VOIP for Multi-Site Business Australia: One Phone System, Multiple Locations

This guide covers everything Australian multi-site businesses need to know about consolidating their phone systems onto a single hosted VOIP platform. It is based on real deployment patterns across NBN-connected offices, with honest coverage of what works, what costs more than expected, and where the common mistakes happen. By the end, you will know how inter-site calling works, what your internet connection needs to support, how to structure your number strategy, and what questions to ask a VOIP provider before signing anything.

The Old Way Was Expensive. The New Way Is Not.

Five years ago, a business with three offices in Sydney, Melbourne, and Brisbane faced a specific problem. They needed three separate PBX systems (one at each site), expensive ISDN or leased-line connections between sites to handle inter-office calls, and three separate maintenance contracts. If an IT manager wanted to move a staff member between sites, they often needed to reprovision hardware at both ends.

Calls between sites were billed as external calls. If a Sydney receptionist transferred a call to the Melbourne team, that transfer went out over the PSTN and back in, costing the same as any other outbound call. At any meaningful call volume, this added up quickly.

The PSTN copper shutdown, completed across Australia in 2025, eliminated traditional landlines as an option anyway. Every business is now on some form of digital voice service, whether they chose it or not. The question is whether you are on an ISP-controlled ATA that you cannot manage, or a proper hosted VOIP system that serves your whole business from a single cloud platform.

What 'Multi-Site' Actually Means for Your Phone System

The word 'multi-site' covers a wide range of setups, and the complexity scales roughly with the number of locations. It helps to think in three bands.

Two to three sites. This is the most common scenario: a head office and one or two branches, or a professional services firm with a CBD office and a suburban location. The requirements are straightforward. You want one main number (or separate local numbers that share the same call routing logic), free calls between sites using short extension numbers, and one admin panel to manage everything. A standard hosted VOIP provider handles this with no special configuration beyond adding users at each location.

Five to fifteen sites. At this scale, you start caring more about failover behaviour (what happens if one site loses internet), time-zone-based routing (if sites span states), and consistent call queue management across locations. You also need your provider to have clear documentation for multi-site onboarding, because adding a fifth site months after initial setup should not require starting from scratch.

Twenty or more sites. At this level, you are looking at enterprise-grade hosted PBX platforms (RingCentral, Microsoft Teams with Direct Routing, 8x8) rather than SMB-focused providers. The requirements shift toward SLA guarantees, advanced call centre features, API access for CRM integration, and dedicated account management. This guide focuses primarily on the two-to-fifteen site range, which covers most Australian SMB multi-site deployments.

The Four Core Requirements for a Multi-Site Phone System

Whatever provider you evaluate, these four requirements determine whether a hosted VOIP system will actually work for a multi-site business. Get clarity on all four before signing up.

1. Inter-Site Calling (Free Internal Calls)

On a properly configured hosted VOIP system, calls between staff at different sites are treated as internal calls. They route over the internet through the cloud PBX, not out over the PSTN and back in. This means they cost nothing extra regardless of call duration or which states the sites are in.

The mechanism is simple: every user gets an extension number (typically three or four digits). Dialling that extension from any site connects you to that person regardless of their physical location. The cloud PBX handles routing automatically. A user in Sydney on extension 201 can be called by anyone in Melbourne, Brisbane, or Perth by dialling 201. No prefix, no area code, no charge.

Ask any provider you are evaluating: are inter-site calls treated as internal? What is the extension number format? Is there any limit on simultaneous inter-site calls?

2. Centralised Management

Every user, every site, every ring group, and every call routing rule should be manageable from a single admin panel. You should not need to log into a separate system for each location.

In practice, this means you can add a new staff member at your Brisbane office from your Sydney desk in under five minutes. You can change call routing for the Melbourne site without travelling there. You can pull call reports across all sites simultaneously.

This is one of the clearest advantages of hosted VOIP over on-premise PBX. With an on-premise system, a physical PBX at each site means physical access to each site for any hardware change.

3. Consistent Inbound Experience

There are two common number strategies for multi-site businesses, and both are valid depending on your situation.

Single main number. One number (often a 1300 number) that customers call regardless of which site they are dealing with. Inbound routing logic determines which site or team answers based on time, capacity, or the caller's selection in an IVR menu. This presents a unified brand and makes it easy to route calls during an outage at one site.

Per-site local numbers. Each office has its own local geographic number. Customers in Melbourne call the Melbourne number, customers in Brisbane call the Brisbane number. Each number can still route to the same underlying VOIP system and be managed from the same admin panel. Local numbers sometimes generate more customer trust in B2B contexts where buyers want to deal with someone local.

Hybrid approach. A 1300 number for the main brand plus local geographic numbers for each site. Both feed into the same VOIP system. This is common for businesses where local presence matters (real estate, trade, professional services) but brand consistency also matters.

4. Failover (What Happens When a Site Loses Internet)

VOIP depends on internet. If a site loses its NBN connection, the phones at that site go down. This is not a VOIP flaw specifically. It is a design reality that every multi-site deployment needs to account for.

Good hosted VOIP platforms handle this through call routing failover. If calls to a site's extension or number go unanswered (because the site is offline), they can automatically redirect to another site, to a mobile, or to voicemail. This is configured in the admin panel and does not require the offline site to do anything.

For sites where downtime is genuinely unacceptable (medical practices, emergency services support, financial dealing rooms), a backup 4G LTE connection at that site is the right answer. Most business-grade routers support a secondary SIM for automatic failover. This keeps the site online even if the NBN connection fails, and the VOIP service continues without interruption.

Hosted VOIP vs On-Premise PBX for Multi-Site

The PSTN copper shutdown has effectively closed the case for new on-premise PBX deployments for most Australian businesses. Without PSTN, an on-premise PBX needs SIP trunks to connect to the outside world, which means internet dependency anyway. At that point, the on-premise box adds cost and complexity without meaningful benefit for most SMBs.

Businesses that already have an on-premise PBX and are considering whether to replace it should read our hosted PBX vs on-premise comparison for a full cost-of-ownership breakdown.

How Extension Dialling Works Across Sites

In a hosted VOIP setup, every user is assigned an extension number by the administrator. Extensions are typically three or four digits (100-199 for Site A, 200-299 for Site B, and so on, though this is entirely configurable).

When a user dials an extension, the cloud PBX looks up which device or user is registered to that extension and routes the call directly to them, regardless of physical location. There is no external call leg, no PSTN involvement, and no cost. The call travels from the caller's phone to the cloud PBX over the internet, then from the cloud PBX to the recipient's phone, also over the internet.

Transfer between sites works the same way. A receptionist in Sydney receiving a call can transfer it to the accounts team in Melbourne simply by pressing the transfer button and dialling the Melbourne extension. The customer hears hold music (if configured) and then connects to Melbourne. The whole interaction is handled within the cloud PBX.

Voicemail also integrates across sites. If a Melbourne extension does not answer, the call falls to that user's voicemail on the cloud PBX, which then delivers the recording to their email address regardless of where they physically are.

Handling Different Time Zones Across Sites

Australia spans four time zones in business use: AEST (Queensland, NSW, ACT, Victoria, Tasmania), ACST (South Australia, Northern Territory), AWST (Western Australia), and AEDT/ACDT during daylight saving periods. A business with sites in Sydney and Perth operates a three-hour time difference in summer and two hours in winter.

Hosted VOIP platforms handle this through time-based call routing rules that are configured per number or per ring group. The routing logic uses the site's local time to determine whether calls go to the live team, a voicemail, an after-hours message, or an emergency redirect to another site.

A practical example: your 1300 number routes to Sydney first. Sydney's business hours end at 5:00 PM AEST. From 5:00 PM AEST, the routing shifts to Perth, which is still open until 5:00 PM AWST (8:00 PM AEST). This effectively extends your business hours by three hours without anyone working overtime. After Perth closes, calls route to a professional after-hours voicemail.

This is one of the most genuinely useful features of a centralised hosted VOIP system for multi-state businesses. Read more about call routing strategies in our after-hours call routing guide.

Internet Requirements at Each Site

Each site in a multi-site VOIP deployment needs its own internet connection. There is no shared connection option. Every phone at every site connects to the cloud PBX independently over the site's local internet connection.

Bandwidth requirements for VOIP are modest. A single G.711 call (standard quality) uses approximately 100 Kbps of bandwidth in each direction. G.729 compression halves this to around 50 Kbps. For a site where five calls might happen simultaneously, you need roughly 500 Kbps of upload and download reserved for voice.

The more important factor on NBN is not bandwidth but jitter and packet loss. Jitter is variation in packet delivery timing. VOIP audio degrades noticeably when jitter exceeds 30ms, and becomes unusable above 50ms. Packet loss above 1% causes audible dropouts.

Most standard NBN plans (NBN 25, NBN 50, NBN 100) provide more than enough bandwidth for VOIP, but older FTTN connections with poor line quality can struggle with jitter. If a site has consistent call quality issues, run a dedicated line quality test (not just a speed test) to check jitter and packet loss specifically.

Use our VOIP Bandwidth Calculator to check whether each site's connection can support your expected call volume. If a site has marginal connection quality, Quality of Service (QoS) settings on the router can prioritise VOIP traffic over other internet usage.

Number Strategy for Multi-Site Businesses

Your inbound number strategy shapes how customers experience your business. There is no universally correct answer, but the following framework helps most multi-site businesses make the right choice.

Option 1: One 1300 Number for the Whole Business

A 1300 number costs the caller a local call rate from any landline in Australia. It routes to whichever site or team you configure. Customers see one number on your website, your invoices, your email footers, and your Google Business Profile.

This works well when your business operates as a single entity regardless of where staff are physically located. Professional services, technology companies, and businesses where the caller does not need to know which office they are reaching all suit this model.

1300 numbers are regulated by the ACMA (Australian Communications and Media Authority). You apply for and register a specific 1300 number, and you pay a monthly fee to the carrier who provides it. Costs vary but typically run $10-$20 per month for the number itself, plus call termination costs depending on your plan.

Option 2: Local Geographic Numbers Per Site

A (02) number for Sydney, (03) for Melbourne, (07) for Brisbane. Each local number rings through to the appropriate team, routes according to that site's business hours, and presents as local to customers in that area.

Research consistently shows local numbers generate higher answer rates and call-back rates in certain industries, particularly trade businesses, real estate, and healthcare where customers want to feel they are dealing with someone who understands their local area.

On a hosted VOIP system, these local numbers are virtual. They are not tied to a physical phone line at that location. They can be rerouted, combined into ring groups, or used as the caller ID for outbound calls from that site, all from the central admin panel.

Option 3: Both (The Hybrid Approach)

A 1300 number for the main brand and marketing, plus local geographic numbers for each site's direct line. The 1300 goes on the website and national materials. Local numbers go on site-specific materials, local advertising, and Google Business Profiles for each location.

Both sets of numbers feed into the same VOIP system and are managed from the same admin panel. Outbound calls from each site can present the site's local number as the caller ID.

This is the most common setup for multi-site businesses that need both national brand consistency and local customer relationships. The additional cost is modest: a few dollars per month per extra number.

Approximate Costs for Multi-Site VOIP in Australia

Multi-site VOIP pricing follows the same per-user structure as single-site VOIP. There is no separate 'multi-site fee' from most hosted providers. You pay for users, and those users can be at any location.

Typical pricing from Australian hosted VOIP providers:

• Per user per month: $25-$60 depending on provider and plan tier. Basic plans (standard calls, voicemail, basic features) sit at the lower end. Plans including call recording, advanced analytics, or CRM integration sit at the higher end.
• Phone hardware: Entry-level desk phones (Yealink T31P) from around $80-$100 per handset. Mid-range with colour display and expansion keys (Yealink T54W) from $200-$250. Prices vary, check current prices at purchase.
• 1300 number: $10-$20 per month for the number, plus per-call termination fees if not included in your plan.
• Number porting: Usually free or low-cost ($20-$50 per number) when moving existing numbers to a new provider. Timelines run 5-10 business days per ACMA regulations.

For a ten-person business across three sites, a realistic monthly cost is $350-$600 for VOIP service plus any 1300 or local number costs. Hardware is a one-time cost.

For detailed VOIP cost modelling, use our VOIP Cost Calculator or read our full VOIP cost guide for Australian businesses.

What Most Multi-Site Businesses Get Wrong

These are the three mistakes that consistently create problems in multi-site phone system deployments. They are all avoidable.

Mistake 1: Separate Providers at Each Site

This is the most common multi-site mistake. The Sydney office signed up with one provider years ago. When the Melbourne office opened, someone just got another plan with the same or a different provider. Brisbane did the same.

The result: three separate phone systems that cannot talk to each other without going out over the PSTN. Internal calls cost money. There is no extension dialling between sites. Transferring calls between offices involves giving the caller a different number to ring. Each site has its own admin panel, its own billing, its own support contacts. Managing it requires logging into three different systems.

The fix is to consolidate to a single hosted provider that supports all sites under one account. Number porting moves existing numbers across. The cost and disruption of the migration is typically recovered within two to three months from eliminated inter-site call charges and reduced admin overhead.

Mistake 2: No Failover Planning

Businesses that rely entirely on one NBN connection per site without any failover planning discover the problem at the worst possible time. An NBN outage on a busy weekday takes the site's phones offline completely. If calls are routing to that site exclusively, customers get no answer.

Basic failover planning costs very little. At minimum, configure call routing failover in your VOIP admin panel so that if a site does not answer within a set time, calls divert to another site or to a mobile. More robust protection adds a 4G backup connection at sites where downtime is genuinely costly. NBN connection-dependent businesses (call centres, reception-heavy operations, medical practices) should treat this as mandatory infrastructure, not optional.

Mistake 3: Managing Sites Independently

Even with a single VOIP provider, some multi-site businesses operate each site's phone system independently. Different ring groups, different IVR menus, different holiday schedules, maintained separately by whoever manages each site. This creates inconsistent customer experience and means that when anything needs changing business-wide (new public holiday routing, rebrand, team restructure), someone has to repeat the same changes in multiple places.

The point of a centralised hosted VOIP system is centralised management. Take the time at setup to build consistent ring group structures, consistent IVR menus, and consistent after-hours routing across all sites. Manage them from one admin panel. When something needs to change, change it once.

What to Ask a VOIP Provider About Multi-Site Support

Before committing to a provider for a multi-site deployment, get clear answers to these questions:

• Is there a per-site fee? Some providers charge a location fee on top of per-user fees. Others do not. If you have five sites, this adds up.
• How many sites can I have on one account? Most SMB-focused providers handle 2-15 sites comfortably. Beyond that, ask whether the admin interface scales gracefully.
• Can I set different business hours per site? Essential for multi-state businesses. Time-zone-aware routing should be configurable per site, not just per account.
• How does call routing failover work? What triggers failover? How quickly does it activate? Can you configure the failover destination yourself?
• Can remote workers be on the same system? Staff who work from home should be able to use the same extension and the same call routing as if they were in the office. Ask whether softphone apps are included and whether they support all the same features as desk phones.
• What is the onboarding process for a multi-site deployment? Adding a second or fifth site should not require a new sales process and a new contract. Ask how sites are added to an existing account.
• What support is available if one site has problems? If the Melbourne site has call quality issues, can support remotely diagnose and fix it, or do they need someone physically on-site?

Do You Need a Static IP at Each Site?

Most hosted VOIP deployments do not require a static IP address at each site. The phones register to the cloud PBX using the provider's SIP server address. As long as the router at each site allows outbound UDP traffic on the relevant ports (typically 5060 for SIP and a range for RTP audio), registration and calls work correctly regardless of whether the site's public IP changes.

Where a static IP becomes useful is if you are running your own on-premise SIP trunk gateway or if your provider's security model uses IP whitelisting. Some enterprise-grade VOIP providers restrict connections to pre-approved IP addresses. In that case, a static IP at each site (typically an add-on from your NBN provider for $5-$20 per month) is worth it.

Ask your VOIP provider directly whether they require or recommend a static IP for multi-site deployments. The answer varies by provider.

Australian Businesses: PSTN Shutdown and Multi-Site Implications

Australia's PSTN copper network was officially switched off in 2025. This has a specific implication for multi-site businesses that were still running any component of their inter-site connectivity over traditional copper: those circuits no longer exist. If you have not already transitioned every site to NBN-based VOIP, that transition is now mandatory rather than optional.

Number porting in Australia is governed by ACMA rules and the Local Number Portability (LNP) framework. Porting timelines run 5-10 business days per number, though batched multi-number ports can sometimes be processed faster if coordinated with the gaining provider. Plan for potential overlap where old and new systems run simultaneously during the port window.

Australian Consumer Law (ACL) protections apply to telco contracts. Providers must clearly disclose minimum monthly fees, contract lengths, and early termination fees before you sign. Month-to-month arrangements are available from most reputable hosted VOIP providers and are generally the right choice for businesses that want flexibility to add or remove sites without contractual complications.

For number porting detail, read our number porting guide. For full detail on what hosted PBX looks like in practice, see our hosted PBX vs on-premise comparison.

Your Next Steps

Use this checklist before you speak to any VOIP provider:

• Count the number of staff who need phones at each site and note each site's location.
• Identify which sites are in different states and note any time-zone differences.
• List your current numbers (including any 1300 numbers) so you know what needs to be ported.
• Check each site's NBN connection type and run a line quality test to confirm jitter and packet loss are within VOIP-safe ranges.
• Decide whether you want a single 1300 number, per-site local numbers, or both.
• Decide whether any site needs a secondary 4G connection for failover.
• Get quotes from at least two hosted VOIP providers that explicitly support multi-site on a single account.
• Ask each provider the questions listed in the section above before committing.

If you want a recommendation based on your specific site count, team size, and call volume, use our sizing tool or speak to our team directly.

How many sites can I have on one hosted VOIP system?

Most SMB-focused hosted VOIP providers can handle 2-15 sites on a single account without any special configuration. Above 15-20 sites, you may need to move to an enterprise-tier platform. Ask the provider whether their admin panel and billing scale cleanly to your expected site count before committing. There is rarely a hard technical limit, but some providers' interfaces become unwieldy at higher site counts.

Do all sites need an NBN connection for VOIP to work?

Yes. Each site needs a working internet connection. NBN is the standard option for fixed broadband in Australia. For sites in areas where NBN quality is poor, a business-grade 4G or 5G connection from a mobile carrier is a viable alternative. What you cannot do is share one internet connection across multiple sites for VOIP, because the phones at each physical location need local internet access to connect to the cloud PBX.

Can remote workers be on the same phone system as our office sites?

Yes, and this is one of the most useful features of hosted VOIP. A staff member working from home uses a softphone app on their laptop or mobile, or a desk phone at their home office. They appear on the system with their assigned extension, receive calls from their ring groups, can transfer calls to any other extension, and appear in call logs identically to in-office staff. There is no technical difference from the system's perspective between a user at Site A, Site B, or working from home.

What happens to calls if one site loses its internet connection?

Phones at the affected site go offline and cannot make or receive calls until the connection is restored. Inbound calls to numbers or ring groups that include the offline site will typically time out and then follow the configured failover routing, which could be voicemail, a redirect to another site, or a redirect to a mobile number. The key is to configure that failover routing before an outage happens, not after. Check your VOIP admin panel and confirm that every ring group has a clear failover destination.

Do I need a static IP address at each site?

Usually not. Most hosted VOIP providers work correctly with dynamic IP addresses. Phones register to the cloud PBX using the provider's SIP server address, which does not change. If your IP changes (which NBN residential and some business plans do periodically), the phones re-register automatically. The exception is if your provider uses IP whitelisting for security, which some enterprise-grade platforms do. In that case, a static IP from your NBN provider (typically $5-$20 per month) makes the configuration more reliable.

Can I keep my existing phone numbers when moving to a new VOIP provider?

Yes. Number porting moves your existing geographic, 1300, or 1800 numbers to your new VOIP provider. ACMA regulations in Australia govern this process and require the losing provider to cooperate. Timelines typically run 5-10 business days per number batch. During the port, your old service remains active, so there is no gap in reachability. Your VOIP provider should manage the porting process on your behalf. See our number porting guide for full detail.

Is there a minimum contract for multi-site VOIP in Australia?

It depends on the provider. Some offer month-to-month arrangements with no lock-in, which is ideal for businesses that want flexibility to add or restructure sites without contractual complications. Others offer 12 or 24 month contracts at a lower monthly rate. For most multi-site businesses, a month-to-month arrangement is worth paying a slightly higher rate for, especially during the first year when site counts may change. Always ask for the early termination fee before signing any fixed-term contract.