Summary

In this chapter we first had a 10 thousand mile overview of how VoIP works and why it is complex to diagnose (separation between media and signaling, firewalls, and NATs).

Then we looked at the various ways our flows can be interrupted, mostly due to internal LAN addresses wrongly sent as Internet reachable addresses, mismatching in configurations, packet-filtering and security devices not allowing network traffic.

A big part of the chapter was devoted to illustrating the practical usage of the best and latest network-tracing tools, both for capturing and visualizing VoIP packets.

Now you have all the tools and insights of the pros; now's the time to accumulate experience!