Most businesses choose a phone system on features and then spend three years regretting the choice on support and billing. The feature lists of carrier hosted PBX, Microsoft Teams Phone and 3CX overlap almost completely at the 10 to 200 staff mark. What actually separates them is cost structure, who picks up the phone when calls stop working, how much of your call flow you are allowed to change yourself, and how hard it is to leave.
A hosted PBX is a phone system owned and operated by a carrier or telco in their data centre and sold to you per user per month, with the carrier controlling the platform, the numbers and the fault path. That single sentence explains most of the differences that follow.
This post assumes you already understand how VoIP actually works for an Australian business and that you can read up on Microsoft Teams Phone in detail separately. This is the choosing part.
The three options, described honestly
Carrier hosted PBX. The carrier owns everything: the platform, the trunks, the numbers, the handsets in most cases, and the support desk. You get a portal with limited configuration rights. Changes that the portal does not cover go through the carrier as a service request.
Microsoft Teams Phone. Teams Phone is a licensed add-on that turns Microsoft Teams into your phone system. Microsoft Learn is explicit that a Teams Phone licence on its own does not make calls: the user account must be licensed with Teams Phone and also equipped with a public switched telephone network solution. There are four ways to supply that: Microsoft Calling Plan, where Microsoft is your carrier; Operator Connect, where a certified Australian carrier plugs into your tenancy; Teams Phone Mobile, where a mobile SIM number becomes the Teams number; and Direct Routing, where any carrier connects through a certified session border controller that you or your provider run.
3CX. 3CX is a software PBX you or your IT provider deploy and administer, either hosted by 3CX, on-premise, or self-hosted on a cloud provider such as Azure, AWS, Google or DigitalOcean. You bring your own SIP trunk and your own numbers. Read the fuller treatment of 3CX for Australian business if that is the direction you are leaning.
Cost is a structure question, not a price question
The three models charge on different units, and that is what determines whether the bill grows with you or sits still.
Hosted PBX is per user per month, usually on a fixed term. Every new hire is a new line item. The upside is that the number is predictable and includes the platform, the support and often the handset.
Teams Phone is per user per month for the Teams Phone licence, plus whatever your PSTN option costs. Calling Plan bundles minutes from Microsoft. Operator Connect is a separate contract with the carrier. Direct Routing means you pay for trunks from a carrier and for the session border controller, physical or virtual, that sits between them and Microsoft.
3CX licenses on simultaneous calls rather than users, and 3CX publishes its pricing on that basis as an annual subscription with hosting and support as separate additions. A business with 60 staff who are rarely all on the phone at once buys a much smaller licence than a 60-seat per-user model implies. Trunks and numbers are bought separately from an Australian carrier, so there are at least two invoices.
The trade-off is real. Per-user pricing is expensive at scale but requires no thinking. Simultaneous-call pricing is cheaper for most SMBs but you have to size it, and sizing it wrong means busy signals at your peak hour.
We are not publishing prices here because they change and because they depend on your trunk provider. Ask for the total of every line item over a three year term, not the headline per-seat rate.
Who answers when it breaks
This is the question most buyers skip and most regret.
With a carrier hosted PBX, the carrier is the single point of contact and the single point of blame. That is genuinely valuable when something is wrong at the trunk level. It is much less valuable at 9am on a Monday when the fault is a misconfigured queue and you are in a ticket queue behind a national customer base.
With Teams Phone, the support path depends entirely on which PSTN model you chose. Microsoft Learn sets this out plainly: with Calling Plan, support is Microsoft; with Operator Connect and Teams Phone Mobile it is the operator plus Microsoft; with Direct Routing it is the operator, the SBC vendor and Microsoft. Three vendors in the fault path is three vendors who can each say the problem is upstream.
With 3CX, whoever deployed it owns it. If that is a competent local provider, you get someone who can log into the PBX, look at the call logs and fix a routing rule the same morning. If it is a provider who set it up once and moved on, you own a phone system nobody understands.
Ask any provider quoting you voice a direct question: when a call fails, whose console do you open, and how fast. Then ask whether they hold the consumer protection obligations that come with reselling voice, because a provider who resells you a phone service in their own name is taking on regulated responsibilities under the Telecommunications Act, not just a margin.
For our part, TechAssist complies with the TCP Code and is a member of the Telecommunications Industry Ombudsman scheme, which means that if we cannot resolve a voice complaint you have a free and independent external umpire rather than only a commercial argument with us.
Reception, queues and the front desk
If you have a receptionist, this section decides the outcome.
Teams Phone handles auto attendants and call queues through resource accounts, and it does it well enough for most businesses. What it does less well is the classic reception workflow: a busy lamp field showing who is on a call, blind and attended transfers done in one motion, and a physical handset with programmable keys that a receptionist can drive without looking. It is improving, but a Teams-native front desk is a different job to the one your receptionist has been doing for a decade.
Carrier hosted PBX and 3CX both come from the traditional PBX lineage and handle this natively, with supported desk phones and presence panels.
The honest trade-off: Teams Phone is the better answer for a business where nobody has a dedicated reception role and calls land directly on individuals. It is the weaker answer for a practice, a clinic, a wholesaler or a trades business where one person triages every inbound call.
Mobile and remote staff
All three do mobile apps and softphones. The difference is what the staff member has to open.
Teams Phone wins outright if your staff already live in Teams all day, because there is one application and one presence state. A call, a chat and a meeting are the same window.
3CX and hosted PBX both provide iOS, Android and desktop apps, which means a second application and a second presence state to keep in sync. 3CX partially closes this with Microsoft 365 and Google Workspace integration for directory and presence.
If your field staff answer on mobile and never sit at a desk, Teams Phone Mobile is worth investigating, because it makes the mobile SIM number and the Teams number the same number.
Integration with the rest of your stack
Teams Phone integrates with Microsoft 365 by definition, and with Entra ID for identity, licensing and conditional access. That is the strongest argument for it in a Microsoft-committed business.
3CX integrates with Microsoft 365 and Google Workspace for user provisioning and contacts, and has a CRM integration layer for call popping and click to dial. It also supports Teams Direct Routing integration so Teams users and 3CX extensions can call each other, though 3CX documents this as available on Enterprise and AI Edition at 16 simultaneous calls and above, and it requires an SSL certificate from a Microsoft-approved certificate authority, a dedicated FQDN and port 5062 open on your firewall. It is not a checkbox.
Carrier hosted PBX integration varies enormously by carrier and is usually the weakest of the three. Ask for the specific integration by name before you assume it exists.
Emergency calling deserves a separate look
If you go the Teams Phone route, look carefully at how Triple Zero calls carry your location. Microsoft Learn’s comparison table shows registered address for emergency calling as included and Teams admin managed with Calling Plan, optional and operator managed with Operator Connect and Teams Phone Mobile, and not supported with Direct Routing. Dynamic location information is supported across all four but requires additional configuration on Direct Routing.
For a single-site business this is a conversation. For a business with staff spread across sites or working from home, it is a safety issue and it belongs in the decision, not in the go-live checklist.
Number porting is the same problem in all three
Your existing numbers are portable. The ACMA has declared local numbers a portable service, and the process between carriers is governed by the Local Number Portability code, currently C540:2023, published by the Australian Telecommunications Alliance. That code sets minimum standard hours of operation, activation targets and timeframes.
What differs is who drives it. A hosted PBX carrier will normally run the port for you as part of onboarding. With Teams Phone on Operator Connect, the operator does. With Direct Routing or 3CX, your trunk provider or your IT provider does.
Two rules regardless of platform. Do not cancel the old service until the port completes, because a disconnected number is far harder to recover than a ported one. And check whether every number you think you own is actually on the account you think it is on, before you sign anything.
Lock-in is the cost you pay later
Rank the three by how expensive it is to change your mind.
Carrier hosted PBX is the highest lock-in. The platform, the trunks and often the handsets are all the carrier’s, usually on a fixed term, and leaving means a full replacement plus a port.
Teams Phone lock-in depends on the PSTN model. Calling Plan ties numbers to Microsoft. Operator Connect ties them to that operator. Direct Routing is the least locked in of the Teams options because you can change carrier without touching Teams.
3CX is the lowest lock-in on paper: your trunk, your numbers, your choice of hosting, annual rather than multi-year licensing. In practice the lock-in moves to the provider who configured it, which is why documentation matters more here than anywhere else.
If you are X, choose Y
If your business runs on Microsoft 365, calls land on individuals rather than a switchboard, and staff are mobile: choose Teams Phone. Trade-off: reception and queue handling is functional rather than excellent, you take on a licence per user, and you need to make a deliberate decision about emergency calling.
If you have a receptionist or a front desk that triages every call, or you run queues that matter to revenue: choose 3CX. Trade-off: someone has to own and administer it, so it is only the right answer if you have an IT provider who will actually log in and maintain it, and you need to size simultaneous calls correctly.
If you have no internal IT, no IT provider, and you want one invoice and one number to ring: choose a carrier hosted PBX. Trade-off: you will pay more per seat, you will wait in a national support queue, and changing your mind in two years is expensive.
If you are running Microsoft 365 but need real queue and reception behaviour: run 3CX and connect it to Teams via Direct Routing. Trade-off: this is the most capable option and the most complex, and 3CX gates it behind Enterprise or AI Edition at 16 simultaneous calls and above.
One thing that applies to all four answers: the phone system is only as good as the internet service underneath it. If your connection has no committed performance class and no failover, no phone system will fix a bad call. If you are also planning a fit-out, order the carrier service before anything else, because it has the longest lead time of anything in the project.
Book a 30 minute call with TechAssist and we will map your current call flow, count your genuine simultaneous call peak and tell you which of these three fits, including when the answer is to leave your existing system alone. Call 1300 028 324 or use the form at https://techassist.au/contact/. Bring your last two phone bills and a list of your numbers.
3CX is a software-based business phone system that you licence per system rather than per user, run on your own server or have hosted for you, and connect to the public phone network through a SIP trunk you choose yourself. That last part is the whole argument. Most business phone systems sold in Australia bundle the phone system and the phone calls into one per-user monthly fee from one supplier. 3CX separates them.
Whether that separation is worth having depends on how many users you have, how much call flow complexity you need, and whether anyone in your business wants to own a decision instead of accepting a bundle.
How the licensing model actually works
This is the part people get wrong, so take it slowly.
3CX is licensed per system, per year, based on simultaneous calls. A simultaneous call is one call happening at one moment, and 3CX counts internal calls as well as external ones. It is not a per-user, per-month subscription. Adding a staff member does not add a line item. Adding enough staff that more people are on the phone at once does.
There are four editions: 3CX SMB Free, 3CX Basic, 3CX PRO and 3CX AI. SMB Free is free for up to 10 users and includes hosting, and you can create up to three free subscriptions on an account. The three commercial editions are priced on the number of simultaneous calls you need, and each simultaneous call tier carries a maximum number of users and extensions. Feature differences between Basic, PRO and AI are what you would expect: the higher editions add contact centre, integration and AI capability.
We are not quoting prices here, because 3CX changes them, runs promotions and prices in a foreign currency. Get a current quote. What we will say is that the shape of the model is the point: the cost curve flattens as headcount grows, which is why 3CX suits a business with a lot of extensions and modest concurrency, and suits a call centre far less well proportionally.
The annual subscription covers more than the licence key. It includes PBX updates and service packs, security updates, the 3CX fully qualified domain name service, automatic renewal of the Let’s Encrypt SSL certificate, IP phone firmware and provisioning template updates, CRM connector updates, VoIP provider template updates, the iOS and Android apps, video conferencing and live chat. If you self-host and let the subscription lapse, you stop receiving security updates on an internet-facing server. Do not do that.
3CX sells through partners rather than direct.
Self-hosted, hosted by 3CX, or on-premises
Three deployment choices, and they are genuinely different commitments.
On-premises means a server in your comms room. It made sense when the alternative was expensive bandwidth. Today it mostly makes sense for sites with poor or expensive internet where you want internal calls to keep working when the link drops, and for businesses with an existing virtualisation platform and someone competent running it. The trade-off is that your phone system now depends on your power, your UPS and your air conditioning.
Self-hosted in the cloud means you run 3CX on a virtual machine you control. 3CX supports Windows or Linux, on AWS, DigitalOcean, Azure or Google. You get full control, you can put the instance in an Australian region for latency and data residency, and you own the patching, the firewall rules and the backups. This is the option we most often recommend for businesses with real complexity, and it is the one that most needs a competent provider behind it, because an unmanaged internet-facing PBX is a target.
Hosted by 3CX means 3CX runs the instance. There is an annual hosting service charge based on your simultaneous call count, on top of the edition licence, and hosting is included at no charge for SMB Free and for the duration of a trial. It is the lowest-effort option and the right default for a small business that wants the licensing model without the server responsibility. The trade-off is less control over where the instance sits and what version it runs.
SIP trunk choice matters more than the PBX choice
3CX does not sell you phone calls. You bring your own SIP trunk, which in Australia means choosing a carriage service provider and, in practice, choosing whether your voice quality is good.
What to actually check when selecting a trunk:
- Australian network, Australian numbers. Geographic numbers in the right rate zone, and the ability to hold your existing numbering.
- Channel count versus your simultaneous call licence. These are separate limits and both bite. Ten SIP channels behind a four simultaneous call licence wastes money in one direction, and the reverse strands calls.
- Emergency calling. Calls to Triple Zero must be carried, and the address the emergency service organisation receives is the service address recorded in the Integrated Public Number Database. With softphones on laptops this becomes a genuine safety question rather than a compliance box, because the registered address is not where the person is. Decide in advance how mobile and remote workers reach emergency services, and tell your staff.
- Codec and transcoding policy. G.711 costs bandwidth and sounds fine. G.729 saves bandwidth and does not. Know which you are getting.
- Redundancy. A second trunk from a second provider, or at minimum a failover destination for inbound numbers when the PBX is unreachable.
- Whether the provider has a 3CX template. 3CX ships pre-configured templates for supported providers. Using one removes an entire category of tedious fault.
The other half of call quality is not the trunk at all. It is your network: the firewall, whether SIP ALG is switched on and quietly mangling your signalling (turn it off), whether you have QoS on the LAN, and the quality of your internet connection. We have resolved far more voice quality complaints by fixing a router than by changing carrier. How VoIP works for Australian businesses covers the underlying mechanics.
Number porting is a process, not a setting
Porting your existing numbers to a new provider is governed by industry codes registered with the ACMA: Local Number Portability C540:2023 for fixed geographic numbers, Mobile Number Portability C570:2024 for mobiles, and Inbound Number Portability C657:2024 for 13, 1300 and 1800 services.
Three practical points.
A simple port is a single number with no associated services and it moves quickly. A complex port is anything with multiple numbers, a number range, or a service attached, and it takes longer and involves a scheduled cutover. Most business ports with a number block are complex. Plan for a date, not for a moment.
Do not cancel the old service. Cancelling a service before the port completes strands the number, and recovering it ranges from painful to impossible. Cancellation happens automatically as part of the port.
Your billing account details must match exactly. Ports fail on the account name being an abbreviation, or on a trading name where the losing carrier holds a company name. Get a copy of the current bill before you lodge anything.
Apps, handsets and how people will actually use it
Users get a web client, a Windows app, and iOS and Android apps included in the subscription. In our experience the split in a 20 to 100 person business is roughly that reception and anyone customer-facing wants a physical handset, everyone else lives in the app, and a handful of people want both.
3CX auto-provisions supported IP phones and maintains firmware and provisioning templates as part of the subscription, which is the practical reason to buy handsets from the supported list rather than whatever is cheapest. An unsupported handset works until a firmware update, and then it is your problem.
Call flows and queues are where the value is
If you only need extension-to-extension calling and a voicemail box, almost any system will do and this decision does not matter.
3CX earns its place when the call flow is a real business process. Digital receptionist menus, ring groups, call queues with defined strategies and wait announcements, office hours and holiday routing, and a call flow designer for logic that goes beyond a menu. Queues in particular are where a hosted carrier PBX starts charging per agent and 3CX does not.
Reporting is the other half. If you are running a service desk, a bookings line or a sales team, call statistics that tell you abandonment rate and time to answer are worth more than the phone system itself.
CRM integration, and the Microsoft and Google question
3CX ships connectors for common CRM platforms, giving click to dial, screen pop on inbound calls with the matched contact, and call journalling back into the CRM record. It also integrates with Microsoft 365 and Google Workspace for user directory sync and calendar-based presence, which matters in a mixed Windows, Mac and Google environment where you do not want to maintain a second user directory by hand.
There is a Microsoft Teams integration, which routes calls between 3CX and Teams. It works, and it is a sensible answer when part of the business lives in Teams and part needs proper call handling. It is not the same as Teams Phone, and choosing between them is a real decision rather than a formality.
Where 3CX genuinely beats a carrier-provided hosted PBX
Four situations, and they are narrower than most 3CX resellers will tell you.
You have many extensions and modest concurrency. A warehouse, a school, a clinic with a phone in every consulting room, a hospitality venue. Per-user pricing punishes you for handsets that ring twice a day. Per-simultaneous-call pricing does not.
You want to keep your carrier separate from your phone system. If a carrier disappoints you, you change the trunk, not the phone system. If your phone system disappoints you, you keep your numbers. Bundled hosted PBX makes both changes into the same painful project.
Your call flows are genuinely complex and your current provider charges for every change. Owning the system means changes happen when you need them.
You need the system to sit inside your own environment for latency, data residency or integration reasons.
When 3CX is the wrong answer
Say this part out loud before you sign anything.
You are all-in on Microsoft and you value one bill and one support path. Teams Phone with a direct routing or calling plan arrangement is a legitimate and often better answer for a business that already lives in Teams. Comparing them properly is worth an hour: hosted PBX, Teams Phone or 3CX does exactly that.
You have fewer than ten users, simple needs, and nobody to manage anything. A carrier hosted PBX bundled with your mobiles is less to think about, and the licensing advantage of 3CX has not kicked in yet.
You are a real contact centre. 3CX has queues, reporting and contact centre features, and for a team of eight taking calls it is more than adequate. If you need workforce management, quality assurance scoring, omnichannel routing across voice, chat, email and social with unified reporting, and outbound dialler compliance, you want a dedicated contact centre platform.
Nobody will own it. Self-hosted 3CX is an internet-facing server. It needs patching, firewall management, certificate renewal, backup and monitoring. If you are not going to do that and you are not going to pay someone to do it, take the hosted option or take a carrier service.
You have a genuinely bad internet connection and no fallback. Fix that first.
Why we mention the TCP Code
TechAssist complies with the Telecommunications Consumer Protections Code and is a member of the Telecommunications Industry Ombudsman scheme, which is unusual for a managed service provider and which you can check yourself in the TIO’s public register of members. Most MSPs that sell you phones are reselling someone else’s service under a referral arrangement, which means the consumer protections attach to a supplier you have no relationship with.
The code registered with the ACMA is C628:2019, incorporating Variation No.1/2022. It is worth knowing that this is changing: on 27 March 2026 the ACMA announced it will determine an enforceable industry standard under section 125 of the Telecommunications Act 1997 to replace the industry-developed code, and stated that the existing 2019 TCP Code remains in force until the new standard commences, at which point the code ceases to be registered. The obligations are not going away. They are moving into direct regulation with stronger enforcement.
What that means for you as a buyer is covered in what the TCP Code means when your IT provider sells you phones. The short version: ask whoever is selling you a phone system whether they are the supplier of the carriage service or an introducer, and get the answer in writing.
If you want a straight comparison of 3CX against a carrier hosted PBX and Teams Phone for your actual call volumes and headcount, we will do the numbers and tell you if 3CX is the wrong fit. Call 1300 028 324 or book a phone system review at https://techassist.au/contact/.