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One of the most common worries businesses raise before switching to a cloud phone system is bandwidth. Will the internet connection handle the calls? Will voice quality suffer when the office is busy? The reassuring answer is that VoIP is surprisingly light on bandwidth — far lighter than streaming video or large downloads — and most modern Australian connections handle it with ease.

Still, getting the numbers right matters. In this guide we explain exactly how much bandwidth VoIP uses, how to calculate what your business needs, and how to make sure every call sounds crystal clear.

How much bandwidth does a single VoIP call use?

A typical VoIP call uses roughly 85 to 100 kilobits per second (Kbps) in each direction when you account for the audio codec and network overhead. That is a tiny amount of data. To put it in perspective, a single standard-definition video stream can use 30 to 40 times more bandwidth than one phone call.

Because calls use bandwidth in both directions at once, you need to plan for that capacity on both your upload and download speeds — and upload is usually the tighter constraint on Australian connections.

Calculating bandwidth for your business

The simple formula is:

Number of simultaneous calls × 100 Kbps = bandwidth required (each direction)

Here is how that scales for a typical office:

• 5 simultaneous calls ≈ 0.5 Mbps each way
• 10 simultaneous calls ≈ 1 Mbps each way
• 25 simultaneous calls ≈ 2.5 Mbps each way
• 50 simultaneous calls ≈ 5 Mbps each way

An important distinction: you size for simultaneous calls, not total staff. A 20-person office rarely has all 20 on the phone at once. A realistic estimate is that a third to a half of your team might be on a call during the busiest moments.

Why speed is only half the story

Raw download speed gets all the attention in NBN marketing, but for voice quality, three other factors matter just as much:

• Latency — the delay between speaking and being heard. Keep it under 150 milliseconds for natural conversation.
• Jitter — variation in how data packets arrive. High jitter causes choppy, robotic audio.
• Packet loss — data that never arrives, heard as words dropping out. Aim for well under 1%.

A connection can be fast and still deliver poor calls if latency, jitter or packet loss are high. This is why a stable connection beats a merely fast one for voice.

VoIP and the NBN: what Australian businesses should know

The NBN comfortably supports VoIP across all its common business plans. Even an entry-level plan provides far more capacity than a handful of simultaneous calls require. The bigger considerations are the type of connection and having a backup:

• Fibre-based connections (FTTP and FTTC) offer the most consistent performance for voice.
• Fixed wireless and satellite can work but may show higher latency and jitter, so quality of service settings matter more.
• A 4G or 5G failover keeps your phones running if the NBN drops — a major advantage of cloud phones, since calls can reroute automatically to mobiles or another site.

How to test your connection before you switch

1. Run a VoIP-specific speed test. Standard speed tests measure download speed; a VoIP test also measures jitter, latency and packet loss.
2. Test during your busy period. A connection that looks great at 7am may struggle at 11am when the whole office is online.
3. Check your upload speed. Many issues trace back to limited upload capacity rather than download.

Five ways to guarantee great call quality

• Prioritise voice traffic with Quality of Service (QoS) settings on your router so calls take priority over downloads.
• Use wired connections for desk phones where possible, rather than relying on Wi-Fi.
• Keep firmware updated on routers and handsets.
• Separate voice and data on a dedicated network or VLAN in larger offices.
• Add a failover connection so your phones survive an outage.

The bottom line

VoIP needs far less bandwidth than most businesses expect — around 100 Kbps per call. The real secret to flawless calls is not a huge connection, but a stable one with voice traffic given priority. For the vast majority of Australian businesses on the NBN, the infrastructure to run a professional cloud phone system is already in place.

Uniden Voice assesses your connection, configures QoS and sets up failover so your Voice Over Cloud system sounds great from day one. Get in touch for a free connection check.