Showing results for 
Search instead for 
Did you mean: 

Fundamentals of VoIP Monitoring & Troubleshooting Part 1

Level 8

As a VoIP Engineer, I’m sure you’ve spent your fair share of time troubleshooting mysterious VoIP outages and call quality issues. You know, the ones that only happen when you’re not around and apparently only strike the most annoying end-user on the floor.

These kinds of problems can be very difficult to troubleshoot and provide root-cause analysis. Typically, troubleshooting the problem begins well after the fact and without any clues to help isolate the problem. This usually results in attempting to reproduce the issue by performing multiple test calls, checking the network for inconsistencies, and interrogating the end-user. If you’re the adventurous type, you’ll even go as far as installing your favorite packet capture software and reading through terabytes of captured network traffic, only to find that what sounded like a network issue is now gone without any trace.

Having a packet capture is very helpful when troubleshooting VoIP problems, but having them in the right place at the right time is a task easier said than done. If only there was a way to go back in time and place your packet capture between the end-user and the switch port prior to the call, surely you would have found the UDP errors or out of sequence packets that caused the garbled call. Unfortunately time travel is not an option, but do not despair. By enabling a couple of features on your Cisco® Call Manager and/or Avaya® Communication Manager, next time you’ll have the clues you need to isolate these problems without the guesswork.

Call Detail Records, CDRs, CMRs, and CQEs have many different names depending on the VoIP platform that you own, but they all provide very similar and useful call statistics. These include origin and destination of the call, starting time of the call, call duration, and termination codes. They also provide more important call quality statistics like jitter, latency, packet loss, and mean opinion score (MOS).

Each one of these metrics can have an effect on a call and, more importantly, can be used to isolate and resolve VoIP issues. In the second post of this four part series, I’ll cover each metric in more detail and explain what you need to look for when analyzing each while troubleshooting.

For more information on SolarWinds VoIP & Network Quality Manager watch our SE Guided Tour here.

1 Comment
Level 15

Educational and informative.  Thanks for the posting.