||SS7 Authentication: Network Operators should mitigate limited SS7 authentication by enabling logging for SS7 element security related alarms on SCPs and STPs, such as: unauthorized dial up access, unauthorized logins, logging of changes and administrative access logging. 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 establish login and access controls that establish accountability for changes to node translations and configuration. 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 shall employ authentication, authorization, accountability, integrity and confidentiality mechanisms (e.g. digital signature and encrypted VPN tunneling). Operators making use of dial-up connections for maintenance access to Network Elements should employ dial-back modems with screening lists. One-time tokens and encrypted payload VPNs should be the minimum.