How to Reduce VoIP Latency: A Technical Guide to Testing Your Network

Have you ever been in a situation where you talked to your customer, and the call quality dropped suddenly?

Do your clients often experience choppy voices or echoes during the call?

If yes, then your business calls are suffering from call latency. You need to understand it and take care of it before it causes you a severe loss.

What exactly is latency?

Latency is a lag or delay between a user’s action and the response to that action. For instance, experiencing a delay after clicking to view an online video is called latency. It takes a few milliseconds for data to transmit from one location to another.

What is Latency in VoIP?

In terms of virtual phone systems, latency refers to a bit of delay when audio data transfers from one phone system to another.

When latency occurs, the person on the other end listens to your words a few milliseconds (ms) later. Latency also causes “glitches in” invoice data. It muddles someone’s voice or overlaps two peoples’ voices.

What is acceptable latency for VoIP?

VoIP users often deal with some form of latency. Since VoIP uses the Internet to transmit data.

However, voice latency is acceptable upto a specific time.

According to a VoIP leader like Cisco, 150 milliseconds (ms) is a normal, acceptable latency for VoIP systems. It means when you speak during the call, it must not take more than 150 ms for the listener to hear you.

Businesses should not suffer notable lags or jumbled voices in the middle of each call. Extreme latency becomes a big issue for one-on-one conversations and also decreases the quality of real-time communication.

How Can Latency Affect Your Business?

VoIP latency is more of a trouble for your business since voice calls are real-time communications, and even a slight delay or miscommunication may result in losing clients.

A decade ago, Amazon noticed that each 100ms of latency cost them 1% in sales.
(Source: Gigaspaces)

Besides, there are other issues caused by slow data transmission:

  1. Slow-moving conversations dropped calls and interrupted talks where one speaker disturbs the other’s unknowingly (a.k.a. Overlapping noises).
  2. Echoes make it hard for the listener to differentiate between spoken words.
  3. It worsens with one or both callers having different accents—a typical case with international business calls.
  4. High latency triggers serious issues during one-to-one calls, but these problems aggravate multiparty conference calls.
  5. Out of sync, audios can quickly send project meetings off the rails.
  6. Slow download and upload speeds
  7. Internet connection issues
  8. Loss of real-time interaction
  9. Static, uneven, garbled, and puzzling audio

Because of these reasons, you must take latency seriously and ensure low latency for high-quality voice calls.

What Causes Latency and how do you fix latency issues ?

So, what causes VoIP latency, and how can you fix it?

There are various reasons for latency in your virtual phone system, and most of them are factors you’d never believe can have a significant impact.

Below, we have mentioned some common reasons for the lag or delay and offer actionable advice to fix it.

1. Big gap between servers

Sometimes, latency occurs due to a significant distance between the server/system that requests and responds to it.


Make sure your VoIP service provider offers various national and international IP addresses and server locations. The more data centers your service provider has, the more likely you’ll attain low latency levels.

2. Insufficient Bandwidth

VoIP transforms your voice into a digital signal that shifts into data packets. These packets travel through the Internet and arrive at the call recipient.

Bandwidth refers to the maximum data your Internet connection transfers within a specific time (note that it doesn’t include your Internet speed, only the amount of data it can transmit from one place to another over a set timeframe.)

Insufficient bandwidth—low capacity of your connection to handle immediate data needs—increases the latency figures.

For instance, the busiest hours of the day cause network congestion, a situation where it carries so much data that it decreases network service quality. As a result, your data experience delays in reaching the intended destination.


If you use a VoIP phone system, it’s time to upgrade your bandwidth to prevent delays or increased latency. Your bandwidth requirements depend on the number of concurrent calls your organization makes.

Bandwidth is measured in MBPS (megabits per second). 12-25mpbs is an average bandwidth.

3. Outdated Hardware

Your internal network is a house of numerous physical hardware components. Physical firewalls, analog to digital converters, session border controllers, network cables or fiber optics, routers, modems, lines, switches, and all other WiFi parts get together to create your network.

Tell me, when was the last time you upgraded any of this hardware?

Outdated hardware faces physical limitations such as a shortage of ports to plug-in devices, a damaged port, or an antenna wrestling. Such defects cause packet loss. Meaning the packets carrying the information are left behind or get lost to make the network catch up.


Make sure your hardware is up-to-date and not damaged. Consider using VoIP routers especially made for virtual phone systems.

Also, thoroughly inspect your cables, wires, modems, and ports, ensuring they are not bent or damaged. And if you are using old-age headsets or microphones, maybe you need to replace them with modern ones.

4. Internet Connection, ISP Quality, or VoIP Provider Issues

Sometimes, the problem takes place from your VoIP or Internet Service Provider (ISP).

Let’s say your ISP uses a codec (a device compressing and decompressing data in VoIP) that’s not compatible with your VoIP system. Thus, network lag occurs as the devices can’t appropriately interact with the network.


Request your provider to shift to a compatible codec. If that’s not possible, you’ll have to change your Internet Service Provider. Make sure your network connection is correctly configured, and all Ethernet cords are plugged in.

Also, contact your VoIP provider to ask if they can offer any troubleshooting tips. Chances are, they fix such issues often.

5. Configure QoS (Quality of Service)

Companies using the Internet for multiple devices have Quality of Service (QoS) settings. It allows you to prioritize bandwidth for some devices and data. If you are experiencing VoIP latency during phone calls, it means you are not prioritizing your VoIP system.


Set your VoIP system first in the line of your bandwidth usage. Prioritize VoIP traffic over other data. It will avail more bandwidth for your frequent calls.

6. Take Care of Jitter & Buffer

Network jitter is an issue where a connection faces irregular delays between data packets.

Buffering happens when there’s a difference between the audio data transmission and reception time.


A jitter buffer is a convenient device installed on a VoIP system. Jitter buffering delays VoIP audio enough to rearrange voice packets correctly. This process makes sure the incoming voice packets reach in order with minimum delay.

If your VoIP system offers a jitter buffer facility, set it up under 200 milliseconds.

7. Extra tips to Reduce Latency

If nothing works, you could give a try these tips:

  • Change your Firewall or other antivirus software settings to open ports and permit VoIP software.
  • Disable unused applications and disconnect devices not in use.

How to Measure Latency?

Now you have a better understanding of what VoIP latency is and why it matters. You need to take one final step to identify the underlying latency and fix it.

Measuring your latency.

Latency is measured in milliseconds (ms). These are thousandths of a second.

20 ms is a normal latency for VoIP calls. 150 ms is hardly recognizable and hence acceptable. Anything more than that is a serious problem. For instance, over 300 ms latency starts diminishing the quality.

You can measure latency in two ways:

  • One-way latency: the time a packet takes for one-way travel—from the actual source to the destination.
  • Two-way latency (a.k.a. round trip time latency): the time a packet takes to travel back and forth—from source to the destination and back to the source.

Network latency testing, also called a ping test, helps you understand the amount of lag you’re dealing with in your VoIP phone system. It even assists you in determining other issues impacting your business call quality.

You can use a VoIP and Internet Speed Test Tool to measure your latency.

Crystal-clear voice quality in front

Simple solutions have a massive impact on business voice calls. Implement the tips mentioned above and make sure your virtual phone systems help your business succeed, not suffer.

Still, have a few questions?

Get in touch with Cebod Telecom, one of the most reliable VoIP service providers for businesses. Our VoIP service experts help you reduce latency and walk you through each step, ensuring premium call quality backed by incredible services on time.