Do I Need a Phone System or Just a VOIP Line? A Plain English Answer

Someone has told you that you need a phone system. Or you have been looking at options and the terminology. PBX, hosted PBX, SIP lines, VOIP, extensions. Is making something that should be simple feel complicated. This guide cuts through it. By the end you will know whether you need a full phone system, a basic VOIP line, or something in between, and roughly what each option costs for a small Australian business.

The short answer for most businesses with one to five staff: you need a hosted phone system, and it is cheaper and simpler than you think. For a sole trader or freelancer who just needs a dedicated business number: a basic VOIP line with voicemail is probably enough. The decision turns on one question, which we will get to shortly.

What a PBX Actually Is

A PBX, or private branch exchange, is the system that sits between your phone numbers and your staff. Think of it as a traffic controller. When a call comes in, the PBX decides where to send it. Which phone to ring, in what order, and what to do if nobody answers. It handles hold music, after-hours messages, call menus, and voicemail.

Twenty years ago, a PBX was a physical box in a server room, expensive to buy and requiring an IT person to maintain. Today, the same functionality is delivered as software running on a provider's servers. You do not buy it; you subscribe to it as part of a VOIP phone plan. This is called a hosted PBX, or cloud phone system.

The cost of a hosted PBX for a small business is typically $20 to $35 per user per month with unlimited local and national calls included. If you are not sure you even need a full phone system yet, see Do I Need a Landline for My Business?

A note on AU terminology: in In Australia, “hosted phone system”, “cloud PBX”, “hosted PBX” and “cloud phone system” commonly describe provider-hosted systems. “VoIP phone system” is broader and can also refer to an on-premises system or another service using VoIP. They all refer to the same basic product structure: a phone system managed by the provider in the cloud, accessed over your internet connection, with no hardware in your office beyond the physical phones or softphone apps. When you see one provider advertising a "cloud phone system" and another advertising a "hosted VoIP PBX", they are generally selling the same type of product. The meaningful differences are in feature set, pricing structure, support quality, and how well they handle Australian-specific requirements like 000 registration and number porting.

What a Basic VOIP Line Is

A basic VoIP service may provide a phone number and a SIP account or app, but device limits, concurrent-call capacity and routing features vary by provider and plan. A softphone app on your mobile, a desk phone, or a computer. There is no routing logic, no ring groups, no auto-attendant. You get a number, calls ring on one device, and you answer them.

This is sometimes called a SIP line or a direct SIP account. A SIP line (Session Initiation Protocol line) is essentially a virtual phone line delivered over the internet, the same way a traditional phone line was delivered over copper. The cost is typically $5 to $15 per month for the line, plus call charges. A SIP line or trunk may connect a single endpoint or a PBX; extensions, management features and concurrent-call capacity depend on the service and configuration.

For a sole trader with genuinely low call volume -- fewer than five incoming calls per day, no other staff answering calls, and no requirement for a professional greeting or voicemail-to-email delivery -- a basic VoIP line may be more than adequate. A single-user VoIP account from an Australian provider costs $10 to $15 per month and delivers one phone number, one voicemail inbox, and basic call forwarding. That is the right fit for a part-time consultant, a tradesperson whose primary contact is a mobile, or a business where most client communication happens by email and the phone is an occasional backup. The question is not whether a hosted phone system is better in the abstract. It is whether your specific call volume and call-handling needs justify the additional $10 to $20 per month.

The One Question That Decides It

Here is the question: will more than one person in your business ever need to take a call at the same time?

If more than one person must take calls simultaneously, you need enough concurrent call capacity and an appropriate way to route calls. A hosted phone system is one option, but an on-premises PBX with SIP trunks or separate services can also provide that capacity. Two staff taking simultaneous calls requires two lines. A hosted phone system manages this automatically, rings phones based on rules you set, and handles the second call properly if the first line is busy.

If no. You are a sole trader, you are the only person answering calls, and you just want a business number that is not your mobile. A basic VOIP line is enough. Add a voicemail service and you have everything a one-person operation needs for $10 to $20 per month.

There is a secondary trigger that pushes businesses from a basic VoIP line to a hosted phone system, even when only one person answers calls: the auto-attendant. A hosted phone system is useful for scheduled call flows and menu options, but a custom after-hours voicemail greeting is also available from some standalone voicemail and SIP services. A basic VoIP line forwards calls to voicemail when unanswered, but it cannot play a custom professional greeting before doing so. For many sole traders, the impression created by a consistent after-hours message is worth the upgrade, even without multiple staff who need to share the line.

What a Hosted Phone System Gives You That a Basic Line Does Not

Even at entry-level pricing, a hosted phone system includes features that change how your business handles calls. These features are available on many hosted business plans, but inclusions, add-on fees and minimum-user requirements vary by provider and plan.

Ring groups allow multiple phones to ring at once when a call comes in, rather than just one desk. This means two staff can potentially answer the same inbound call, and whichever picks up first handles it. For a small team taking inbound enquiries, this alone is worth the difference between a line and a system.

After-hours routing sends calls to a voicemail, a message, or a mobile number outside business hours. Without scheduled after-hours routing, behaviour depends on the service configuration; calls may continue ringing, divert elsewhere or reach a default or customised voicemail greeting. With it, they hear your business name and get a clear next step.

Voicemail to email delivers missed call recordings to your email inbox. You never check a handset voicemail again. For a small business owner who is often out of the office, this is a significant practical improvement.

An IVR, or interactive voice response system, is the automated menu callers hear when they ring your business. "press 1 for sales, press 2 for support." You do not need this if you have one or two staff. You might want it if your business has multiple departments or if you want to route calls differently at different times.

What Each Option Costs for an Australian Small Business

Basic VOIP line (sole trader or single user): approximately $10 to $20 per month for a single number with voicemail, plus per-minute or per-call charges. Suitable for a one-person operation who just needs a dedicated business number.

Hosted phone system (2 to 10 staff): approximately $20 to $35 per user per month with unlimited local and national calls, ring groups, voicemail to email, and a basic auto-attendant. A three-person team pays roughly $60 to $100 per month for a fully functional business phone system. Hardware (desk phones) is separate, typically $80 to $300 per handset as a one-off cost.

Some hosted-PBX providers bundle system access and calling into a per-user price; others charge by extension, concurrent line, call plan or add-on. You are not buying the phone system separately and then paying for lines on top. The plan price includes both the service and the system that manages it.

Do You Actually Need a Desk Phone?

No. A softphone app is a phone application that runs on your computer or mobile. It connects to your VOIP service exactly the same way a desk phone does. For businesses where staff are often mobile or work from home, softphones can replace desk phones entirely. Many AU VOIP providers offer a softphone app as part of the plan.

If your business operates from a fixed location and you want the reliability and audio quality of a dedicated handset, a desk phone is worth the hardware cost. For a mobile or home-based operation, a softphone removes the hardware expense. Our desk phone vs softphone guide covers the trade-offs in more detail.

The NBN Phone Port: What Most Small Businesses Are Currently Using

Some businesses use an analogue handset connected to a voice port on a provider-supplied modem or router; on FTTP, the service may instead use a UNI-V port on the nbn connection box. This uses an ATA (analogue telephone adapter). A device built into the modem that lets a traditional analogue handset make calls over the internet. Your ISP controls this service and it includes the phone number.

The ATA port delivers one phone line. If the service has no call waiting, diversion or voicemail handling, a second caller may receive a busy signal; behaviour varies by provider and plan. Advanced features such as voicemail-to-email, ring groups and scheduled routing depend on the ISP voice plan and should be confirmed with the provider. You cannot take two calls at once. For a business that is growing or that misses calls regularly, this is a meaningful commercial limitation, not just a feature gap. See our guide on NBN phone options for Australian businesses for a full breakdown of what each tier delivers.

Australian Considerations Before You Switch

Most legacy copper phone services in nbn fixed-line areas were progressively disconnected, but copper services may remain in Fixed Wireless and Sky Muster areas, and some business and Special Services are exceptions. If your current business phones are connected to a voice port on your provider-supplied modem or router, or a UNI-V port on an FTTP nbn connection box, you are already on a VoIP service managed by your ISP. This port typically provides a single phone line with no hunt group, no auto-attendant, and no extension routing. Concurrent-call behaviour varies by ISP, plan and equipment. Confirm whether the service supports call waiting, multiple voice services or simultaneous call paths. A standalone VoIP service can often operate over the existing NBN connection, but confirm any effect on the ISP bundle, router configuration and voice features before changing services.

Not all VoIP services support Triple Zero. Confirm that the service supports 000, how emergency calls are handled, and how the provider records and uses location information. A VoIP provider must register your service address with the national emergency call system so that 000 calls can be linked to your physical location. For services using a public number, the carriage service provider must supply the required customer and service-address information to the IPND; confirm how the provider collects and verifies it during setup. Before signing with any provider, confirm in writing that 000 emergency calling registration is included. Lack of 000 support is a significant safety limitation. Confirm the service’s emergency-calling capability and applicable regulatory status rather than assuming every VoIP offering without it is non-compliant. If your staff ever use softphone apps to take business calls from multiple locations, understand that the 000 registration address is fixed to the address you registered -- not automatically updated when a staff member works from home.

When switching from an ISP-bundled phone service to a standalone VoIP provider, your existing phone number is portable. You do not have to give up your business number. Porting time varies by service complexity and carrier. For a single number, the current code generally requires 80% of ports within 8 business days, 90% within 10 and 98% within 15; complex ports can take longer. Do not cancel your existing service before the port is complete. Do not cancel the existing service before the port completes, because only an active service can be ported. A disconnected number is normally quarantined, and recovery may be possible but is not guaranteed. For a detailed walkthrough of the porting process, see the guide to keeping your phone number when switching to VoIP.

Before switching from your current setup to a VoIP-based phone system, confirm your NBN connection supports voice calls reliably. Bandwidth requirements vary by provider and codec. For example, Telstra Business SIP specifies at least 100 Kbit/s in each direction for every concurrent call. Test the connection during normal business load and check the provider’s requirements for bidirectional bandwidth, latency, jitter, packet loss and concurrent-call capacity; upload speed alone does not establish reliability. A congested FTTC or fixed wireless connection during peak hours can cause audio stuttering. If your connection is marginal, ask your VoIP provider whether they offer a QoS (quality of service) configuration recommendation for your router model, which prioritises voice traffic over general data.

What Most Businesses Get Wrong

The most common mistake is assuming a phone system is complex or expensive. Most small businesses are surprised to find that a three-person hosted phone system costs less than their current mobile plan per person, and includes capabilities they did not know were accessible at that price point.

The second mistake is starting with the hardware. Buying a desk phone before choosing a provider creates compatibility questions that are easily avoided by going in the other direction. Choose your provider first, confirm they support your intended phone model, then buy the hardware they recommend. See our guide on setting up a new IP phone in Australia for the step-by-step process.

The third mistake is buying a full phone system when a basic line is genuinely enough. If you are a sole trader who primarily works via mobile and just wants a second number that rings to your phone, a $15 per month VOIP line with voicemail is a perfectly reasonable solution. Do not over-engineer it.

Your Next Steps

If you have decided a hosted phone system is the right choice and want a direct recommendation on the specific setup for your team size -- whether you have 1, 2-3, or 4-5 people -- see the best phone system for 1-5 users in Australia guide, which covers recommended plan types, hardware, and AU pricing by scale.

Answer the one question: will more than one person in your business ever need to take a call at the same time? If yes, get a hosted phone system plan from an AU VOIP provider. If no, a basic VOIP line is enough.

For a hosted phone system: use our phone system sizing wizard to work out how many lines and what features you need. Then get a recommendation from an AU provider who can confirm your requirements and provide a plan price.

For a basic VOIP line: contact an AU VOIP provider and ask for a single-user plan with voicemail to email. A new service may be activated quickly, but setup time varies and number porting, handset delivery or configuration can take longer.

If you have confirmed that a hosted phone system is the right call for your business, our comparison of the best phone system for small business in Australia walks through the top AU-hosted options by price, concurrent call capacity, and which ones are easiest to set up without an IT team.

Once you have decided that a phone system is right for your business, the next question is cloud-hosted versus an on-premise box. For most small businesses, the cloud option wins on cost and flexibility. The full trade-off breakdown is in our cloud phone system vs office phone system comparison.

If you decide that desk phones are worth having, hardware choice matters. Not every phone registers cleanly with every AU VOIP provider. Our guide to the best SIP desk phone in Australia covers the most reliable models for AU VOIP networks, including which ones support auto-provisioning and what to avoid.