One place I do tech work for have POS's that require Net access because part of the services link into API's for UPS, FexEx, and USPS for realtime transactions. The POS software and shipping software get updates regularly, whether it be bug fixes, feature improvements, or shipping rates updates. The POS, also, can links into a noreply email to send people invoices and tracking. Safe guards: being placed on a separate isolated network from the main one, strict firewall settings, intrusion detection, and a good host file. CCs are not processed on them at all, since there are handled by dedicated machines from merchant services on a dedicated landline.