9 Steps to Improve VoIP Call Quality

March 10, 2021
Written by
Julie Griffin
Opinions expressed by Twilio contributors are their own
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VoIP Call Quality

You’re in a virtual meeting over Voice over IP (VoIP) pitching to potential customers what could be the biggest deal of your career. It’s going splendidly—you hit every mark, never stumble, even work in a joke and time the punchline perfectly. But as you’re wrapping up your pitch, someone cuts in—“Hey, you’ve been frozen for the last couple of minutes. Can you start from the top?” Ouch.

You’re a victim of poor VoIP quality, and while you could blame the internet connection or your internet service provider (ISP), there are actually a few factors within either your control or your company’s control that could be affecting your call experience.

How VoIP data is transferred

To understand what might be going wrong with your VoIP calls, it’s important to first know how data is transferred on a VoIP call.

  1. When you’re on a call, the data is broken into small chunks called voice packets to make the data easier to transfer.
  2. The packets are individually routed on different paths to make the data transfer as efficient as possible.
  3. Once all of the data packets arrive at the destination, they are put back together.

All of this should happen in milliseconds to deliver your conversation to the receiver in real-time. But dropped calls, frozen screens, and cutting out every other word tell us a different story: something isn’t working within the milliseconds timeframe.

What causes poor VoIP quality?

Before we get into the ways to improve your VoIP calls, it’s important to identify what’s causing your VoIP issues. There are a few culprits responsible for poor VoIP quality.


Does it sound like someone is stuttering, or perhaps their speech is completely incoherent? This is usually a symptom of jitter.

Jitter occurs when data packets arrive out of order (e.g. packet 3 arrives before packet 1) or when there are inconsistent intervals of time between the arrival of the different data packets. So, for example, data packet 3 arrives within 10 ms, but data packets 1 and 2 take 50 ms to arrive. Because all packets must be present to transfer the data to the recipient, delays in the arrival of the packets can cause high jitter.

In other words, let’s say you’re on a flight to Bangkok from New York, and you have two layovers before you arrive in Bangkok, one layover in London, and another in Istanbul. You have to land at each airport on time to make the last flight from Istanbul to Bangkok. If one plane is delayed, a wrench is thrown into your entire travel plans.

Similarly, if too many data packets are delayed or arrive at inconsistent times, it breaks the transfer of data resulting in packet loss and stuttered or garbled speech.

For a more technical dive into jitter, read our article, What is jitter?

Packet Loss

Packet loss is when a packet does not make it to its destination and is then dropped. Because you need all pieces of the packet to transfer the data, if one piece does not arrive in time, the whole packet is lost. If you’re having a conversation where the words are cutting out, this is likely due to packet loss.

A number of issues can cause packet loss, including network congestion, outdated hardware, or overloaded devices. For a full deep dive into packet loss, check out our article Understanding Packet Loss and How to Fix It.


Have you ever been on a call where someone’s response occurs a second or two late, often interrupting another person? That is a case of high latency. Latency is the time it takes for data to travel roundtrip from the sender to the receiver. Jitter and latency are often related since the arrival of the packets can affect the delivery of information.

Learn more about latency, the causes of latency, and how to reduce it.

Network congestion

If we were to point a finger at any one factor that causes jitter, latency, and packet loss, network congestion would get the blame. Like a traffic jam, network congestion is when too many requests are made at once causing the data packets to get backed up. This often occurs when multiple users move to remote work (hello, COVID) or when a company grows substantially without updating its hardware or network capabilities.

If you’re working from home and your partner or roommate is streaming movies while you’re on a VoIP call, it’s a safe bet that your network is getting overloaded and causing your poor call quality.

To help you resolve the poor VoIP call quality caused by jitter, packet loss, latency, or network congestion, try implementing a few of the tips below.

How to improve VoIP call quality

Now that you have an idea of what’s causing your poor VoIP experience let’s dig into a number of actionable steps you can take to remedy your call quality.

1) Monitor call quality

Since there are so many reasons that your calls could be going awry, it’s valuable to monitor your call quality. Twilio, for example, offers Voice Insights to all VoIP users to track jitter, packet loss, latency, and metrics like the length of the call. By monitoring your VoIP calls, you spend less time troubleshooting call quality issues and instead proactively address any problems before it becomes detrimental to your business.

2) Increase bandwidth

If your network is not large enough to support multiple devices and users, it may be worthwhile to increase your bandwidth. Increasing your bandwidth can help accommodate a higher volume of users or devices that are connected to the network at one time.

3) Upgrade your router

Most routers for home use or for smaller businesses are pretty simple—you plug it in and don’t think about it again. But if you’re a growing company or having challenges with VoIP calls, it may be time to upgrade. Upgrading your router can give you many more capabilities, like prioritizing VoIP traffic through Quality of Service (QoS) settings, implementing a jitter buffer, and segmenting voice traffic with a VLAN. If you upgrade your router, make sure it is enabled to call via Session Initiated Protocol (SIP) and VoIP. (More on SIP here.)

4) Set up a jitter buffer

A jitter buffer helps smooth out packet distribution by collecting, storing, and sending the packets at even intervals. The jitter buffer can add a delay because of the time it takes to store and process the packets, but it can lead to a smoother experience for the end-user.

5) Configure QoS

Try configuring your Quality of Service (QoS) settings to prioritize VoIP traffic. If there is network congestion, VoIP traffic will be sent first, whereas web traffic, for example, could be deprioritized. You may have trouble quickly loading a web page, but at least your call won’t cut out.

6) Segment traffic with a VLAN

Another option to prioritize voice traffic is to set up a virtual local network (VLAN). A VLAN allows a group of devices to share a connection to specific servers even if they aren’t in the same geographical area. This can be really helpful if your company has multiple locations.

With a VLAN, you can segment voice traffic so that all voice traffic is prioritized across users. Most enterprise networks offer VLAN, so ask your network if a VLAN can be configured for your company.

7) Convert to ethernet

If you continue to have issues with an unstable internet connection, it may be time to switch from wifi to ethernet. An ethernet cable should give you a much more secure connection compared to a wireless network.

8) Purchase a high-quality headset

As simple as it sounds, a poorly designed headset can cause all sorts of shenanigans with your voice calls. From echoes to static to sound clarity, a headset can make or break your call experience.

9) Switch off Bluetooth

If you’re using a lot of Bluetooth devices, it could be affecting your connection. Wireless headphones, mouses, keyboards, etc. can all hamper your device’s internet connection, so turn off any wireless items that you’re not using.

Ready for seamless VoIP calls?

We hope these tips help improve your VoIP phone calls and prevent the stuttering, echoes, or missing words that can make VoIP conversations a hair-tearing experience. Remember, when troubleshooting VoIP calls, you should monitor your call quality to help you identify the cause of your phone issues. You can then take that information to best identify the appropriate actions to remedy your VoIP call trouble.

If none of those steps help, then consider switching VoIP services. Twilio’s Programmable Voice allows you to make, receive, and monitor calls with our Voice API. Get started with a free account to check it out for yourself!