VoIP bandwidth: What is the minimum for high-quality calls?
VoIP (Voice over Internet Protocol) has become a popular communication solution for businesses. Not only does it offer a cost-effective and scalable alternative to traditional phone systems, but often includes a wider range of features. However, the quality of VoIP calls is highly dependent on having sufficient bandwidth—the data capacity of the internet connection. Without adequate bandwidth, users may experience poor audio quality, delays, or dropped calls. To fully benefit from VoIP, it’s important to understand the bandwidth requirements and how they can impact the overall communication experience. In this article we explore the minimum bandwidth necessary to ensure high-quality calls when using VoIP.
Breaking down the minimum VoIP bandwidth requirements
Understanding the bandwidth requirements for VoIP is essential for maintaining optimal call quality and avoiding disruptions. When trying to determine the minimum bandwidth requirements to use VoIP technology in your business communications, keep in mind the following factors:
Data consumptions rates
Most office internet connections can easily handle VoIP calls, even with multiple employees, as VoIP needs less bandwidth than video or large file transfers. Many business data plans also provide unlimited data for remote workers, avoiding VoIP usage concerns. However, network congestion from bandwidth-heavy apps can impact VoIP call quality, leading to delays or dropped calls. To address this, businesses should monitor network usage and prioritize VoIP traffic. Alternatively, they can set up a dedicated VoIP network or use Quality of Service (QoS) settings to maintain stable communication.
Business usage
Most office internet connections can easily handle VoIP calls, even with multiple employees, as VoIP needs less bandwidth than video or large file transfers. Many business data plans also provide unlimited data for remote workers, avoiding VoIP usage concerns. However, network congestion from bandwidth-heavy apps can impact VoIP call quality, leading to delays or dropped calls. To address this, businesses should monitor network usage and prioritize VoIP traffic. Alternatively, they can set up a dedicated VoIP network or use Quality of Service (QoS) settings to maintain stable communication.
Concurrent calls
This is the maximum number of simultaneous calls your business expects to handle. A common rule of thumb for initial estimation is that about 10-30% of your employees might be on a call at the same peak time, but this can vary significantly based on business nature (e.g., a sales-heavy office will have more concurrent calls than a small retail shop).
Symmetrical speed
Because VoIP relies on both uploading your voice and downloading the other person’s voice simultaneously, using symmetrical internet connections (where upload/download speeds are equal) is essential for high-quality voice/video communication.
Codec types
Choosing the right codec is crucial to strike a balance between call quality and bandwidth consumption. VoIP systems use a specific codec to encode and transmit voice data. To determine the minimum dedicated bandwidth required for high-quality calls, a common reference point is the G.711 codec, which uses around 100 Kbps per call. This can serve as a simplified estimate for the bandwidth needed to maintain a high-quality VoIP experience.
| Codec | Type | Bitrate (kbps) | Use Case |
|---|---|---|---|
| G.711 | Wideband | 64-128 | Voice calls, PSTN interoperability |
| G.722 | Wideband | 24-48 | High-quality voice calls/video conferencing |
| G.726 | Narrowband | 16-40 | Low-bandwidth voice calls |
| G.729 | Narrowband | 8-32 | Low-bandwidth voice calls, mobile VoIP |
| Opus | Wide/Narrowband | 6-510 | Voice calls, video conferencing and music streaming |
| iLBC | Narrowband | 15.2 | Low-bandwidth voice calls, mobile VoIP |
| AMR-NB | Narrowband | 4.75-12.2 | Mobile voice calls |
| AMR-WB | Wideband | 6.6-23.85 | Mobile voice calls and high-quality audio |
Network overhead
Network overhead refers to the extra data or information that gets added to the actual voice data when making a VoIP call. This extra data is needed to manage and control the call, but it takes up bandwidth. Some examples include:
- Call setup and management protocols
- Packet headers that contain information about the call
- Compression and encoding voice data
- Quality of Service (QoS) mechanisms to prioritize voice data
All of this extra data gets added to the voice data, increasing the total amount of data needed to be sent over the internet for the call.
Estimating minimum VoIP-specific bandwidth
VoIP systems use a specific codec to encode and transmit voice data. Choosing the right codec is crucial to strike a balance between call quality and bandwidth consumption. To determine the minimum dedicated bandwidth required for good quality VoIP, a common reference point is the G.711 codec, which uses around 100 Kbps per call. This can serve as a simplified estimate for the bandwidth needed to maintain a high-quality VoIP experience.
| Num. of Concurrent Calls | Est. Minimum VoIP Bandwidth (upload/download) |
|---|---|
| 3 | 300 Kbps (0.3 Mbps) |
| 5 | 500 Kbps (0.5 Mbps) |
| 10 | 1000 Kbps (1.0 Mbps) |
| 20 | 2000 Kbps (2.0 Mbps) |
Factors impacting high-quality VoIP calls
While sufficient bandwidth is a cornerstone to high-quality and reliable VoIP calls, other factors have an equal importance, such as:
- Low latency: This is the delay for data to travel from one point to another. For VoIP, latency should ideally be below 150 milliseconds (ms) one-way. High latency causes noticeable delays and people talking over each other during calls.
- Low jitter: This refers to the variation in packet arrival times. High jitter leads to choppy, distorted audio. A jitter buffer can help, but consistent packet flow is key.
- Minimal packet loss: When data packets are lost in transit, parts of the conversation go missing. Packet loss should be kept below 1%.
- Quality of Service (QoS): Implementing QoS settings on your router is highly recommended. QoS prioritizes voice traffic over other types of internet traffic, ensuring that call quality remains stable even when the network is busy.
Recommendations
Small businesses can ensure high-quality, reliable VoIP communications and a positive calling experience by implementing the following recommendations.
- Estimate concurrent calls: Determine the peak number of simultaneous calls your business will likely need.
- Choose a quality codec: For good quality, assume G.711 and G.722 or research providers using Opus. Budget around 100 Kbps per call in both upload and download directions for VoIP traffic.
- Calculate dedicated bandwidth: Multiply the number of concurrent calls by the per-call bandwidth.
- Assess total internet needs: Consider all other internet activities. Your total internet bandwidth (especially upload speed) must comfortably exceed the sum of your VoIP needs and other data usage.
- Prioritize connection quality: Opt for a reliable internet service provider that offers stable connections with low latency and jitter. Fiber optic or dedicated business-grade cable connections are generally preferred over DSL or satellite for VoIP.
- Implement QoS: Ensure your network equipment supports and is configured for QoS to give voice traffic priority.
Looking ahead
By carefully considering all of the factors in determining the minimum bandwidth requirements, a small business can implement a VoIP system that delivers consistent high-quality phone and video calls. It’s always recommended to discuss your specific needs with your VoIP provider, who can often help assess your bandwidth requirements.
