Technical 5 min read 9 February 2026

NBN and VoIP: What Speed Do You Need for Business Calling?

One of the most common questions from Perth businesses considering VoIP is: "Will my NBN connection handle it?" The short answer is almost certainly yes — but here is the detailed answer so you can plan with confidence.

How Much Bandwidth Does a VoIP Call Use?

A single VoIP call uses approximately 80–100 Kbps of bandwidth (upstream and downstream combined) when using the G.711 codec — the standard high-quality audio codec used by most Australian VoIP systems.

With the compressed G.729 codec, a call uses as little as 30–40 Kbps. Most modern Hosted PBX platforms default to G.711 for best audio quality and switch to G.729 automatically on lower-bandwidth connections.

How Many Simultaneous Calls Can My NBN Handle?

NBN Plan Upload Speed Simultaneous VoIP Calls
NBN 255 Mbps~40
NBN 5020 Mbps~160
NBN 10020 Mbps~160
NBN 250 / 100050+ Mbps400+

Upload speed is the limiting factor for VoIP, not download. NBN 25 easily supports a 20-person office where typically 5–8 calls happen simultaneously.

QoS — Why It Matters More Than Raw Speed

Raw bandwidth is rarely the problem. The real enemies of VoIP call quality are:

  • Latency (ping): Should be under 150ms. Most NBN connections deliver 5–30ms to Australian VoIP servers.
  • Jitter: Variation in packet arrival times. Should be under 30ms. A good router with QoS (Quality of Service) rules fixes this.
  • Packet loss: More than 1–2% causes audio dropouts. Usually a sign of NBN line or router issues, not bandwidth.

QoS recommendation: Configure your router to prioritise VoIP traffic (UDP port 5060 and RTP ports 10000–20000). Most business-grade routers (Ubiquiti, Cisco, MikroTik) support this natively.

FTTP vs FTTN vs Fixed Wireless — Which Is Best for VoIP?

  • FTTP (Fibre to the Premises): Excellent. Lowest latency, most consistent. Ideal for VoIP-heavy businesses.
  • FTTC (Fibre to the Curb): Very good. Slightly higher latency than FTTP but rarely causes issues.
  • FTTN (Fibre to the Node): Usually fine. Quality depends on copper line length. Businesses more than 800m from the node may experience higher jitter.
  • HFC (Cable NBN): Good for most businesses. Peak-hour congestion can occasionally affect quality.
  • Fixed Wireless: Can work but is the most variable. Latency spikes during bad weather. Not recommended as the primary connection for VoIP-heavy operations.
  • Sky Muster Satellite: Not recommended for VoIP due to 600ms+ latency.

Recommended Minimum for a Perth Business

For reliable business VoIP on NBN:

  • NBN 50 or higher is recommended for any business (even if call volumes are low — you want headroom)
  • A business-grade router with QoS support (not the basic modem-router provided by NBN RSPs)
  • A wired connection for desktop IP phones — Wi-Fi introduces jitter that degrades call quality
  • A separate VLAN for voice traffic if you have 10+ simultaneous calls
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Frequently Asked Questions

How much internet speed do I need for VoIP?
Each simultaneous VoIP call uses approximately 80–100 Kbps. An NBN 25 plan with 5 Mbps upload can theoretically handle 40+ simultaneous calls — far more than most small businesses need.
Will VoIP work on NBN Fixed Wireless?
Usually yes, but Fixed Wireless is more variable than FTTP or FTTN. Latency spikes during bad weather can affect call quality. For critical business communications, a wired NBN connection is preferred.
What causes poor VoIP call quality on NBN?
Poor quality is almost always caused by high latency (>150ms), jitter (>30ms), or packet loss — not raw speed. A router with QoS rules and a wired connection for phones fixes most issues.
Does VoIP affect my internet speed for other uses?
Minimally. Each call uses only 80–100 Kbps. Even 10 simultaneous calls use under 1 Mbps — invisible on any NBN 50 or higher plan.