Cloud Phone System vs Office Phone System: Which Does Your Business Need?

Quick Verdict

When you are researching business phone systems, you will see two main types: a cloud-based system (where your provider manages everything remotely) and an on-site system (where you have phone hardware installed in your office). The industry calls these 'cloud phone system' and 'on-premise PBX', but you do not need to remember those terms. Here is what actually matters for a small business in Australia: cost, reliability, features, and whether you need an IT company to manage it.

What Is a Cloud Phone System?

A cloud phone system (also called cloud PBX or virtual PBX) is a phone system where the switching hardware and software runs in a provider's data centre rather than in your office. You connect SIP-compatible desk phones or softphone apps to the provider's system over your internet connection. The provider manages all call routing, maintenance, and updates. You pay a monthly fee per seat or per user.cloud phone system is the dominant choice for Australian SMBs today because it eliminates the need for specialised on-site hardware and the IT expertise to manage it. If you are choosing a VoIP phone system for your small business and do not have dedicated IT staff, cloud phone system is almost certainly the right starting point.

What Is an Office-Based Phone System?

An on-premise PBX is a phone switch that you own and operate at your premises. Modern on-premise systems use IP-PBX software (such as FreePBX, 3CX, or Asterisk) running on a dedicated server or a purpose-built appliance. External calls commonly use separately purchased SIP trunks, although some on-premise systems can use PSTN gateways or other carrier connectivity. You handle configuration, maintenance, and any hardware failures.

Cost Comparison

Real-World Costs: What Australian Businesses Are Actually Paying

Cost comparisons between hosted and on-premise PBX are often misleading because they focus on the monthly service fee without accounting for the full picture on either side. Here is a realistic comparison for a five-seat Australian business as of 2026.

cloud phone system: Expect to pay $20 to $50 per seat per month for the service, depending on the provider and call inclusions. For five seats, that is $100 to $250 per month. Hardware (SIP phones) runs $100 to $400 per handset. Five entry-level phones add roughly $500 to $650 to the upfront cost. Setup and porting fees are typically $100 to $300 total. Using the figures above, year-one cost for five seats is approximately $1,800 to $3,950. From year two, it is the ongoing monthly fee only.

On-premise PBX: Hardware purchase for a quality IP PBX unit capable of handling five seats starts at around $800 to $2,000 for the hardware. SIP phones add another $500 to $2,000 depending on model selection. Professional installation typically runs $500 to $1,500. Ongoing SIP trunking costs (the lines that connect your PBX to the public telephone network) are $15 to $40 per trunk per month, and you will need at least two or three. Over three years, on-premise often costs more than hosted once you include the installation, IT maintenance time, and eventual hardware replacement. The exception is very high call volumes where the economics can shift.

Who Should Choose a Cloud Phone System?

cloud phone system is the right choice for most Australian small businesses. Specifically, it suits:Businesses with 1 to 30 seats who do not have dedicated IT staff. Businesses with multiple locations or remote workers who need a single phone system. Businesses that want predictable monthly costs without capital expenditure. Businesses that want to be operational quickly. cloud phone system can be provisioned in days, not weeks.To put it plainly: for the tradie with 3 staff, the medical practice with a receptionist, the retail store with a few lines, cloud phone system is not just the better choice. It is the only practical one. On-premise PBX requires someone who can configure and maintain telephony hardware. That person is not included in the plan. If you do not have IT staff, hosted is your answer.

Who Should Choose an Office-Based Phone System?

On-premise PBX is worth considering for businesses that have IT staff capable of configuring and maintaining the system, need deep customisation of call flows or integrations not available in hosted platforms, have 15 or more concurrent call paths that would make hosted per-seat pricing expensive relative to SIP trunk costs, or have specific data sovereignty or compliance requirements that preclude routing calls through a third-party cloud platform.

The Third Option: Microsoft Teams Phone

If your business already uses Microsoft 365 for email and collaboration, Teams Phone is a cloud-hosted phone-system option, with PSTN connectivity available through Microsoft Calling Plans, Operator Connect, Teams Phone Mobile or Direct Routing. Teams Phone integrates calling directly into the Teams app, which means your team can make and receive calls from their laptop, mobile, or a Teams-compatible desk phone without a separate phone system.Where Teams Phone fits: Businesses that already pay for Microsoft 365 E3 or E5 licensing, want to consolidate tools (one app for chat, video, and calls), and have simple call routing needs. It works well for knowledge workers who are already in Teams all day.Where it does not: Businesses with complex call routing requirements (multi-level IVR, sophisticated ring groups, call centre functionality), businesses that want to use existing SIP desk phones, or businesses that need transparent per-user pricing. Teams Phone licensing is genuinely confusing: Microsoft currently lists Teams Phone Standard at AU$15/user/month, a pay-as-you-go calling bundle at AU$19.50/user/month, and a domestic-calling bundle at AU$32.90/user/month, paid yearly and excluding GST. Licensing depends on the existing Microsoft 365 and Teams licences, and PSTN connectivity may instead use Operator Connect or Direct Routing. The total cost often exceeds a dedicated cloud phone system.

Feature-by-Feature: What You Get With Each Option

cloud phone system and on-premise PBX can deliver the same core feature set: auto attendant, call queuing, ring groups, voicemail-to-email, call recording, hold music, direct inward dialling, and mobile app access. The difference is not in what is technically possible but in how those features are configured, updated, and maintained.

With cloud phone system, features are managed through a web portal. Adding a ring group, changing an after-hours routing rule, or provisioning a new extension typically takes minutes and does not require a technician. Providers push feature updates and security patches automatically. When a provider adds a new capability, you get it without doing anything. For a small business without IT staff, this is the primary operational advantage of cloud phone system. Nobody needs to maintain the system.

With on-premise PBX, configuration changes require either direct access to the PBX administration interface (which assumes technical competence) or a service call from the installer or an MSP. Feature updates may require firmware upgrades that must be scheduled, tested, and applied. The trade-off for this maintenance burden is control: you can tune the system deeply, integrate it with on-site infrastructure, and operate it without an internet dependency for internal calls.

Disaster Recovery and Business Continuity

This is where cloud phone system has a fundamental advantage that is easy to overlook until you need it.cloud phone system: Cloud resilience depends on the provider's architecture and the failover features configured. Some services are geo-redundant, while others do not offer PBX failover. If your office floods, burns, or loses power, your phone system keeps running in the cloud. Calls can be routed to mobile phones, home offices, or a temporary location immediately. You can be operational within minutes of a disaster.On-premise PBX: Your phone system is a physical box in your building. If a single on-premise PBX has no secondary system or carrier-level diversion, loss of access to the site can interrupt service. Resilient on-premise designs can use backup PBXs and network-based call diversion. Recovery depends on backups (if you have them), replacement hardware (procurement time), and reconfiguration (IT time). This can take days or weeks. For businesses in bushfire, flood, or storm-prone areas of Australia, this is a genuine risk that should factor into the decision.The realistic assessment: For businesses under 20 staff without dedicated IT, cloud phone system provides enterprise-grade disaster recovery that would cost tens of thousands to replicate with on-premise hardware. This alone is often the deciding factor.

NBN Considerations for Both Options

Both hosted and on-premise PBX systems route calls over your NBN connection. The quality and reliability considerations are the same: FTTP generally provides the strongest fixed-line reliability. FTTN and FTTC performance can vary with copper-line conditions; actual VoIP suitability also depends on upload capacity, latency, jitter, packet loss, the RSP and the local network. See our NBN VoIP setup guide for detailed advice on optimising your connection for voice traffic.One difference: Local QoS can be applied to hosted or on-premise VoIP traffic. It controls traffic within networks you manage; end-to-end quality also depends on the RSP, access service and wider network path.

Scaling: How Each Option Handles Growth

cloud phone system scales instantly. Need 5 more users next month? Your provider adds them to your account, ships pre-configured phones, and your monthly bill increases by 5 users. No hardware changes, no IT visit, no downtime. Cloud capacity can often be changed without on-site hardware, but minimum terms, billing models and effective dates vary. Some services are annual, and some charge the highest quantity active during a billing month.On-premise PBX scales in steps. Adding users means verifying your hardware has capacity (phone ports, processing power, SIP trunk channels), potentially purchasing expansion cards or replacement hardware, and configuring each new extension. Reducing users does not reduce cost because the hardware is already bought. A fixed-capacity PBX appliance may require expansion hardware or replacement, while software-based or virtualised PBXs can sometimes scale through licence and compute-resource upgrades.For businesses expecting growth, change, or seasonal fluctuation, the hosted model is significantly more forgiving. This is especially relevant for Australian SMBs that may be adding remote workers, opening a second location, or testing new staff before committing to permanent headcount.

Migrating From On-Premise to Hosted: What to Expect

Many businesses currently on legacy PABX hardware are looking to migrate to cloud phone system as their hardware ages or as their NBN connection makes the business case clear. Migration is straightforward for most small businesses.

Contract considerations: For customers covered by the TCP Code, the Critical Information Summary must state the maximum early-termination charge for the offer. Check your existing contract or CIS for the applicable amount; TCP Code business coverage is subject to eligibility limits. Check your existing contract terms before committing to migration. If you are on a month-to-month plan, you can switch with standard notice.

Your existing business numbers port to the new cloud phone system company the same way they would in any carrier change. Your existing phones can often be reused if they are SIP-compatible (many modern IP phones are), though older proprietary PABX handsets are not transferable and need replacement. The configuration of ring groups, auto attendant scripts, and call flow logic needs to be recreated in the cloud phone system admin portal, which is typically a one-time setup task your new provider will assist with.

The timing risk in migration is the overlap period when both systems need to be live simultaneously during number porting. A specialist business phone company will manage this for you, keeping your existing system running until the port completes. Plan for a two to three week transition window and communicate to staff what to expect on cutover day.

What Most Businesses Get Wrong

1. Choosing on-premise because it feels more "secure". Small businesses often assume keeping hardware on-site means better security or control. In practice, most on-premise PBX systems in SMBs sit in a cupboard, rarely get firmware updates, and have no redundancy. A reputable cloud phone system company runs geo-redundant data centres with professional security monitoring, which is significantly more secure than the average SMB can achieve.2. Underestimating the total cost of on-premise. The upfront hardware cost is only the beginning. Factor in ongoing SIP trunk charges, maintenance contracts, power and cooling, firmware updates, and eventual hardware replacement (typically every 7-10 years). When you add it all up, on-premise is rarely cheaper over 5 years for businesses under 20 staff.3. Not checking NBN upload speed before committing. Both hosted and on-premise PBX need adequate upload bandwidth for concurrent calls. FTTN connections in particular can have insufficient upload speed for more than a few simultaneous calls. Check our NBN VoIP compatibility guide to understand what your connection can handle.

Your Next Steps

1. Assess your IT capability. Do you have in-house IT staff or an MSP? If not, cloud phone system is almost certainly the right choice.
2. Count your concurrent call needs. How many staff are on the phone at the same time during your busiest period?
3. Check your NBN connection type. FTTP and HFC are ideal. FTTN may have upload limitations.
4. Get a real cost comparison. Ask cloud phone system companies for a per-user monthly quote including all features. For on-premise, request hardware + SIP trunk + maintenance quotes.
5. Ask about number porting. Most active local, mobile, 13/1300 and 1800 numbers can usually be ported if the new telco accepts the request. ACMA says individual local-number ports generally take 8 to 15 days and complex local ports can take up to 30 days; mobile ports usually take about three hours.
6. Request a trial. Most cloud phone system companies offer short trials. On-premise vendors typically offer demonstrations.Want an independent recommendation? Tell us about your business and we will match you to the right solution.

For most small offices, the hosted vs on-premise debate has a clear answer: hosted wins on cost, flexibility, and maintenance overhead. Our guide to the best phone system for a small office in Australia covers this in plain language, with guidance on desk phones, softphone apps, and what features a small team actually needs.

Once you have decided a cloud phone system is the right fit for your business, the next question is which provider to use. Our guide to the best cloud phone system companies in Australia covers the local provider landscape, what features to prioritise, and the pricing ranges to expect from a quality Australian-hosted service.

The terms cloud phone system, cloud PBX, and VOIP phone system are often used interchangeably in the market. For a plain-English breakdown of what cloud PBX actually is and how it works on NBN, see Cloud PBX Australia: What It Is and Who Needs It.

For businesses that already have an on-premise PBX and are evaluating the migration path, the immediate choice is often whether to add SIP trunks to the existing system or move to a fully hosted platform. Our guide to SIP trunk vs cloud phone system in Australia covers this specific decision, including the cost crossover point and which option makes sense at different business sizes.

If you are specifically evaluating whether on-premise PBX is still viable for your situation rather than cloud, our dedicated guide to whether on-premise PBX is still worth it for Australian businesses covers the 2026 case in detail, including the team sizes where on-premise wins on cost and the hidden management overhead most comparisons leave out.

The cloud dependency question is one of the most common objections to moving away from on-premise hardware. For a clear answer on what actually happens to your numbers and service if your cloud provider goes under, our guide to what happens if your VoIP provider goes bust in Australia covers the practical steps, your number porting rights, and what Australian telecommunications law requires providers to offer.

If you are not yet sure whether your business needs a phone system at all, step back first. Many businesses with one to three staff run on a basic VOIP line and do not need a full PBX. See Do I Need a Phone System or Just a VOIP Line? for the decision framework.

What is the difference between a cloud phone system and a cloud PBX?

cloud phone system and cloud PBX refer to the same thing: a phone switching system operated by a provider in a data centre, which your business accesses over the internet. The terms are used interchangeably in the Australian market.

Can I run an on-premise PBX on NBN?

Yes. An on-premise IP-PBX connects to your carrier via SIP trunks, which run over your NBN connection. A compatible router and sufficient bandwidth are required. QoS is recommended where congestion could affect voice quality, but it is not universally required and support varies by router model and firmware. The same NBN quality considerations apply: FTTP and FTTC are preferred over FTTN for reliability.

What is a SIP trunk?

A SIP trunk is a virtual phone line delivered over an internet connection. Instead of a physical telephone line, a SIP trunk is a channel through which calls are transmitted digitally. With an on-premise PBX, you purchase SIP trunks from a carrier to handle your external calls. Most Australian carriers and cloud phone system companies offer SIP trunking.

How long does it take to set up a cloud phone system for a small business?

A basic cloud phone system for a small business can be operational within 1 to 3 business days once you have your phones. Configuration of auto attendants, ring groups, and other features can be done through the provider's portal and typically takes a few hours. Number porting, if required, takes 5 to 20 business days depending on the current carrier.

Can I run a cloud phone system and an on-premise PBX simultaneously?

Yes, hybrid setups exist. Some larger businesses run an on-premise PBX for their internal switching and desk phones while connecting to a hosted provider for SIP trunks (their inbound and outbound calling lines). Others use cloud phone system for the main office and on-premise for a specialist function such as a call centre. For most small businesses, a pure hosted setup is simpler and more cost-effective. Hybrid approaches are typically considered when there is a specific technical or compliance requirement that hosted-only cannot satisfy.

What happens to my on-premise PBX phone numbers if the hardware fails?

With an on-premise PBX, hardware failure means no calls until the system is repaired or replaced. This is one of the most significant business continuity risks of on-premise infrastructure. With cloud phone system, the hardware that processes your calls is in a data centre with redundancy built in. A failure of your office internet connection is the primary availability risk for cloud phone system, and this can be mitigated with a 4G failover router and by configuring mobile number failover in your call routing.

Is an on-premise PBX more secure than a cloud phone system?

Security depends more on configuration than on architecture. On-premise PBX systems have been extensively targeted by toll fraud attacks, where attackers exploit poorly configured SIP trunks or weak extension passwords to make international calls at your expense. cloud phone system companies invest in platform-level fraud detection and automatically block unusual international calling patterns. For most small businesses, a reputable hosted provider offers better practical security than a self-managed on-premise system that may not be regularly updated or monitored.

Related reading:

• what a PBX actually is
• cloud phone system pricing
• business phone system guide