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VoIP Bandwidth/Traffic Usage

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VoIP Bandwidth/Traffic Usage
Photo by Taylor Vick / Unsplash

Voice over Internet Protocol (VoIP) systems are known for their efficient use of bandwidth. Unlike traditional telephone systems that require dedicated circuits, VoIP digitizes voice signals and compresses them into data packets. This compression significantly reduces the amount of bandwidth needed for voice communication. On average, a VoIP call consumes around 100 kbps (kilobits per second) of bandwidth, making it feasible even on modest internet connections. However, the actual bandwidth usage can vary based on factors such as the codec used, call quality, and additional features like video conferencing.

It's crucial to have a stable internet connection to ensure the smooth functioning of VoIP systems and avoid call dropouts or quality issues. Jitter, or the variation in latency on an internet connection, plays a much larger factor in the quality of a VoIP phone call compared to bandwidth, as long as your connection meets the modest bandwidth requirement.

Bandwidth per Codec:

  • G711 Codec: 90 kbps symmetric/call
  • G729 Codec: 35 kbps symmetric/call

Video Meetings Upstream:

  • Up to 3Mbps for video
  • 40kbps for audio

Video Meetings Downstream:

  • 2.5 Mbps for "On Stage" video in high quality
  • At least 500kbps for one incoming stream at the lowest quality
  • 200kbps per thumbnail stream (excluding on-stage)
  • 40kbps for audio

Downstream max bandwidth in a conference of n people would be 2.5Mbps + (n-2)*200kbps + 40kbps

Please make sure you have 50% of your available bandwidth free to accommodate any spike in usage. Always assume that at least 25% of your users are on a call at any time. However, depending on your company's use case, you may have a higher percentage.

To estimate the network bandwidth required to support a VoIP phone call:

  1. Choose the CODECs you plan to deploy in your network.
  2. Multiply each CODEC's bandwidth requirements by the number of simultaneous calls the network must support. For example, if you are using a G.711a/μ CODEC, and you need to support 100 simultaneous calls, then multiply 90 Kbits per second by 100 calls to calculate that you need 8.79 Mbps of symmetrical transmit-and-receive bandwidth to support the estimated call volume.
  3. Add the bandwidth required to support VoIP traffic to the bandwidth required to support your existing network traffic.

When calculating total network load, be sure to include all applications that use the network, especially applications with high bandwidth requirements (such as video conferencing). Transferring large files can play havoc on VoIP phone quality, because this type of traffic typically attempts to use as much bandwidth as possible. If the file transfer attempts to use more bandwidth than is available on the connection, you may experience large amounts of jitter.  

If you do not have a large amount of bandwidth on your connection, it is possible to partition the bandwidth you do have to ensure there is always bandwidth available for phone calls, and minimize jitter that occurs when you hit your bandwidth limit. This is called Quality of Service (QoS) and is set up on your internet router or firewall.

For more information, please contact support: https://topsoffice.ca/contact