Troubleshooting call quality issues
Choppy line, dropped calls, voice delay, garbled
• Network congestion/delay leading to dropped packets (Local Area Network (LAN) related issues)
• Lack of bandwidth/unable to support simultaneous calls (Internet Service Provider (ISP) related issues/ Internet connection issues)
• Inconsistent ISP/throughput performance (ISP/ Internet connection issues)
How to resolve:
• Isolate the issue
• Are you the only one experiencing this or is it affecting other phones?
• Any recent changes to your local network? Changes may include the following:
• added a file server to the local network
• added/changed a network switch/router/firewall
• changed Internet Service Provider
• If there are no recent changes, follow the suggestions below:
1. Check the performance of your Internet connection
• Slow internet connection - If browsing websites is slow,
- contact your IT Administrator, or your Internet Service Provider (ISP) to check on your internet connection.
• Able to connect to the internet fine (i.e. to websites and data services),
- run 3 to 4 consecutive speed tests via www.speedtest.net
, to measure the performance of your Internet connection.
- the performance may have been degraded to a point where it is contributing to ‘packet loss’ and/or ‘jitter’, which in turn will affect call-quality performance;
- voice traffic is highly sensitive to network performance degradations.
What to look for in the speed test results?
• To make use of the results, you will need to know what your provisioned bandwidth/speed is; that is what bandwidth/speed are you paying for when you signed up with your ISP. The speed test results will show the following 3 parameters:
• The Ping results reflect the overall delay in the network.
• The Ping results should be under 60ms;
• normal can range anywhere between 5ms to 48ms, as it depends on your connection with the ISP.
• The Download/Upload results should be no less than 75-80% of your provisioned speed.
• Perform 3 to 4 consecutive speed tests noting consistency in the result, and that the performance is not fluctuating 20% (increase or decrease).
• If you are getting inconsistent results or if your Actual speed is 75-80% less than your provisioned speed, you may need to contact your ISP to check the performance you are seeing vs what you are paying for.
• If possible, determine options to get a Business-level service agreement with your ISP. You may have to pay a bit more for the service, however it will ensure that they provide to the level of performance you are paying for consistently.
2. Set your Router to Prioritize Voice-related Traffic
• Ensure that ‘prioritization’
is configured for the voice-related traffic AND
• that a ‘minimum guaranteed bandwidth’
for this prioritized traffic is set, on your router/firewall.
In most Small Office Home Office (SOHO) routers, these QoS-related features are located in the QoS/Traffic Manager section of the router. Consult the manufacturer of your router for instruction on setting up the prioritization.Recommended Routers Optimizing the Dell SonicWALL SOHO router to deal with QoS