Switching to VoIP

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Interoperability

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To resolve the simulated incompatibility, remove the md5secret token from sip.conf

and attempt to place a call with the X-Lite softphone again.

Troubleshooting Quality-of-Service Issues

Not all troubleshooting situations involve signaling. As you may have read in prior

chapters, noise problems and dropouts stemming from jitter and packet loss are

cause for troubleshooting. Fortunately, the standards for sound transmission—RTP

and codecs—are simple compared to call signaling, so troubleshooting sound issues

is generally easier.

That’s not to say all sound-related issues are a snap to dismiss. Sound issues are

affected by many disciplines of networking: switching, routing, QoS, and packetiza-

tion. The way congestion on a routed link shows up is in dropouts, or in busy sig-

nals if you’re using a QoS solution. On a switched link, like Ethernet, busy signals

may occur long before dropouts are perceptible. So symptoms are different on differ-

ent links.

As with signaling, good diagnostic logging is valuable for troubleshooting. Packet

analysis is less useful when examining sound quality problems. One can certainly

identify jitter using packet capture, but it’s just easier to identify jitter across IP links

using tools like traceroute and pathping, which succinctly show ...