If your business is switching to VOIP (phone calls made over your internet connection, instead of the copper phone line) and you are not sure whether your NBN connection is fast enough to handle multiple calls at once, this calculator checks it for you. Enter your connection type, speed plan, and how many staff need to be on calls simultaneously. Results update instantly and nothing is sent anywhere.
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Get a Free AssessmentFTTP delivers fibre optic cable directly to your building, providing the most reliable NBN connection for VOIP. Upload speeds are symmetric or near-symmetric on higher plans, and latency is consistently low (typically 5-15ms). This is the gold standard for business VOIP in Australia.
FTTC brings fibre to a small distribution point on your street, with a short copper run to your premises. VOIP performance is excellent because the copper distance is very short (usually under 100 metres). Upload speeds are reliable and latency stays low, making FTTC a strong choice for business communications.
FTTN brings fibre to a street cabinet, then uses existing copper for the final connection to your building. Upload speeds vary significantly based on how far you are from the node. Businesses a long way from the node may see upload speeds well below advertised levels. VOIP quality can be inconsistent, particularly during peak usage. Always test your actual upload speed before deploying a VOIP system on FTTN.
HFC uses the old pay-TV cable network shared among homes in your area. Upload speeds are generally adequate for VOIP, but can drop during evening peak hours when neighbours are streaming. For businesses operating during standard hours, HFC is usually fine. If you run evening shifts, consider QoS settings on your router to prioritise voice traffic.
Fixed Wireless connects to a tower via a roof antenna. Upload speeds are limited on most plans (nbn's Fixed Wireless tiers offer wholesale upload of up to 20 Mbps on the common tiers and up to 40 Mbps on Fixed Wireless Superfast, with lower upload during peak hours), and latency is higher and more variable than fibre connections (30-60ms typical). VOIP call quality can fluctuate, especially during bad weather or if your tower is heavily loaded. Not ideal for businesses relying on many concurrent calls.
Satellite NBN introduces latency of 600ms or more due to the signal travelling to geostationary orbit and back. This makes real-time voice conversation impractical. Callers experience long pauses and talk-over. Satellite NBN is not recommended for VOIP. If satellite is your only option, consider a 4G/5G mobile broadband backup specifically for voice.
Some business areas have access to fibre networks outside the NBN, including providers like TPG FTTB, Opticomm, or LBNCo. These connections typically offer symmetric upload speeds and low latency, making them excellent for VOIP. Check with your provider for specific upload speed guarantees.
Enterprise ethernet provides a dedicated, symmetric connection with SLA-backed uptime guarantees. This is the premium option for businesses where call quality is non-negotiable. Upload and download speeds are equal, latency is minimal, and you are not sharing capacity with other users. Costs more, but removes internet quality as a variable entirely.
| Codec | Raw Bitrate | With Overhead | Per Call Total (both ways) | Notes |
|---|---|---|---|---|
| G.711 | 64 kbps | 87 kbps | 174 kbps | Default codec, best audio quality |
| G.729 | 8 kbps | 32 kbps | 64 kbps | Compressed, saves bandwidth significantly |
| Opus | 6-510 kbps | 30-50 kbps | 60-100 kbps | Adaptive, modern codec used by many platforms |
| G.722 HD | 64 kbps | 87 kbps | 174 kbps | HD audio quality, wideband |
| Video 720p | ~1,500 kbps | ~1,500 kbps | ~3,000 kbps | Varies by platform (Zoom, Teams, etc.) |
| Plan | Download | Upload (typical) | Available on |
|---|---|---|---|
| NBN 25 | 25 Mbps | 5 Mbps | All NBN technologies |
| NBN 50 | 50 Mbps | 20 Mbps | All NBN technologies |
| NBN 100 | 100 Mbps (500 Mbps on FTTP and HFC since Sept 2025) | 20 Mbps (50 Mbps on FTTP and HFC since Sept 2025) | All NBN technologies, uplift on FTTP and HFC only |
| NBN 250 (Home Superfast) | 250 Mbps (750 Mbps since Sept 2025) | 25 Mbps (50 Mbps since Sept 2025) | FTTP and HFC |
| NBN 1000 (Home Ultrafast) | 1,000 Mbps | 50 Mbps (100 Mbps since Sept 2025) | FTTP and HFC |
| NBN 2000 (Home Hyperfast) | 2,000 Mbps | 200 Mbps on FTTP, 100 Mbps on HFC | FTTP and HFC |
Speeds shown are nbn wholesale figures. Your retailer's plan speeds, and the speed you actually get in the evening, can be lower. Source: nbn Co, September 2025 speed tier changes.
If the calculator shows amber or red, here are six practical options, roughly ordered from easiest to most involved.
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Get a RecommendationA single VOIP call using the standard G.711 codec requires approximately 87 kbps of upload bandwidth and 87 kbps of download bandwidth (174 kbps total). Compressed codecs like G.729 use as little as 32 kbps each way. Video calls require significantly more, typically 1,500 kbps per direction for 720p quality. The overhead comes from IP, UDP, and RTP packet headers added to the raw codec bitrate.
Most NBN plans are fast enough for business VOIP, but upload speed is the limiting factor, not download speed. An NBN 50 plan with 20 Mbps upload has raw capacity for well over 100 concurrent G.711 calls, so voice bandwidth is rarely the limit for a small business; sharing the connection with other office traffic is what eats into that. The bigger concern is your NBN connection type. FTTP and FTTC are reliable for VOIP, while FTTN and Fixed Wireless can introduce quality issues due to variable speeds and higher latency.
Yes, but with caveats. FTTN (Fibre to the Node) relies on existing copper wiring from the street node to your premises. Upload speeds can be significantly lower than advertised, especially if your premises is far from the node. VOIP call quality may suffer during peak usage periods. Run a speed test to confirm your actual upload speed before committing to a VOIP system, and consider enabling QoS on your router to prioritise voice traffic.
For 10 simultaneous VOIP calls using the standard G.711 codec, you need approximately 0.87 Mbps of upload bandwidth dedicated to voice traffic. In a typical office sharing the connection with other devices, you should have at least 1.5-2 Mbps of total upload bandwidth to maintain call quality. An NBN 50 plan with 20 Mbps upload provides plenty of headroom for 10 calls.
VOIP uses both upload and download speed equally, as voice data flows in both directions during a call. However, upload speed is almost always the bottleneck for Australian NBN connections because most plans have asymmetric speeds, with upload speeds much lower than download. For example, an NBN 100 plan on FTTN typically offers 100 Mbps download but only 20 Mbps upload, and even the accelerated 500/50 Mbps tier rolled out on FTTP and HFC in September 2025 delivers upload at a tenth of its download speed. This is why VOIP bandwidth planning focuses on upload capacity.