The Global Service never attempts to contact a NextPage client. Instead, each client periodically polls the Global Service (via HTTP/80) to check whether it has a message to retrieve. If there is a message, it conducts a secure conversation (via HTTPS/443) to pull the message. Similarly, if the client has information to push, it does so securely (via HTTPS/443). Because messages are always outbound from a NextPage client to the Global Service, the system is compatible with network address translation (NAT), which has become de rigueur for private networks. The NextPage products also uses standard ports (80 and 443), eliminating the need to open non-standard ports in the firewall. | 
