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VoIP Troubleshooting: Common Problems and Easy Fixes

July 26, 2023
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Businesses of all sizes are now leveraging the Internet to make communication more cost-effective and convenient. Employees, managers and entrepreneurs are no longer bound to desk phones. Instead, they handle calls from their laptops, desktops and mobile devices through a Voice Over Internet Protocol (VoIP) service account.

VoIP communication models have many advantages over the traditional PBX systems, but sometimes there are challenges. Nearly 70% of businesses using VOIP technology have experienced a problem of some sort, usually linked to their internet. The good news is that many problems commonly faced by VoIP users can be easily fixed. Let's take a closer look.

Table Of Content
  • What is VoIP and how does it work?
  • What are the tools available to diagnose and resolve VoIP problems?
  • Troubleshooting common VoIP problems
  • Solving Audio Latency Issues in VoIP Calls
  • Fixing VoIP Service Outages and Dropped Calls
  • Optimizing VoIP Bandwidth Usage for High Call Volume
  • Troubleshooting VoIP Integration with Other Business Systems
  • Solving echo problems in VoIP calls
  • VoIP security concerns and troubleshooting
  • VoIP call setup and configuration troubleshooting

What is VoIP and how does it work?

VoIP services rely on connectivity through the internet. Subscribers can make and receive voice and video calls, exchange messages and more through this communication service.

Unlike traditional phone connections, VoIP accounts are not linked to a device but rather to a number. This number can be accessed through different devices with working internet connections. When a call is made through a VoIP account, the speaker's voice is digitized from its analog form and transmitted over the internet to the receiver.

When compared to traditional phone services, VoIP subscriptions are more flexible, cheaper, more secure and easier to scale. Over 80% of businesses using VOIP technology have reported cost savings compared to traditional phone systems. Depending on the service provider and the subscription model chosen, a VoIP account can also be inclusive of many productivity-enhancing features such as call monitoring, call transfers, call recording, call routing, etc.

What are the tools available to diagnose and resolve VoIP problems?

Issues with VoIP connections often take the form of inaudible segments in a conversation, call drops, echoes, etc. When faced with such issues, there are a number of tools you can use to understand the cause of the problem and its scope. Some of these tools are:

Ping Test

Let's get technical! A Ping test is a simple tool that helps identify where your network may have an issue. It involves sending an Internet Control Message Protocol (ICMP) packet to the desired destination. These packets have very low bandwidth requirements. Once it reaches the destination, the ping request is recognized and replied to. Ping test results such as the total time taken to receive a reply, packet loss, jitter and latency, etc. indicate your network performance.

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Internet speed test

As the name suggests, an internet speed test checks the speed, latency and jitter of your internet connection and shows you the bandwidth available to handle VoIP calls. The more bandwidth available to you, the faster your calls can be connected. When it comes to business accounts, bandwidth also determines the number of VoIP calls that can be handled simultaneously.


If you're facing jumbled audio or can't hear the other person in between a call, it could be because of packet loss. In such cases, traceroute tests can help identify the potential issue with your internet connection. This test logs all the intermediary points along which a packet is transmitted and how long it takes to move from one point to another. This helps visualize speed inconsistencies.

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Troubleshooting common VoIP problems

While the tests listed above may help identify where your internet connection is facing a problem, they will not help resolve them. Before you call the customer service team, here are a few things that can help.

Identifying VoIP connectivity issues

If you're not satisfied with the audio quality of your calls or see calls being dropped often, it may be because of inadequate bandwidth.

The first thing you need to do is check your internet connection. Make sure your router and modem are working correctly. Then check your internet speed. If the problem persists, you may need to upgrade your network hardware.

Troubleshooting audio quality problems in VoIP calls

Over 50% of businesses experience poor call quality with VOIP systems. The other person's voice may be muffled, they may be inaudible, there may be a buzzing sound in the background and so on. This can be frustrating for the customer trying to explain their problem as well as the business representative trying to understand the query.

An easy solution is to check your bandwidth usage and ensure that other devices are not using up too much bandwidth. Another solution would be to adjust the CODEC settings in the VoIP software being used.

Solving Audio Latency Issues in VoIP Calls

Latency in a VoIP call or the lag in transmission is measured as milliseconds or ‘ms'. Latency higher than 150ms can have an adverse effect on call quality. Latency can be influenced by distance from the data center, network hardware, wireless network strength, network configuration as well as congestion.

Some of the steps you can take to troubleshoot latency issues are:

  • Check hardware for damage and make upgrades
  • Configure the router's Quality of Service settings to prioritize VoIP calling
  • Disconnect unnecessary devices from the Wi-Fi network

Fixing VoIP Service Outages and Dropped Calls

Dropped calls can be a major business issue. No business can afford to have its customers assume that they hung up on them. You may notice calls being dropped after a fixed length of time or when your volume of outbound calls increases significantly.

To troubleshoot dropped calls here are a few things you can do:

  • Check your network settings
  • Ensure that your router is configured correctly
  • Check that your firewalls are not blocking VoIP traffic
  • Adjust your NAT settings
  • Disconnect all devices and reconnect them one at a time to see where the problem lies
  • Turn on auto-updates for your device firmware
  • Check your settings to ensure your calls are not set up to be disconnected after a specific time

Optimizing VoIP Bandwidth Usage for High Call Volume

Your internet speed or bandwidth and network configuration also influence VoIP call quality. Some internet bundles may be good enough for surfing the net but not powerful enough to handle voice and video calls. If the bandwidth is insufficient, calls may drop expectantly when you have a high number of calls being handled. Here are a few ways to optimize your bandwidth:

  • Upgrade your internet subscription – you need to have at least 100kbps bandwidth
  • Switch from cable internet to fiber-optic internet
  • Create a VLAN that prioritizes voice packet transfers
  • Invest in switches with auto-configurations and high throughput gigabit ports

Troubleshooting VoIP Integration with Other Business Systems

Integrating a VoIP system with other existing business systems such as CRM software or calendars makes multitasking easier, improves efficiency and aids in data management. Issues related to integration can be resolved by:

  • Use high-speed VoIP routers or ethernet cables
  • Ensure the system is set up correctly
  • Ensure standardization of data units and formats

Sometimes, problems with integration can be indicative of missing skills. Users may be unfamiliar with it. Here, training modules can help.

Solving echo problems in VoIP calls

Hearing an echo on your VoIP calls may also be referred to as a latency issue. It means that the voice packets being transmitted are traveling at different speeds and arriving at different times and sound levels. In many cases, only one person is aware of this echo. An echo may be caused by issues with the device or the network.

Some simple tips to solve the echo problem are:

  • Make sure your hardware is not damaged
  • Adjust the volume of your Bluetooth headset
  • Get more bandwidth
  • Ensure there are no other electronic devices such as non-LCD televisions or light fixtures emitting electromagnetic interference

Network and Lan issues can cause problems such as one-way audio, choppy voice or not putting calls through. These issues are usually centered around poor connections between the equipment being used and the internet. Here are a few troubleshooting tips:

  • Unplug and reconnect your LAN router
  • Disable forward ports
  • Install firmware updates for the router
  • Upgrade to a router that prioritizes VoIP calls over other network traffic

In many cases, poor audio quality and call drops aren't because of network issues but rather because of the hardware being used. Your handset or Bluetooth device may not be updated to the latest version or be damaged.

Testing and replacing your audio devices may help. Or, you may need to update your device software. Adjusting the volume of your earpiece may also help. Sometimes, the solution may be something as simple as a device not being plugged in properly.

Handling fax and modem issues with VoIP

VoIP systems can be used for faxes but faxing over VoIP is known to be troublesome. This is mostly because faxes cannot be compressed for digital transmission over the internet and hence it uses up a lot of bandwidth. There may also be mis-matched settings between fax machines.

You can try optimizing the network settings to give you the bandwidth required for fax transmissions or slow down the transmission speed. You can also try disabling Error Connection Mode (ECM). Alternatively, switch to a cloud fax model.

Inability to make calls with VoIP

As with any other communication system, you need your VoIP system to be set up to make and receive calls. Being unable to make outgoing calls can be quite problematic for customer support and sales teams. The issue here is most likely to be linked to your network layout. To solve it, you could try these tips:

  • Check your internet connection
  • Disable the SIP ALG
  • Make sure the flow of data is not being stopped by a double NAT
  • Connect your VoIP devices to a Virtual Local Area Network (VLAN)

VoIP security concerns and troubleshooting

From vishing attacks to having your server intentionally overwhelmed with data, there are many security risks VoIP subscribers need to protect themselves from. The best thing to do is to stay updated about the fraud schemes and security vulnerabilities being leveraged by fraudsters and conduct regular security audits. In addition, you can mitigate the damage of such security issues by:

  • Choose a VoIP service provider with an encryption service for all calls
  • Maintain reserve bandwidth for emergency situations such as DDoS attacks
  • Set up a strong network firewall
  • Use a verification system to validate all incoming calls
  • Track off-hours usage spikes

VoIP call setup and configuration troubleshooting

Issues connected to call setup and configuration can keep calls from being connected, connect calls without transmitting any audio and lower call quality. Here are a few troubleshooting tips that may help:

  • Check your internet connection
  • Change the SIP registration port on the VoIP device and reboot
  • Change the SIP server name and reboot
  • Make sure you are using the right account number and password
  • Make sure multiple devices are not using the same SIP and RTP ports
  • Disable your firewall temporarily
  • Enable the DMZ option on the router to open the firewall for your VoIP device

Conclusion: Tips for Successful VoIP Troubleshooting

When done right VoIP communication can be a game changer for businesses. As with any other system, adopting this technology has its own challenges. That said, the frequency of service outages and other such connectivity issues is one of the key factors to be considered when comparing VoIP service providers.

Choose a service provider known for resilience, ease of usage, good connectivity and reliable customer service. Along with the presence of a customer support team, make sure you have easy access to them – some service providers limit your ability to reach out to customer service teams only through emails or web forms. When you're facing a problem, you need to be able to pick up the phone and speak to a service representative.

After all, if your call quality is still low or you're unable to make and receive calls, you will need to ask the service provider to look into the matter. If the problem can be solved at your end, they can guide you through troubleshooting steps to identify the root cause and rectify it. Or, it may be a problem that doesn't affect just you and is something they need to handle at their end.