Small Business Phone Systems in Australia: The 2026 NBN & VoIP Guide

Now, in 2026, setting up a business phone system in Australia looks very different from it did a few years ago. Traditional copper phone services have largely made way for NBN-based VoIP, giving small businesses more flexibility in how they handle calls.

But let’s admit that more choices can also make things confusing. Do you really need a full hosted PBX, or would a basic NBN line do the job? And if you already have an on-site PBX, is SIP trunking worth keeping?

The right choice comes down to your team, how you work, and how many calls you need to handle without missing customers.

So, in this blog, we are going to explain the main small business phone systems available in Australia, how NBN and VoIP fit in, what you need to get started, and which option makes the most sense for your business.

The 3 Types of Small Business Telephone Systems

Most small business phone systems in Australia fall into three main setups: basic NBN voice, hosted PBX and SIP trunking. The right one depends on how many staff you have, whether they’re deskbound or on the road, and whether you’re starting fresh or keeping existing hardware.

Standard NBN Business Line

A single digital voice line plugged into your NBN modem, usually through an ATA (analogue telephone adapter) if you’re keeping an old-style handset. It behaves like a landline always did, minus the copper.

Where it falls short: one call at a time, full stop. A second caller gets a busy tone or drops straight to voicemail. There’s no auto attendant, no call transfer between staff, nothing that a growing team would call a real office phone system.

Who it actually suits: a solo tradie, a single-desk consultant, or a tiny retail counter where one line has always been enough.

Hosted Phone System (Cloud PBX)

A hosted PBX is a cloud-based, virtual PBX phone system that runs your business calls through the internet instead of an on-site switchboard. Everything, like call routing, voicemail, and extensions, lives off-site with your provider and is managed through a web portal.

This is where most Australian small businesses land, and for good reason:

• No server cupboard, no PBX hardware to maintain or replace
• New starters get an extension added in minutes, not days
• Auto attendants, ring groups, call queues and voicemail-to-email are built in
• Staff can answer the business line from a desk phone, laptop softphone or mobile app, and the caller never knows the difference

At Quantacom, this is delivered through our hosted PABX platform, which keeps costs down precisely because there’s no on-site hardware to install, train staff on, or maintain.

SIP Trunking

SIP trunking connects an existing on-premises PBX (think 3CX, Yeastar, or an older Cisco system) to the outside phone network over your internet connection, replacing physical phone lines with virtual “channels.”

It’s priced by concurrent call capacity, not by user, so an 80-person office that only ever has 20 people on the phone at once buys 20 channels, not 80 seats. That maths only works in your favour if you’ve already sunk money into PBX hardware you’re not ready to retire.

How Much Does a Small Business Phone System Cost in Australia?

A hosted plan typically lands between $25 and $45 per user per month, but that figure is only one line in the total cost. Here’s what actually makes up the bill:

• Monthly user licence: $25–$45 per person for a hosted PBX, covering the core calling features and support.
• Handsets: desk phones range from roughly $80 for a basic model to $250+ for one with a colour screen and extra lines. Softphone and mobile apps are usually included at no extra cost.
• Setup and installation: many providers waive this for standard cloud setups; more complex sites with structured cabling or multiple locations will attract a one-off install fee.
• Internet connection: your existing business NBN plan usually covers this, though a faster tier may be worth it once you’re running several concurrent calls alongside everyday internet use.
• Calling charges: most Australian hosted plans bundle unlimited local and national calls; mobile and international calls are often billed separately or capped.
• Optional features: call recording, advanced reporting, and CRM integrations (like Zoho or Salesforce) sometimes carry an add-on fee.
• Number porting: usually free or a small one-off charge to bring your existing business number across.

A basic NBN line costs less month to month, but the one-call-at-a-time limit means the “savings” often show up as missed enquiries instead.

What Is the Best Phone System for a Small Business? By Business Size

It depends entirely on headcount and how your team works. Let’s understand it through this table:

Why Choose Quantacom for Business Phone Systems?

Quantacom’s hosted PABX is built around how Australian small teams actually operate, not a one-size-fits-all package. What’s included:

• Hosted PABX: cloud-based calling with no on-site server to maintain
• Cloud softphone app: a full-featured VoIP softphone for iPhone and Android, so staff can answer the business line from a personal device without exposing their personal number
• Mobile integration: calls follow staff between desk phone, laptop and mobile without the caller noticing a handover
• Microsoft Teams integration: SIP/VoIP and Teams calling in one device, with Outlook calendar visibility built in
• Zoho CRM integration: click-to-dial, call pop-ups and automatic call logging straight into Zoho
• Voicemail-to-email: messages arrive as an audio attachment with caller details in the subject line
• Australian-based support: a local team handling setup, porting and ongoing fault fixing

What Is VoIP and Why Has It Become the Standard?

VoIP (Voice over Internet Protocol) converts your voice into data packets and sends them over the internet instead of a dedicated copper phone line. That’s the entire shift in one sentence; everything else in this guide is a variation on that idea.

It became the default the moment the NBN rollout gave most of the country a broadband connection capable of carrying it cleanly. A few reasons Australian small businesses have made the switch:

• Cost: hosted plans typically run $25–$45 per user per month, well under old copper line rental
• Local numbers anywhere: you can hold a Sydney (02) or Melbourne (03) number even if your team works from home in three different states
• One number, many devices: calls to your business number can ring a desk phone, an app, and a mobile simultaneously
• No landline to lose: if you move office, your number and system move with you

None of this needs blazing internet speed. A single VoIP call uses around 100kbps, less than a video call. What actually matters is stability: latency and jitter, not raw download numbers.

What You Need to Set Up a Small Business VoIP Phone System

Six things need to be in place before you flip the switch, and skipping any one of them is where most rushed installs go wrong.

1. A stable NBN or business internet connection. FTTP and HFC generally handle voice traffic with the least fuss; FTTN connections are usually fine too, but worth checking under load.
2. Handsets or endpoints: desk phones, a softphone app on the laptop, or a mobile app. Most offices run a mix.
3. An Australian-hosted provider who can supply local geographic numbers and manage the voice network end to end.
4. Correct router configuration. This is the step most DIY setups miss. Quality of Service (QoS) needs to prioritise voice traffic, and SIP ALG, a router feature that causes far more problems than it fixes, needs to be switched off. Left on, it causes one-way audio, calls dropping at the 30-second mark, and registration failures.
5. Number porting is done through a Porting Authority Form. Timeframes depend on the type and complexity of the port. For local number portability, ACMA’s industry requirements set target timeframes of 8, 10 and 15 business days depending on the completion threshold involved. Keep your old service active until the port is confirmed; don’t cancel early.
6. A backup plan. 4G failover on your router, or automatic call diversion to mobiles, keeps the phones ringing if your internet drops.

What Happens to Your Phones During an Outage?

Your VoIP system stops working the moment your internet or power drops, unless you’ve planned for it. This matters more for a business phone system than a home one, because a missed call is a missed customer.

• Triple Zero (000): your provider must route emergency calls correctly and register your address with the Integrated Public Number Database (IPND). Confirm this is set up correctly before going live, not after an incident.
• Internet outage: cloud-level call diversion reroutes incoming calls to a mobile number automatically, so callers reach someone even if the office connection is down.
• Power outage: a desk phone with no battery backup goes dead the moment the power does. Mobile apps and softphones on a charged device or laptop keep working as long as mobile data or a hotspot is available.
• 4G/5G failover: a dual-WAN router with a SIM card switches your internet connection over automatically during an NBN outage, keeping calls (and everything else) running.
• Call diversion rules: set these up in advance through your provider’s portal, so after-hours or outage routing doesn’t rely on someone remembering to change a setting in the moment.

None of this is exotic. It’s a five-minute setup that most businesses only think about after the first outage costs them a customer.

Do You Still Need Physical Desk Phones?

Not for every desk, no. Modern small office phone systems are built so each role gets the endpoint that actually suits it, not a phone on every desk by default.

• Desk phones: still make sense for reception, warehouses, and anyone handling a high volume of calls, where dedicated buttons and hold/transfer beat fumbling with an app.
• Softphones: on a laptop, suit desk-bound office staff, especially with a headset and click-to-dial from a CRM.
• Mobile apps: turn a personal phone into a full business extension for tradies, field staff, and anyone who isn’t at a desk. The business number shows on outbound calls, and the personal number stays private.

Most Australian offices run a blend: a handset at reception, apps everywhere else.

Features Worth Paying For in an Office Phone System

Skip the enterprise feature lists most providers push and focus on what actually reduces missed calls and admin time day to day.

Auto attendant and call routing → greets callers with a menu (“Press 1 for Sales”), routes by time of day, and diverts to after-hours messaging outside trading hours automatically.

Voicemail-to-email → messages land in an inbox as audio and text, so nothing sits unheard on a handset nobody’s checked in a week.

Ring groups → rings several phones at once (or in sequence) so a call gets answered by whoever’s free, not just whoever happens to be at their desk.

4G backup and call diversion → keeps the business reachable during an internet outage by rerouting calls to mobiles at the network level, not the handset level.

Unified communications → voice, chat, video and presence in one app, useful once a team is hybrid or split across sites.

Choosing the Right Phone System for Your Small Business

Work through these five questions honestly before you sign anything.

1. How many staff, and how fast are you growing? A sole trader and a 15-person team need entirely different systems, and a system that only fits today’s headcount gets expensive to outgrow.
2. Are your people at desks, on the road, or both? Field staff need mobile apps more than they need desk phones.
3. What features do you actually use, versus what sounds nice in a demo? Call recording matters for some industries and is dead weight for others.
4. Is your internet connection reliable under load? Check it during a busy period, not a quiet Tuesday afternoon.
5. Do you prefer predictable per-user pricing or per-channel capacity pricing? This usually settles the hosted-vs-SIP question on its own.

For most small teams weighing up business phone systems for small business, a hosted setup wins on flexibility alone, since you’re not locked into hardware that’s obsolete in five years.

What to Check Before Signing with a Provider

A few non-negotiables, regardless of who you choose:

• Transparent per-user or per-channel pricing, with no surprise fees for porting or call recording
• 100% Australian-based support, with voice servers hosted in local data centres
• A clear uptime SLA backed by service credits, not just a marketing promise
• Confirmed Triple Zero (000) routing and correct address registration, which is a regulatory requirement, not optional
• Encrypted call data and Australian data storage

Every business internet connection you run VoIP over should meet the same bar. Our business NBN and internet plans are built with load balancing and backup in mind, and 4G failover is available if you want a genuine safety net against outages rather than crossed fingers.

Talk to Quantacom About Your Phone System

Choosing between a basic NBN line, hosted PBX, and SIP trunking is easier with someone who’s actually installed all three. 

At Quantacom, we look at how your team really works ( office-based, remote, or a mix ) before recommending anything, and our hosted PABX platform is backed by 100% Australian-based support and a straightforward month-to-month agreement. No long lock-in contracts, no hardware gathering dust in a cupboard.

If your team also relies on mobiles in the field, our business mobile plans run on the same network your office phones do, and our managed IT services team can handle the router and network side, so SIP ALG and QoS aren’t left to guesswork.

So, ready to see what fits your business?

Request a Free Consultation 

Speak to Our Team

FAQs

What is the best phone system for a small business?

For most teams of 2–50 staff, a hosted cloud PBX is the best fit. It scales instantly, needs no hardware, and works from anywhere with an internet connection.

Do I need the NBN for a VoIP phone system?

You need a stable broadband connection, and for most premises that’s the NBN. Fixed wireless or business fibre also work if NBN isn’t available.

Can I keep my existing business phone number when switching to VoIP?

Yes, through number porting via a Porting Authority Form. Timeframes depend on the port type, with ACMA target thresholds of 8, 10 or 15 business days.

What’s the difference between a hosted PBX and a traditional PBX?

A traditional PBX is hardware sitting on your premises. A hosted PBX runs the same functions in the cloud, with no server to maintain.

Can I just use my mobile as my business phone instead of a proper system?

You can, but a shared number, staff turnover, and no call routing catch up fast. A cloud system keeps the number with the business, not the person.

Why do my VoIP calls drop out or have one-way audio on the NBN?

SIP ALG is a common cause of VoIP registration and audio problems, but packet loss, jitter, congestion, firewall rules and network configuration can also cause dropouts or one-way audio.

Is a residential NBN plan enough for VoIP, or do I need a business plan?

For 1–5 staff on FTTP or HFC, a residential plan is often adequate. Business-grade plans matter most for guaranteed uptime and priority fault fixing.

Sources: nbn™ network technology and rollout information; ACCC guidance on Critical Information Summaries; ACCAN, telco rights and switching providers.