Comrex BRIC-Link II, Product Manual

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The second op on, which u lizes the outgoing Directory Server “ping” described earlier, is very useful. The interval
of this ping is adjustable, but defaults to about one minute, which is short enough to keep a hole punched through
the majority of NAT routers.
These techniques are based loosely, with enhancements, on a generic internet protocol called STUN (Simple
Traversal of UDP through NAT). The system works well in all environments except one: when both users are si ng
behind a symmetric NAT. In this situa on, calls will fail even with Switchboard. The only op on in that environment
is to resort to port forwarding on one side of the link.
Overall, Switchboard takes the complexity of interac ons between public and private internet and translates the
user experience into a simple point-and-click methodology, giving Comrex codec users more freedom with less
e
ff ort.