted pages.

chargify-require-phone.js

// Past into the custom javascript field for your hosted page to use javascript to require phone numbers.

var phoneLabel = jQuery('[for=subscription_customer_attributes_phone]');
phoneLabel.text('* Phone')
phoneInput = jQuery('#subscription_customer_attributes_phone');
jQuery('#hosted-payment-form').submit(function(){
  if(phoneInput.val() == '') {
    phoneLabel.text('* Phone: cannot be blank.')
    phoneLabel.css('color', 'red');
    phoneInput.click(function(){
      jQuery('#subscription_submit').removeAttr('disabled');
    });
    return false;
  } else {
    return true;
  }
});