What Broadband Speed Do You Need for VoIP?

Broadband Requirements for Business VoIP

A reliable internet connection is the foundation of any VoIP phone system. Unlike traditional landlines that run on dedicated copper circuits, a cloud phone system shares your broadband connection with other business traffic. Understanding the bandwidth, latency and quality requirements ensures your calls are crystal clear from day one.

How Much Bandwidth Does VoIP Use?

Each concurrent VoIP call typically uses 80–100 kbps of bandwidth in each direction (upload and download) when using the G.711 codec, which delivers the best audio quality. Using compressed codecs like G.729 reduces this to around 30–40 kbps per call, though with a slight reduction in audio quality.

Here is a quick guide to the bandwidth needed for simultaneous calls:

• 5 simultaneous calls — approximately 0.5 Mbps upload and download
• 10 simultaneous calls — approximately 1 Mbps upload and download
• 20 simultaneous calls — approximately 2 Mbps upload and download
• 50 simultaneous calls — approximately 5 Mbps upload and download

These figures are for voice traffic alone. You need to add bandwidth for your other business activities — email, web browsing, cloud applications and file transfers.

Latency, Jitter and Packet Loss

Raw speed is only part of the picture. Three other factors are critical for VoIP broadband quality:

Latency

Latency is the time it takes for data to travel from your phone to the VoIP platform and back. For good call quality, you need latency below 150 milliseconds. Above this threshold, callers start to notice delays and may talk over each other. Most UK fibre connections deliver latency well under 50ms.

Jitter

Jitter measures the variation in latency between packets. If some packets arrive quickly and others are delayed, the audio can sound choppy or robotic. Aim for jitter below 30 milliseconds. A jitter buffer in your VoIP system helps smooth out minor variations.

Packet Loss

When data packets are lost in transit, you hear gaps or distortion in the audio. Packet loss should be below 1% for acceptable call quality, and ideally below 0.5% for HD voice. Packet loss is often caused by network congestion or poor-quality connections.

Quality of Service (QoS) Settings

Quality of Service is a router feature that prioritises VoIP traffic over other data on your network. By tagging voice packets as high priority, QoS ensures your calls remain clear even when someone is downloading large files or streaming video. Most business-grade routers support QoS configuration, and your VoIP provider can advise on the optimal settings.

Recommended Broadband by Business Size

Choosing the right broadband product depends on the number of users and your overall internet usage:

1–5 Users: FTTC (Fibre to the Cabinet)

For small offices with a handful of VoIP users, a standard FTTC connection (up to 80 Mbps download, 20 Mbps upload) is usually sufficient. Ensure you have QoS enabled and a stable connection with low latency.

5–20 Users: FTTP (Full Fibre)

Medium-sized businesses benefit from FTTP (Fibre to the Premises), which offers symmetrical or near-symmetrical speeds and significantly lower latency. With upload speeds of 50 Mbps or more, FTTP comfortably handles 20 or more simultaneous calls alongside normal business traffic.

20+ Users: Leased Line

Larger businesses or those with mission-critical telephony should consider a dedicated leased line. A leased line provides guaranteed symmetrical bandwidth, an SLA for uptime and latency, and is not shared with other users. This is the gold standard for internet phone systems in demanding environments.

Testing Your Connection

Before deploying VoIP, it is important to test your existing broadband. A standard speed test shows bandwidth, but you should also run a VoIP-specific quality test that measures latency, jitter and packet loss. Your provider can run these tests as part of the setup process to identify any issues before you go live.

4G/5G Backup for Business Continuity

Even the most reliable broadband can occasionally fail. A 4G or 5G backup connection ensures your phone system stays online if your primary broadband goes down. Many business routers support automatic failover, switching to mobile data within seconds of detecting a broadband outage. This is particularly important for businesses where missing calls means losing revenue.

Not sure if your broadband is VoIP-ready? Get in touch for a free assessment and we will test your connection and recommend the best solution for your business.