VoIP vs Traditional Phone for Australian Business

Quick Verdict

The PSTN Copper Shutdown: Why This Decision Is Largely Made

This guide gives you a direct, honest comparison between VoIP and traditional phone systems for Australian businesses, including real cost breakdowns, NBN call quality realities, and the practical trade-offs that matter. Written by an independent editorial team with direct experience in business communications infrastructure, not by a provider trying to sell you a plan. By the end, you will know which option fits your business and exactly what switching involves.If your business is in an NBN-served area and you are still on a traditional landline, you may already be operating on a service that is scheduled for shutdown. The practical implication is that most Australian businesses choosing between VoIP and traditional phone are not comparing equal alternatives. Traditional PSTN landline is not available in most NBN areas. The real choice is between different VoIP approaches: hosted PBX, on-premise PBX with SIP trunking, or unified communications platforms. If you are specifically on Telstra SIP or hosted inbound number services, check the Telstra VoIP Shutdown guide -- those products have hard deadlines through to September 2026.

The NBN Silent Migration

When Australia rolled out the NBN, internet providers moved millions of homes and businesses from traditional phone lines to VOIP via the phone port on their modem. This happened with no warning, no explanation, and no mention of alternatives. Most customers did not notice because the transition was designed not to be noticed. The phone still worked. The number stayed the same. The bill did not change. But the underlying technology changed completely, and customers lost control of their phone service in the process.The result is a national knowledge gap. Millions of Australian households and small businesses are now on VOIP via their ISP's ATA system, and almost none of them know what that means, what they gave up, or that they have alternatives. If you are in this situation, you are not behind. The industry designed it this way deliberately. Understanding what you have is the first step to fixing it.

Cost Comparison

Call Quality: Honest Assessment

Traditional PSTN calls have consistent, predictable quality because the circuit is dedicated to your call. VoIP call quality depends on your internet connection and network configuration. On a well-configured FTTP or FTTC NBN connection, modern VoIP with a quality codec (G.722 wideband) sounds better than legacy PSTN. The issue is that not all Australian businesses have ideal NBN connectivity.FTTN (Fibre to the Node) connections in particular can introduce variable latency and packet loss during peak hours, which directly affects call quality. Businesses on FTTN who need guaranteed call quality should either request an upgrade to a higher NBN tier, use QoS settings to prioritise voice traffic on their router, or factor call quality risk into their hosted PBX choice. Our VoIP call quality guide covers this in detail.The CVC factor: Your ISP buys bandwidth from NBN Co in chunks called CVC (Connectivity Virtual Circuit). During peak hours (typically 7-9pm), if your ISP has not purchased enough CVC capacity for the number of users on your local node, everyone on that node experiences congestion. This affects VoIP call quality even if your line speed is fast. Business-grade NBN plans typically come with higher CVC priority, which is why they can be worth the premium if your business depends on consistent call quality during business hours. Our call quality guide covers diagnosis and fixes in detail.

Features Comparison

Emergency Services (000) Considerations

The Hidden Cost of Staying on a Traditional Phone Line

Most businesses that are still running on a single traditional phone line or an ISP ATA service are not aware of what that setup is costing them in lost business. The cost is not on the phone bill. It is in the calls that never get answered.

A single line means one call at a time. When a second customer calls while your line is busy, they hear an engaged tone. In 2026, almost no one leaves a message or calls back. They call the next business on their search results. For a business that takes ten inbound enquiries a day, losing even one or two of those to an engaged tone represents a significant revenue leak. If your average customer value is $500, losing two potential customers per week adds up to hundreds of thousands of dollars annually in lost pipeline. This is not a phone technology argument. It is a business cost argument.

Beyond missed calls, a single-line traditional setup offers no after-hours message, no hold capability (so callers who reach you when you are on another call get an engaged tone, not a queue), no voicemail-to-email, and no auto attendant. Existing customers calling with a service issue feel deprioritised when they repeatedly hit an engaged tone. It damages your relationship with people who are already paying you. A hosted PBX with call queuing and after-hours routing addresses all of these gaps, and for most small Australian businesses the monthly cost is less than a single lost customer.

What Happens During a Power or Internet Outage?

Business continuity is a legitimate concern when evaluating VoIP. If your internet goes down, your VoIP phones stop working. This is a real difference from traditional PSTN lines, which carried their own electrical signal and worked independently of your internet connection. However, framing this as a reason to stay on PSTN ignores two important realities.

First, Australia's PSTN copper network has been decommissioned. If you are in an NBN-served area, your existing landline is already being delivered over the NBN, meaning it is already dependent on your internet infrastructure and your modem. A power outage that takes down your router also takes down your NBN modem-connected phone. The resilience advantage of traditional phone lines largely disappeared with the copper shutdown.

Second, well-configured VoIP systems have resilience options that PSTN never offered. Most hosted PBX platforms allow you to configure a failover mobile number, so that if your VoIP extensions do not answer within a set number of rings (or if your internet connection drops entirely), inbound calls automatically divert to a nominated mobile. For critical operations, a 4G SIM router as a backup internet path means VoIP stays live even during an NBN outage. A UPS on your network switch keeps phones powered through a brief power interruption. None of these options existed with traditional PSTN.

Our Recommendation

For most Australian businesses, the real choice is not between VoIP and traditional landline. That decision was largely made when the NBN was installed. The real choice is between your ISP's ATA service, which you probably already have, and a proper business VOIP setup with a specialist provider. The ATA service works. The specialist service works better, costs about the same, and gives you actual control over your phone system. That means call routing, after-hours messages, hold music, voicemail-to-email, and the ability to add lines as your business grows. For a full breakdown of what business phone systems are available in Australia, see our business phone system guide.If you are ready to move to VoIP and are not sure which system suits your business, see our best VoIP phone system guide or use our recommendation service below.

Making the Switch: A Realistic Timeline

For a small business of two to ten staff, switching from a traditional phone setup to a hosted PBX typically takes two to four weeks from first contact to fully operational. The timeline is driven primarily by number porting, not by the technical setup itself.

Week one: assessment and provider selection. A good specialist provider will spend time understanding how your business operates before recommending anything. What numbers do you have? How many staff need to take calls? What are your busiest call periods? Do you need call recording, a 1300 number, integration with your CRM? This conversation shapes the plan. By the end of week one you should have a confirmed configuration, pricing, and a porting timeline.

Week two: hardware and system setup. If you are ordering SIP phones, most Australian distributors deliver within two to five business days. Pre-configured phones from your provider arrive ready to plug in. Your provider configures the call flow, ring groups, voicemail, and auto attendant in their admin portal. You test the system using a temporary number before your existing numbers are ported.

Weeks two to three: porting and go-live. Number porting for Australian geographic numbers (02, 03, 07, 08) takes five to ten business days. During this period, your existing service stays active. On the cutover day, your numbers transfer to the new system. You test inbound and outbound calls and confirm everything is working before contacting your old provider to cancel. The cutover window is typically a few hours during a business day.

The practical takeaway: you can be fully operational on a modern hosted PBX within three weeks of making the decision, with no downtime to your existing service during the transition. The disruption is minimal, and the setup is managed by your provider, not by you.

Understanding porting categories: Australian number porting falls into two categories. Category A (simple) ports cover standard geographic numbers moving between carriers and typically complete in 1-5 business days. Category C (complex) ports cover 1300/1800 numbers, numbers on multiple carriers, or ISDN services, and can take 10-20 business days. Your new provider handles the paperwork. You sign a porting authority form and provide your current account number. The critical rule: do not cancel your old service until the port is confirmed complete, or you risk losing the number permanently.

Your Rights When Switching: Australian Consumer Law

The Telecommunications Consumer Protections (TCP) Code gives you specific rights when changing phone providers. Understanding these before you start protects you from common traps.Critical Information Summary (CIS): Every provider must give you a one-page summary showing total minimum cost, contract length, included call allowances, excess charges, and early termination fees. If a provider will not provide this before you sign, that is a red flag.Cooling-off period: You have the right to cancel a new service during the cooling-off period (check the specific timeframe with your provider) if the service does not perform as described. This is especially relevant for VoIP, where call quality depends on your internet connection and may not be apparent until the service is active.Contract exit rights: If your current provider has changed terms materially during your contract (price increases, feature removal, service changes), you may have the right to exit without paying early termination fees. Check your contract and the TCP Code.Complaint resolution: If you cannot resolve a dispute with either your old or new provider, the Telecommunications Industry Ombudsman (TIO) investigates complaints at no cost to you. This covers billing disputes, service quality issues, and contract disagreements.A practical note on switching: Many Australian small businesses are on month-to-month plans with their current phone or ISP service, meaning they can switch at any time with standard notice (usually 30 days). If you are on a fixed-term contract, check whether porting your number triggers early termination fees. In many cases, porting the number is separate from cancelling the service. Your new VoIP provider can advise on the best sequence to minimise costs and avoid any period where your business is unreachable.

3-Year Total Cost: VOIP vs Staying on Your Current Setup

The cost comparison between VOIP and traditional phone changes significantly when you model it over three years rather than month-to-month. The worked example below uses a 5-seat Australian small business moving from a Telstra business bundle to a hosted cloud PBX. Adjust the seat count and current plan cost for your situation.

The three-year comparison typically shows VOIP breaking even on hardware costs around 6-12 months in, with ongoing savings widening from there. The more significant financial argument is not the direct cost saving -- it is the concurrent call capacity. A 5-seat Telstra bundle with 2 lines loses roughly 15-25% of inbound calls during peak hours to engaged tones. At even $100 per lost booking, a year of missed calls can represent more than the entire annual cost of the VOIP system.

What Most Businesses Get Wrong

1. Assuming VoIP means lower quality calls. On a properly configured NBN connection with QoS enabled, VoIP call quality matches or exceeds the old copper landline. The quality problems people experience are almost always caused by router misconfiguration, SIP ALG interference, or insufficient upload bandwidth, not the technology itself.2. Not planning for the porting timeline. Number porting in Australia takes 5-10 business days for a simple port, and potentially longer for complex ports (1300 numbers, multi-carrier numbers). Businesses that do not plan for this gap often end up running two systems in parallel or, worse, being unreachable during the transition.3. Comparing ISP "phone service" to a proper VoIP system. The phone service your ISP provides via the green ATA port on your modem is technically VoIP, but it has none of the business features that make VoIP worthwhile. No hold music, no call queuing, no after-hours routing. Comparing that to a hosted PBX is like comparing a paper notebook to a project management system.

Should You Switch to VOIP Now, or Wait?

Switch now if any of these apply:

• You are on a single-line ISP ATA and you lose calls when someone is already on the phone
• You have no after-hours routing (calls ring out or go to voicemail nobody checks)
• You have more than 3 staff who need to make or receive calls
• You are paying more than $150/month for a basic phone service with no ring groups, IVR, or call management features
• Your business number is printed on signage, listed on Google Maps, or carried by existing clients -- you need to port it before the PSTN copper shutdown completes
• You are in an NBN-served area and have already been migrated to an ISP ATA service (you are already on VOIP -- you are just on the worst possible version of it)

It is reasonable to wait 6-12 months if:

• You are on a short fixed-term contract (check the exit costs first -- they may be lower than you think)
• You are moving premises within 6 months (port your number when you move, not before)
• You are evaluating a significant business phone investment (multi-site, 20+ seats) and want to run a proper procurement process rather than picking a provider quickly

Your Next Steps

1. Check your current setup. Are you on the ISP green port ATA, or do you have a standalone phone system?
2. Test your NBN connection. Run a speed test and check your upload speed and jitter. You need at least 1 Mbps upload per 5 concurrent calls.
3. Talk to a specialist VoIP provider, not your ISP. A specialist will assess your actual call patterns and recommend the right plan size.
4. Plan for number porting. Start the porting process at least 2 weeks before your target switchover date.
5. Consider a parallel run. Many providers allow you to test the new system alongside your existing setup before cutting over completely.Need help deciding? Get a free, independent recommendation based on your specific business situation.

Many businesses switching from traditional phones want to know if they can keep their existing handsets. The answer is often yes -- via an ATA (Analog Telephone Adapter). See our guide to ATA adapters for analogue phones in Australia.

Many businesses that moved to NBN are technically on a basic VOIP service without realising it -- their ISP enabled a phone port on the modem or provided an ATA adapter. Our guide to ISP phone services for business explains why this basic setup falls short of what a growing business needs and what a proper phone system looks like instead.

Businesses on Optus Business phone products are often paying for services that lock voice into their broadband contract -- a bundle that makes switching feel harder than it is. Our guide to Optus business phone alternatives explains how to unbundle your phone from your ISP and what to look for in a replacement service.

TPG Business phone is a good example of a "working" phone service that is not actually a business phone system -- it connects calls but lacks ring groups, IVR, call routing, and every other feature a growing business needs. For an independent comparison of what is available instead, see our guide to TPG business phone alternatives.

One of the most common questions for businesses reviewing their phone setup is whether they still need a traditional landline at all. The short answer is no -- but you probably do need a dedicated business number. Our guide to whether your business needs a landline explains the difference, what a modern cloud number costs, and how to keep your existing number if you have one.

Is VoIP cheaper than a traditional business phone line in Australia?

Yes, in almost all cases. Hosted VoIP phone systems cost between $20 and $50 per seat per month in Australia, compared to $40 to $80 per month for traditional PSTN business lines. Call rates are typically lower as well, particularly for national and mobile calls. The savings are most significant for businesses with multiple lines or high call volumes.

Will the NBN affect my traditional phone line?

Yes. When your premises receives NBN connectivity, your existing copper-based PSTN services begin a phase-out process. Telstra and other carriers notify customers of the transition timeline. In NBN-served areas, you will eventually need to migrate all voice services to an IP-based solution. Most businesses in NBN-served areas can no longer order new traditional PSTN business lines.

What if my internet goes down. Can I still receive calls on VoIP?

During an internet outage, calls to your VoIP numbers will not reach your desk phones or softphones. Most hosted PBX providers offer automatic failover: if the system cannot reach your phones, calls are diverted to a nominated mobile number or voicemail. This means your callers can still reach you, but you will need a mobile connection to answer. Some providers offer a SIM-based failover device for critical lines.

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

Yes. Under Australian ACMA (Australian Communications and Media Authority) rules, your telephone number belongs to you, not your carrier. Number portability is a legal right in Australia. You can port geographic numbers (02, 03, 07, 08 area codes) and 1300/1800 numbers to any licensed carrier. Standard geographic number ports take five to ten business days. Do not cancel your existing service until your provider confirms the port is complete.

Is VoIP reliable enough for a business that depends on phone calls?

For businesses on FTTP, HFC, or FTTC NBN connections, VoIP reliability is comparable to traditional landlines and frequently better in terms of features and recovery options. The key variables are your NBN connection type and your router configuration (particularly QoS settings). FTTN connections introduce more variability due to the copper segment, but can still deliver acceptable quality for most business voice requirements. Discuss your specific NBN connection type with your provider before committing.

What is the difference between VoIP and the phone service on my NBN modem?

The phone service on the green port of your NBN modem is a VoIP service, but one controlled entirely by your ISP. The ISP programs your SIP credentials into the modem firmware, and you typically cannot access them or move the service to different hardware. It is a locked, ISP-controlled VoIP service, not a real business phone system. A specialist VOIP provider gives you full control: your own SIP credentials, a proper hosted PBX, multiple lines, call routing, voicemail-to-email, and the ability to use any compatible SIP phone or softphone app.

Related reading:

• best VoIP phone systems
• hosted vs on-premise PBX
• PSTN copper shutdown