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Mar 28

How To Survive VoIP Troubleshooting

Before we talk about troubleshooting, let’s take a minute to consider making sure you’ve chosen the right VoIP provider prior to signing the contract. It’s essential to be comfortable with the technology, configuration, and benefit to your business, however the most important evaluation is how the service provider will support your system moving forward. If you make the right decision and choose the right vendor, troubleshooting will be a much easier process. Ask these questions before you sign on the dotted line:

  • How do existing clients rate the overall performance of the VoIP service, equipment and customer service?
  • Does the VoIP provider offer a 24/7 technical team providing engineering support?
  • What are the service level agreements?
  • What is the escalation process for managing timely trouble resolution?

If you can’t answer these questions, we recommend you speak to your potential or existing VoIP provider to dig deeper into the customer support you can expect.

Now, on to the details of how you survive VoIP trouble resolution and where to start. VoIP converts the sound of your voice into thousands of packets, and many design components can affect the packet transport, impacting the call quality. The three most common issues that affect call quality are Latency (Delay), Jitter (Timing), and Packet Loss. Each issue originates in your ISP’s network access and performance (WAN), your local supporting infrastructure (LAN), or your VoIP service provider’s call processing and call management. In order to efficiently diagnose the root cause of a problem, we evaluate three (3) primary areas: Network and Broadband, Local Area Network Infrastructure, and Electrical and Noise Interference.

Network And Broadband

Bandwidth can often be the source of several issues related to a VoIP system because of the direct relationship to network latency, jitter and packet loss. If a call sounds distorted, has an echo or the calls are choppy, it’s because of latency and jitter, which is a delay in the delivery speed of your bandwidth. Dropped calls also can be a symptom of network packet loss. The transport of voice packets differs from “old fashioned” analog voice. VoIP requires an additional set of internet protocols that your ISP should be providing.

  • Start by asking your ISP to analyze your network speeds which will determine the amount of data lost when transmitting through the network. Any of these call quality symptoms can result from network congestion.
  • Make certain you keep a record of the exact call, telephone number, and time, so the ISP and VOIP providers can test the call examples as part of their diagnostics.

The real question is where is the network congestion? Is it on the ISP’s side or is your internal company network experiencing congestion?

  • Your ISP may experience periods of latency and jitter because of routing during certain times of the day or utilization on-site.
  • Reliance on WiFi versus a direct network connection also can be a cause latency. The speed and connection are not as robust as direct connections.
  • Employees using streaming applications which are “bandwidth hogs” can limit bandwidth for other applications and is worth investigating.

Local Area Network (LAN) Infrastructure

It’s not always the VoIP/ISP’s problems that cause call quality issues. Remember, your network has a lot of important electronics and cabling/inside wiring at your location. Regular inspection and monitoring of this ecosystem is a requirement. Problems limited to a few users often originate in the equipment and connections at your location. Start the troubleshooting process with the end-point (VoIP phone) through to the port in your switch.

Follow the logical path through the equipment and connections to the ISP network.

• VoIP Phone:

o Recycle the phone from the associated power source.

o Connect the phone directly to the network eliminating any pass-through device such as a computer.

o Test the jack and cabling by connecting a working phone to make sure it’s not defective or has a configuration problem.

• Cable:

o Loose, crimped or damaged cable connections can cause sporadic problems for one or more end users.

• LAN Cable:

o Ensure there is a network connection to the Modem/Firewall, Router, Switch, and each component is connected in the correct order.

o If wireless access is part of the network experiencing problems, reset and test the access points.

• Modem/Router/Firewall:

o Ensure SIP/ALG is disabled

o Reset your router if required.

o Review the router’s configuration which is the basis or plan for your VoIP call quality and experience.

o Assure you have selected the Quality of Service (QoS) features to help optimize the data traffic and prioritize the voice traffic.

  • Verify the ports that the VoIP provider requires to be open for traffic.

• Network Switch:

o Verify the network jack supporting the VoIP phone correlates to the same port number on the switch.

o Test the port in the switch to establish continuity.

Electrical And Noise Interference

Although electromagnetic interference is not as common today as it was many years ago, it is still a factor that causes your network to experience a degradation of service. The degraded service could include typical call quality issues and overall performance failure.

o Try turning off other computers connected to your network, to test for added noise, or network congestion.

o Review any additional devices such as micro switches or splitters not part of the initial design, which may require unplanned bandwidth.

o If the VoIP hardware or cabling is too close to other electrical devices or wiring, electromagnetic interference is a possibility. 

Troubleshooting is about starting with simple, easy fixes and working your way up to the more complex testing. With VoIP, several areas may affect service continuity and the quality of the service. Keep these four (4) simple questions in your back pocket and start here:

1. Are all services affected or just voice?

2. Are all users affected or just a few?

3. Is everything plugged in and turned on (endpoint, computer, switch, router, modem/firewall)?

4. Did you reboot/reset the endpoints, and infrastructure electronics?

These simple questions will save time and help you determine where the problem is likely located. You’ll find that a high percentage of your trouble reports will be solved very quickly by having the end user or your tech answer these easy questions and perform these simple tasks. All technologies experience occasional problems, but your preparation and choice of the right VoIP service provider will pay consistent dividends by reducing downtime and business interruption.

About The Author

Zina Hassel is President and Founder of ZLH Enterprises and has been a member of The ASCII Group since 2015.

About The ASCII Group, Inc.

The ASCII Group is a vibrant reseller community of independent MSPs, VARs, and other solutions providers. Formed in 1984, ASCII has more than 70 programs that provide turnkey cost-cutting strategies, innovative business building programs, and extensive peer interaction. ASCII members enjoy benefits such as marketing support; educational information; group purchasing power; increased leverage in the marketplace; and multiple networking opportunities. These programs enable ASCII members to increase revenue, lower operating costs, and grow service opportunities. ASCII is the oldest and largest group of independent information technology (IT) solutions providers, integrators and value added resellers (VARs) in the world. Learn more at

About The Author

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