NBN Phone Options for Business: What Are You Actually Getting?

There are three distinct tiers of business phone service available over an NBN connection in Australia -- and most small businesses are on the wrong one. This guide explains each tier clearly: what it costs, what it can do, what it cannot do, and who it is actually right for. By the end, you'll know exactly where your current setup sits and whether it's time to move up. All prices are in AUD including GST.

The Three Tiers of NBN Business Phone

Not all NBN phone services are the same. The term "NBN phone" just means the call travels over your internet connection rather than the old copper network. But what sits behind that varies enormously.

Here's the short version:

• Tier 1: ISP bundled phone. A basic phone line added to your broadband plan. One call at a time. No features. Very cheap.
• Tier 2: Standalone VOIP provider. A dedicated business phone service from a specialist provider. Multiple lines, real features, reasonable cost per seat.
• Tier 3: Full cloud PBX. A complete phone system hosted in the cloud. All the features of a traditional office phone system, delivered as a monthly subscription.

The right tier depends on how many people you have, how many calls you take, and what you need the phone system to actually do. We'll go through each one in detail.

Tier 1: ISP Bundled Phone -- A Line, Not a System

When you take out a broadband plan with an ISP -- Telstra, Optus, TPG, iiNet, or others -- they often offer a phone add-on. Sometimes it's included in the plan price. Sometimes it costs $10-$15/month extra. Either way, it's cheap and it's basic.

What you're getting is a phone line provided through the ATA (Analog Telephone Adapter) port built into your NBN modem. You plug in a standard analog handset -- the kind you'd buy at Officeworks -- and you can make and receive calls. The VOIP credentials are locked inside the modem firmware, programmed by your ISP. You don't control them.

To understand how ATA services work and why they're limited for business use, see our ATA adapter guide.

What Tier 1 Costs

The ISP bundled phone add-on typically costs $0-$15/month incl. GST added to your broadband bill. Some plans include it at no extra charge. Call costs vary: most plans include some local and national calls, with mobile and international calls charged per minute.

The apparent low cost is the main reason businesses end up here. But the "free" or near-free phone line costs you every time a second customer rings while you're on a call and hears an engaged tone.

What Tier 1 Cannot Do

Here's what an ISP bundled phone line cannot do:

• Take two calls at the same time. One call at a time, always.
• Route calls to different staff or ring multiple people simultaneously.
• Play hold music or put a caller on hold while you deal with another.
• Handle after-hours calls differently from business-hours calls.
• Send voicemail messages to your email inbox.
• Provide an auto-attendant ("press 1 for sales").
• Work as a softphone app on your mobile.
• Support a 1300 or 1800 number.

These aren't advanced features -- they're standard business phone functions. They're just not available on a Tier 1 service.

Who Tier 1 Is Fine For

The Tier 1 ISP phone is genuinely appropriate for a narrow group:

• Sole traders who primarily use their mobile for business and only need a landline number for occasional inbound calls.
• Home-based businesses with very low call volume (fewer than 5-10 calls per day).
• Businesses where the owner is always the only person taking calls and simultaneous calls are genuinely rare.

If you have staff, take more than a handful of calls per day, or can't afford to miss a second call while you're on the first, Tier 1 is not the right fit. Most businesses discover this too late.

Tier 2: Standalone VOIP Provider -- Business Phone Without a PBX

A standalone VOIP provider is a specialist phone company -- separate from your internet provider -- that supplies business phone services over your existing NBN connection. You set up an account, connect your phones (physical handsets or softphone apps) to their service, and you're making and receiving calls through a proper VOIP platform.

This is a fundamentally different product to the ISP bundled phone line. The VOIP service is fully independent of your internet provider. Your broadband stays with whoever you're with, and your phone service runs through a specialist provider who builds products specifically for businesses.

For a full explanation of how VOIP works over NBN, see our NBN VOIP setup guide and our plain-English guide to what VOIP actually is.

What Tier 2 Costs

Standalone VOIP services for small businesses typically cost $15-$30/seat/month incl. GST. A seat is one concurrent call -- one person on the phone at a time. A 3-person business that might have 2-3 people on the phone simultaneously needs 2-3 seats.

Most plans include a set of features -- multiple simultaneous calls, voicemail, call forwarding -- with optional add-ons for extras like 1300 numbers or call recording. Call costs are usually included or very low per minute.

For a full breakdown of what VOIP costs at this tier and others, see our VOIP cost guide.

What Tier 2 Adds

Moving from Tier 1 to Tier 2 gives you the core features a real business phone needs:

• Multiple simultaneous calls. Two or more lines active at once -- no more engaged tones when you're on a call.
• Direct inward dialling (DID). Each staff member can have their own direct number if needed.
• Voicemail to email. Missed calls are sent as audio files to your email inbox.
• Call forwarding and routing. Set rules for where calls go when unanswered.
• Softphone app. Staff can take calls on their mobile using the business number, not their personal mobile number.
• Number porting. Bring your existing business number across from your ISP. The process is regulated and takes 5-10 business days in Australia.

Tier 2 doesn't usually include a full IVR (automated attendant menu) or call queue management. Those come with Tier 3.

Who Tier 2 Is Right For

Tier 2 is the right fit for most small Australian businesses. Specifically:

• 2-10 person businesses where multiple staff take calls.
• Businesses that can't afford to miss concurrent calls.
• Businesses that want voicemail-to-email and mobile softphone without paying for a full PBX system.
• Businesses currently on a Tier 1 ISP phone who are starting to feel its limitations.

If you're regularly missing calls, have staff who need to take calls on mobile, or simply want to look and sound more professional, Tier 2 is the straightforward upgrade.

Tier 3: Full Cloud PBX -- A Complete Phone System Over NBN

A cloud PBX (also called a hosted phone system or hosted PBX) is the full-featured business phone system -- the kind that used to require expensive hardware installed on-site. In 2026, all of that functionality is delivered as a monthly subscription service over your internet connection.

The PBX is the brain of the phone system. It handles call routing, ring groups, call queues, IVR menus, call recording, reporting, and integration with other business software. With a cloud PBX, that brain lives in a data centre, not in a box in your server room. Your phones -- whether physical handsets or software apps -- connect to it over the internet.

See our in-depth comparison of the best VOIP phone systems for Australian small businesses for a full feature-by-feature breakdown.

What Tier 3 Costs

Cloud PBX services for Australian businesses typically cost $30-$50/seat/month incl. GST. The per-seat cost is higher than Tier 2, but what you're getting is substantially more capable.

Some providers bundle handset hardware into the plan (a monthly rental model). Others price the service and hardware separately. Factor in setup fees -- some providers charge $0-$500 for configuration depending on complexity.

For a side-by-side cost comparison across tiers, use our VOIP cost calculator. You can also check our guide to hidden VOIP costs so you're not surprised by what the monthly fee doesn't include.

What Tier 3 Gives You

A full cloud PBX includes everything in Tier 2 plus:

• IVR (auto-attendant). Multi-level call menus. "Press 1 for sales, press 2 for accounts, press 3 for support." Configurable by time of day, day of week, and caller ID.
• Call queuing. Callers wait in a queue with hold music rather than hearing engaged or going to voicemail immediately. Includes queue position announcements and estimated wait time.
• Ring groups and hunt groups. Define exactly which phones ring for which calls. Ring all of sales, or ring whoever's been idle longest.
• Call recording. Full inbound and outbound recording with storage and playback. Essential for compliance in some industries.
• Detailed reporting. Call volumes, wait times, missed calls, agent activity. Real data to manage your team's phone performance.
• CRM and business software integration. Click to dial from your CRM, automatic call logging, screen-pop with caller details.
• Multi-site support. Staff in different locations -- or working from home -- share a single phone system. A Sydney office and a Melbourne office look and behave as one system.
• 1300 and 1800 numbers. National numbers that route to your PBX.

Who Needs Tier 3

Tier 3 is the right fit when:

• You have 10 or more staff who use the phone regularly.
• Call volume is high -- 50+ calls per day -- and managing that volume matters to the business.
• You operate from multiple sites and need a unified phone system across all of them.
• Your industry has compliance requirements around call recording (financial services, healthcare, legal).
• You have dedicated reception or a customer service team that needs queue management and reporting.
• You want CRM integration so call data flows automatically into your business systems.

Tier 3 is not necessary for a 3-person business taking 15 calls a day. But for a 15-person business with a customer-facing team, it's the right infrastructure.

Your NBN Speed and Phone Call Quality

All three tiers of NBN phone service depend on your internet connection for call quality. Before committing to any tier -- but especially Tier 2 or Tier 3 where you're relying on multiple simultaneous calls -- check that your NBN connection can handle the load.

A single VOIP call typically uses 80-100 kbps of bandwidth in each direction. That's tiny by modern standards. The real constraint is usually not raw speed but stability -- jitter, packet loss, and upload capacity.

Key considerations for Australian businesses:

• Upload speed matters more than download for calls. VOIP sends voice out as well as receiving it. On FTTN (Fibre to the Node) connections, upload speeds can be lower than advertised.
• Jitter and packet loss cause choppy audio. If your NBN has latency spikes or drops packets, call quality suffers even if raw speed looks fine.
• Multiple simultaneous calls multiply the load. 5 concurrent calls use roughly 500 kbps in each direction -- well within most NBN plans, but worth confirming.

Use our VOIP bandwidth calculator to check whether your connection can handle your expected call volume. It factors in your NBN type, call quality setting, and concurrent call count to give you a traffic-light result. For more detail on compatibility between NBN and VOIP, see our NBN VOIP compatibility guide.

How to Decide Which Tier You Need

Here's a simple framework:

• Sole trader, mobile-first, very few calls: Tier 1 may be fine. If you mainly operate from your mobile and the landline is rarely used, the bundled ISP service is adequate.
• 2-10 people, regular call volume, can't miss concurrent calls: Tier 2. A standalone VOIP service gives you the essentials without paying for features you won't use.
• 10+ staff, high call volume, multi-site, compliance needs, or dedicated reception: Tier 3. The full cloud PBX is the right infrastructure at this scale.

If you're unsure, the sizing wizard will ask you 5 questions and give you a specific recommendation. There's no sales pitch -- it's a tool designed to help you work out what you actually need.

You can also read our guide on VOIP vs traditional phone if you're still weighing up whether to move away from a legacy setup.

You Don't Need to Change Your NBN Provider

This point is worth saying plainly because a lot of businesses assume switching phone systems means switching internet providers. It doesn't.

Tier 2 and Tier 3 VOIP services are completely separate from your broadband provider. They run over your existing NBN connection as a separate service. You keep Telstra, Optus, TPG, or whoever you're with for your broadband. Your new phone service runs alongside it.

If you're currently paying for a bundled phone line on top of your broadband, dropping that add-on will reduce your ISP bill. Your broadband plan itself is unchanged.

The migration process involves porting your existing business number to the new VOIP service. Porting is a regulated process under Australian law -- your current provider cannot block it. Our landline to VOIP migration guide walks through the full process.

What Most Businesses Get Wrong

Three mistakes come up again and again when businesses choose an NBN phone service:

Mistake 1: Treating the bundled ISP phone as a permanent solution because it's cheap. The $10-$15/month phone add-on looks like great value until you start counting missed calls. Every second call that hits an engaged tone while you're on the first call is a customer who called a competitor. For a business taking 15-20 calls per day, that's a meaningful number of leads at risk.

Mistake 2: Buying Tier 3 when Tier 2 is plenty. A 4-person business with straightforward inbound calls doesn't need call queue analytics and CRM integration. Oversizing the phone system adds cost without adding value. Use the sizing wizard to match the tier to the actual need.

Mistake 3: Not checking NBN compatibility before committing to a VOIP service. Most NBN connections handle VOIP without issues, but not all. FTTN connections with high jitter, congested fixed wireless connections, and NBN services where the ISP deprioritises VOIP traffic can all cause call quality problems. Check your connection before you commit -- and ask the VOIP provider about QoS (Quality of Service) settings to prioritise voice traffic on your router.

Your Next Steps

Here's a practical checklist to identify the right NBN phone tier and move forward:

1. Work out how many people in your business need to make or receive calls (your seat count).
2. Estimate your typical call volume -- calls per day, concurrent calls at peak.
3. List the features you actually need: simultaneous calls, voicemail to email, after-hours routing, IVR, mobile app, call recording.
4. Check your NBN connection type (FTTP, FTTN, Fixed Wireless, etc.) and run it through the bandwidth calculator to confirm it can handle your call volume.
5. Use the phone system sizing wizard to get a tier recommendation based on your inputs.
6. Model the cost with the VOIP cost calculator -- compare what you're paying now against each tier.
7. Get a recommendation from a specialist provider. Tell them how your business actually operates, not just the headcount.
8. Once signed up, initiate your number port. Keep your existing service running until the port is confirmed complete.

What is the difference between an ISP bundled phone and a VOIP service?

An ISP bundled phone uses the ATA (Analog Telephone Adapter) port on your NBN modem. It's a basic phone line locked into the modem firmware by your ISP. A standalone VOIP service is a separate product from a specialist provider -- it runs over your internet connection but is independent of your ISP. VOIP services offer multiple simultaneous calls, features like voicemail to email and mobile apps, and proper business phone functionality that the ISP bundled line doesn't provide.

How many simultaneous calls does my business need?

A rough guide: if you have 3 staff who regularly take calls, plan for at least 2 simultaneous lines (the third person is often on mobile or between calls). The rule of thumb is that your peak concurrent calls are usually 60-70% of your active headcount. The sizing wizard will ask about your call patterns and give you a specific recommendation for your situation.

Can I keep my existing business phone number when I change providers?

Yes. Number porting is a regulated process in Australia under ACMA rules. When you sign up with a Tier 2 or Tier 3 VOIP provider, you submit a porting request for your existing number. The process takes 5-10 business days. Your current service must remain active throughout the port -- do not cancel it until you receive confirmation that the port is complete.

Will my VOIP calls still work during a power outage?

No. This is an important limitation of all three NBN phone tiers. Your NBN modem and router need mains power to operate. If power goes out, your internet goes down and your phone goes with it. This is different from the old copper landline, which could work during a power outage. A UPS (Uninterruptible Power Supply) can keep your modem and router running for 30-60 minutes during a short outage. For longer outages, make sure you have a mobile number customers can reach you on.

Can I make emergency 000 calls on a VOIP service?

Most cloud VOIP services support 000 calling, but there are important caveats for Australian businesses. Unlike a traditional landline, the address registered to your VOIP service may not automatically update if you move. If you're calling 000, the emergency services may not have your correct location. Always register your correct site address with your VOIP provider. If staff work from home or from multiple sites, inform them of this limitation. For details, see our NBN VOIP compatibility guide.

How much bandwidth does a business VOIP service use?

A single VOIP call uses approximately 80-100 kbps in each direction. Five simultaneous calls use roughly 400-500 kbps each way. Most NBN plans have more than enough download speed to handle this, but upload speed and network stability matter more than raw download. Use the bandwidth calculator to check your specific connection type and call volume combination.

Do I need to change my NBN provider to get a Tier 2 or Tier 3 phone service?

No. Tier 2 and Tier 3 VOIP services are completely separate from your broadband provider. You keep your existing NBN provider and add a standalone VOIP service on top. The VOIP service runs over your internet connection independently. If you currently pay for a bundled phone line, dropping it will reduce your ISP bill -- but your broadband plan itself is unchanged.

What is a cloud PBX and does my business need one?

A cloud PBX (Private Branch Exchange) is a phone system where all the routing, queuing, and call management intelligence lives in a data centre rather than on-site hardware. It gives you IVR menus, call queues, ring groups, detailed reporting, and CRM integration. Most small businesses with 2-10 staff and standard call volumes don't need a full cloud PBX -- a Tier 2 standalone VOIP service covers everything they need at lower cost. Tier 3 becomes worth it at 10+ staff, high call volumes, multiple sites, or when compliance requires call recording.