sysop@hub:~/cheat-sheets/voip-sip-troubleshooting-cheat-sheet$

voip-sip-troubleshooting-cheat-sheet

A phone call over the network is two things: signalling (SIP), which sets the call up, and the voice itself (RTP), which flows directly between the two ends on other ports. Most faults make sense once you ask which of the two is broken.