The short version
Business 5G nearly always wins on upfront cost. There is no trenching, no building lead-in and no wait for a carrier to design a build. A router, a SIM and sometimes an external antenna, and the office can be online within days.
Over a two to five year lease the picture is less clear. Once you count every cost line, including what an outage costs the business, a permanent office with a decent fixed service available is usually better served by fixed-line primary and 5G as the backup. 5G as the only connection makes most financial sense for short leases, small teams with light upload, and addresses where fixed fibre carries a large build charge.
Our recommendation: price all three options for your address over the full lease, then decide. The rest of this guide shows how.
What goes into the total cost of each option?
The monthly plan price is the number everyone compares, and it is rarely the number that decides the outcome. These are the cost lines to put side by side.
| Cost line | Business 5G | Business NBN | Enterprise Ethernet or dedicated fibre |
|---|---|---|---|
| Monthly plan | Varies by speed tier and data policy | Varies by speed tier and support level | Higher, priced by bandwidth and service level |
| Hardware | Business 5G router, often an external antenna and mount | Router or firewall; the nbn equipment is supplied | Router or firewall; carrier equipment is supplied |
| Installation | Router setup, antenna mounting and cabling | Standard connection, sometimes a technician visit | Site survey, internal fibre run, carrier install |
| Build or construction | None | Sometimes, if the premises needs an upgrade | Possible, depending on the address and zone |
| Static IP | Rarely available on 5G plans | Often available, sometimes extra | Usually included or available |
| Contract term | Often no lock-in, but supplied modems can carry a term or non-return fee | Month to month to 36 months | Commonly multi-year |
| Backup service | Needs a second, different service | 5G backup recommended | 5G backup recommended |
| Support and restoration | Mobile network support terms | Business support terms vary by provider | Written service levels, faster restoration targets |
| Outage cost | Higher exposure to signal and congestion | Exposed to fixed-line faults | Lowest exposure, still needs a backup |
Two lines in that table are worth expanding.
Build charges. Dedicated fibre used to be a hard sell for small offices because a new lead-in could cost thousands. nbn now runs Business Fibre Zones where, in its words, most businesses can get Enterprise Ethernet “with no up-front build costs” if the provider signs a three-year plan. The offer does not cover temporary sites or complex premises. If your address is in a zone, the comparison changes a lot. nbn Business Fibre Zones covers how to check.
Contract terms. A 36-month fibre contract on a lease with 18 months left is a cost if you move. Line up the term with the lease, and ask what the exit fee is before signing.
Is business 5G cheaper than getting fibre installed over a couple of years?
Here is how the comparison usually plays out over 24 months for a small office. We have deliberately not filled in dollar figures, because plan prices change often and vary by address. Fill in the quotes you receive.
| Over 24 months | 5G only | Business NBN + 5G backup | Enterprise Ethernet + 5G backup |
|---|---|---|---|
| Upfront (hardware, install, build) | Lowest | Low to moderate | Moderate; low in a Business Fibre Zone |
| Monthly plans x 24 | One service, possibly a higher tier | Two services | Two services, the fibre one costs more |
| Exit fees if you move | Usually low | Depends on term | Depends on term |
| Days lost to slow or failed service | Highest risk | Low | Lowest |
5G only looks cheapest until two things happen. The first is that a single 5G service still needs a backup if the business cannot stop, and the natural backup for a 5G primary is a fixed service, which brings back the cost you were avoiding. The second is that a team relying on video calls and cloud phones notices congestion at the busiest hour of the day, and the fix is a higher plan tier or a second service.
Where 5G only does win over two years:
- The lease is short, or the office will move within 12 to 24 months (see internet for temporary sites)
- The fixed option at the address needs an expensive build
- The team is small and mostly downloads
- Signal at the premises is strong at the busiest time of day, tested rather than assumed
What does serious business 5G cost compared with the cheap end?
At the time of writing (October 2026), the published prices look like this:
- Telstra 5G Business Internet lists three plans from $70 to $95 a month, with no lock-in contract and a 1000 GB monthly allowance. The entry plans are speed-capped and the top plan is not.
- Optus business 5G lists plans from $59 a month for the first 12 months on its entry tier up to $99 a month for its uncapped tier, with unlimited data. The modem is $0 only if you stay connected for 36 months.
- Consumer 5G plans sit in a similar range. TPG’s, for example, are $59.99 and $69.99 a month with speed caps of 50 and 100 Mbps, and are for residential customers only.
- Enterprise 5G with committed throughput, such as Telstra Dynamic 5G, is quoted rather than listed. Telstra describes a reservation fee plus charges for performance when you use it.
Check the current price at your address before you buy, because promotions change often. Between the cheap end and the serious end, the extra money buys specific things:
- A higher speed tier. Some plans cap speed. Others let the connection run as fast as the network allows.
- Business support. Who answers, and how quickly a fault is worked, differs between consumer and business plans.
- Static IP. Mobile services usually sit behind carrier-grade NAT with no public address. If you need remote access, a site-to-site VPN or camera viewing from outside, a static IP option matters.
- Better hardware. A business router that supports failover, VPN, traffic rules and remote management, plus an external antenna where indoor signal is marginal.
- Data policy. Check what happens at high usage. “Unlimited” plans can still carry fair-use terms.
A consumer 5G home plan can look like a bargain next to a business plan. Read the terms for business use, and remember that the router supplied with a consumer plan is usually not built for failover, traffic prioritisation or remote management. Business 5G internet as your main connection covers the business-versus-consumer question in more depth.
Telstra business fibre vs the NBN already there across a five-year lease
This is a common question for an office that already has an NBN connection in the building and has been offered dedicated fibre. Telstra is just the usual example; the same logic applies to any carrier.
The NBN service already in the building has almost no connection cost and short or no contract term. Its weaknesses are asymmetrical speed on many plans, best-effort performance, and support terms that vary by provider.
Dedicated fibre costs more each month and usually comes with a longer contract. In return you get symmetrical bandwidth, a written service level and faster restoration targets.
Over five years the questions that decide it are:
- Does the business upload heavily? Cloud backups, large files, video production, many concurrent calls. If yes, symmetrical fibre removes the bottleneck.
- What does an hour offline cost? If the number is large, the restoration target in a dedicated service is worth paying for.
- Is there a build charge? In a Business Fibre Zone there may be none. Elsewhere, a large build charge spread over five years can still be reasonable, and over two years usually is not.
- Will the business still be here in five years? Match the contract to the lease and any option to renew.
Whichever you choose, keep a 5G backup on a different network. Business fibre cost covers the fixed side in more detail.
Business 5G vs fibre for a 15-person office that is growing: when do you make the jump?
Fifteen people on one 5G service can work, depending on what they do. The jump to fibre is due when you see any of these:
- Calls or video meetings break up at the same time each day
- Cloud uploads queue, and someone is scheduling backups around the internet
- The speed test at 11am is a fraction of the one at 7am
- An outage last month cost more than a year of the price difference
- The headcount plan shows the office passing 20 or 25 people within the lease
Do not wait for all of them. Fibre can take weeks or months to provision, and longer where a build is needed. Order it when the trend is clear, keep working on 5G while it is built, and move the 5G service into the backup role when fibre is live. The router that runs your 5G today can usually run both. How many staff can work off one business 5G connection covers the sizing.
We chose 5G over fibre to save money. What would make that the wrong call?
These are the situations where we would tell a client to reconsider:
- The signal survey was done once, at a quiet time. Mobile capacity is shared. Test at the busiest hour, and over several days.
- The business uploads more than it downloads. 5G upload is usually a fraction of download, and it is the first thing to suffer when the cell is busy.
- There is no backup. A 5G-only office has one path to the internet. When it fails, everything stops.
- Someone needs to reach the office from outside. Without a static IP option, remote access and some VPNs need workarounds.
- The team is growing fast. A plan that suits ten people may not suit twenty.
- The lease is long and fibre is cheap at the address. If the address is in a Business Fibre Zone, the saving from 5G may be smaller than you think.
None of these means 5G was a mistake. It may mean it should become the backup rather than the main service.
Put a number on the cost of an outage
The most useful figure in any of these comparisons is the cost of one hour without internet. A rough method:
- Count the people who cannot work without the connection, and multiply by an average hourly cost of employment.
- Add revenue that stops: card payments, bookings, orders, inbound calls.
- Add the knock-on cost: overtime to catch up, missed deadlines, penalties in client contracts.
Multiply by the number of hours you would realistically lose in a year on each option. A connection that is cheaper by a modest amount each month but likely to cost a few extra hours offline a year can be the expensive choice. This is also the number that justifies a backup service.
Get the options costed for your address
The right answer depends on the exact premises: which fixed services reach it, whether it sits in a Business Fibre Zone, and what 5G signal is like where the router will go. Kookaburra Comms is carrier-independent and does not sell SIMs on commission, so we qualify every option at the address and lay out the cost lines side by side. We then design and install the router, antenna and failover. Start with business internet and send us the address, the headcount and the lease term.