How Much Bandwidth is Needed for VoIP?


Companies are always looking for ways to improve their communication with customers, and VoIP has made that very cost-effective and easy to do. However, there are some things you must first evaluate when implementing your VoIP system. Assessing how much bandwidth is very important to do, as you will need to have internet speeds capable of handling large call volumes.

Related: Attach digital phone lines to your business phone system.

Bandwidth refers to the data transfer rate of your internet service. It essentially means the specific amount of data that you can transfer over your Internet service during a specific period of time. The bandwidth you receive from your Internet Service Provider (ISP) is important because you need to be able to allocate a certain amount to your VoIP service.

Since VoIP phone systems run entirely over the internet, your call quality will be directly correlated with your internet service and speed. If you have slower internet speed, or lower bandwidth, you may experience a drop off in call quality.

Bandwidth can impact VoIP calls in a multitude of ways, so to determine if your network can handle using VoIP, ask yourself these questions:

  • What is the upload and download speed you get from your internet service provider?
  • Do you run other applications or services on your network concurrently? If so, how much of your bandwidth do they use?
  • Does your network have Quality of Service setting that allows for you to optimize for VoIP?*

*Quality of Service settings allow you to prioritize certain types of traffic, such as voice, within your network.

Calculating How Much Bandwidth is Needed for VoIP

In order to accurately figure out how much bandwidth is needed for your business VoIP, you need to have a basic idea of how many concurrent calls you and your employees will be making. Typically, you will need anywhere from 85 - 100 Kbps per concurrent VoIP call. Keep in mind, the more browsing activity, the less bandwidth that is available for VoIP calls.

Another thing that determines the quality of your calls is which codec your provider is using. A codec is a program that essentially is used to convert voice signals into digital data that can be transmitted over the internet during your VoIP call. Different codecs have different sampling rates. Below, we have included a table for a better understanding of codecs. Before that, let's explain a few terms:

  • Bitrate per second: the rate at which bits of data is transmitted in a given amount of time
  • Lossless compression: Lossless compression rips your audio file so it is greatly reduced in size, but no quality is lost. In other words, it is a perfect copy.
  • Lossy compression: Reduces the file size up to 10x, but some audio data is permanently lost, so audio quality might be slightly compromised.
Codec name Average bandwidth required Description
G.729 8 Kbps 24 Kbps Uses an algorithm for extreme compression, works well with low bandwidth
G.711 64 Kbps 80 Kbps Offers lossless compression to reduce bandwidth needs, can be used for faxing as well
G.722 48-64 Kbps 80 Kbps High quality, but requires more bandwidth
G.726 16-40 Kbps 56 Kbps Used in international trunks
G.728 16 Kbps 32 Kbps Offers toll voice quality for lower bandwidths

AVOXI uses G.729 and G.711 codecs in their AVOXI Core platform, and an open-source codec called Opus for their new contact center software, AVOXI Genius. Opus has some advantages over traditional codecs:

  • Opus is open-source and free
  • Opus has features such as echo cancel to enhance calling experience
  • Opus is "intelligent" and supports variable bitrate encoding, from 6Kbps to 510 Kbps
  • Works very well in low bandwidth environments

Quality of Service and VoIP Phone Systems

As mentioned earlier, you need to make sure you have sufficient bandwidth to make high-quality VoIP calls. If you feel as if the quality of your calls is lacking, you can adjust your quality of service settings on your router. Most routers allow you to prioritize voice calls on your data network, which prevents other applications from affecting the call quality. If you’re not sure whether your router has this capability, contact your Internet Service Provider for more information.

Bandwidth and High Quality VoIP Calls

Your internet service (and bandwidth, specifically) are incredibly important to the success of your VoIP phone system. If you’re interested in making the switch to VoIP, talk to your Internet provider about your expected usage and work with them to make sure that your service can adequately handle your calls via VoIP phone numbers.