||Network Access Control for SS7: Network Operators should ensure that SS7 signaling interface points that connect to the IP Private and Corporate networks interfaces are well hardened, protected with packet filtering firewalls; and enforce strong authentication. Similar safeguards should be implemented for e-commerce applications to the SS7 network. Network Operators should implement rigorous screening on both internal and interconnecting signaling links and should investigate new, and more thorough screening capabilities. Operators of products built on general purpose computing products should proactively monitor all security issues associated with those products and promptly apply security fixes, as necessary. Operators should be particularly vigilant with respect to signaling traffic delivered or carried over Internet Protocol networks. Network Operators that do employ the Public Internet for signaling, transport, or maintenance communications and any maintenance access to Network Elements should employ authentication, authorization, accountability, integrity, and confidentiality mechanisms (e.g., digital signature and encrypted VPN tunneling).