Cloud phone system for small business: a Melbourne buyer's guide to Teams Phone, 3CX and hosted PBX
Cloud phone system for small business: compare Teams Phone, 3CX and hosted PBX, keep your numbers, and get 000 calls, NBN and security right before you switch.
A cloud phone system for small business replaces the PBX box in your comms cupboard with a switchboard that runs online, carrying calls over your internet connection to desk phones, laptops and mobiles. For most Melbourne small businesses the shortlist is Microsoft Teams Phone, 3CX or a hosted PBX, and you keep your existing numbers. Key IT plans, moves and supports all three.
What is a cloud phone system, and how is it different from a PBX?
A traditional PBX is a box on your premises that routes calls between extensions and out to the phone network. A cloud phone system does that job from a data centre or Microsoft's cloud. Calls travel as VoIP (voice over internet protocol), and staff answer on a desk handset, a softphone on their computer or an app on their mobile.
The features are familiar: Microsoft lists cloud voicemail, call forwarding, call transfer, auto attendants, call queues and caller ID among Teams Phone's PBX capabilities. What changes is that there is no PBX box on site to maintain or replace.
Teams Phone vs 3CX vs hosted PBX: which fits a small business?
All three cover the basics; here is where they differ.
| Compared | Microsoft Teams Phone | 3CX | Hosted PBX |
|---|---|---|---|
| Cost model | Per-user monthly add-on licence, plus a calling service from a telco | One flat annual licence for the whole system, sized by simultaneous calls, plus call charges | Monthly fee per seat, set by the provider |
| What you need | A Microsoft 365 plan, a Teams Phone licence per caller, and a calling service such as Operator Connect or Direct Routing | A 3CX licence, somewhere to run it (3CX-hosted, cloud or your own server) and a SIP trunk | The provider's seat plan; check which numbers and calls it covers |
| Best for | Staff who live in Microsoft 365 all day and mostly call people directly | Businesses where the phone is the front door: queues, menus, ring groups and call reports | Offices wanting familiar desk-phone features with nothing to run themselves |
| Call quality depends on | Your internet link, office Wi-Fi and keeping calls off the VPN | Your internet link, firewall configuration and the SIP trunk provider | Your internet link and the provider's network |
| Watch out for | Account security: a stolen Microsoft 365 password is also a stolen phone line | Patching and dialling restrictions, especially on a self-managed server | Contract length, and whether your call flows leave with you |
One Australian detail is easy to miss: Microsoft's own Calling Plans, where Microsoft acts as your phone company, are listed as not available to purchase in Australia. Here, Teams reaches outside numbers through Microsoft's other PSTN connectivity options, chiefly Operator Connect, where a certified telco plugs its calling service into Teams, and Direct Routing, where your chosen provider connects through a certified session border controller. Key IT compares these against your current phone bill before recommending one; our Microsoft Teams Voice page covers the setup.
3CX's published price list is in US dollars excluding tax. In October 2026 its smallest paid licence, the Basic edition with eight simultaneous calls, was listed at US$300 a year. That means eight conversations at once, not eight staff: 3CX allows up to 40 users on it.
For real estate agencies, the deciding factor is often agents and property managers who need the office number on their mobile. For professional services firms such as consultancies and advisory practices, it is usually the front desk: queues, after-hours messages and seeing which calls went unanswered.
What does your NBN connection need for clear calls?
Less bandwidth than you'd expect, but a clean line. Microsoft recommends 58 kbps up and down for each Teams audio call, or 76 kbps for best performance, so ten simultaneous calls need well under 1 Mbps. Microsoft notes that static, cut-outs and robotic-sounding voices can point to jitter or packet loss rather than a lack of bandwidth.
Protect your upload
A big cloud backup can crowd out voice; quality of service settings put calls first.
Keep calls off the VPN
Microsoft recommends a split-tunnel VPN, because VPNs typically aren't designed for real-time media.
Add a static IP and a backup link
Key IT supplies business NBN and corporate fibre with a static IP on every plan, plus 4G/5G failover if the main line drops.
Think about power. nbn says equipment connected over its network will not work during a power blackout, and it doesn't provide battery backup for your modem or router. A small UPS buys breathing room.
Can you keep your phone numbers when you switch?
Yes. Under the ACMA's Telecommunications Numbering Plan 2025, landline numbers, 1800 freephone numbers, 13 and 1300 local rate numbers and mobile numbers are portable. Your current provider must do everything necessary to port a number when your new provider asks at your request, and must not let anything it does, or fails to do, stop you keeping it.
Your new provider lodges the port request with the old one. Most trouble comes from three things:
Details that don't match
Microsoft's porting guidance, written for its own calling service, names mismatched account details, such as the account number, authorised contact or service address, as the most common cause of errors and delays.
Cancelling too early
Disconnected numbers can't be ported, so leave the old service running until every number has moved.
Forgotten lines
Fax numbers, old direct lines and lines feeding alarms or lift phones are easy to miss, and other services tied to a ported number, such as broadband, can disconnect when the port completes.
How do 000 calls work on a cloud phone system?
Under the ACMA's Emergency Call Service Determination, your provider must, as far as practicable, pass on the calling number with every emergency call, along with the most precise location information available. Separately, the service address you give your provider for each number goes to the Integrated Public Number Database, which the 000 operator can access, so update it whenever numbers move office.
- Power cuts. The Determination lists customer equipment failing in a mains power outage among matters beyond a provider's control. nbn recommends keeping a charged mobile handy and asking the supplier of any medical alarm, fire alarm or lift emergency phone how it will keep working.
- Staff away from the office. A softphone works anywhere, but its registered address may still be the office. Microsoft advises assigning an emergency address to every Teams user; Key IT sets one for each office as part of a Teams Voice setup.
How do you keep a cloud phone system secure?
The classic attack is toll fraud: criminals get in through a weak or default password and rack up overseas calls billed to you. A 2016 Tasmania Police alert described Hobart businesses whose phone systems were hijacked at night or over weekends, one hit by 673 calls in a single night costing more than $9,000.
Lock down 3CX and hosted PBX accounts
Long, unique extension and voicemail PINs, two-factor authentication on the admin console, and international dialling limited to countries you actually call.
Put MFA on every Teams user
Teams Phone is only as secure as each person's Microsoft 365 account. Microsoft's security defaults make every user register for multifactor authentication, and they also block device code flow.
Plan how Teams desk phones sign in
Some Teams devices use device code flow, a sign-in method attackers abuse. Microsoft advises blocking it wherever possible, with a narrow exception for Teams device accounts, so check how handsets sign in before you buy; our guide to device code phishing explains the risk.
Agree a call-back rule
Any request to change bank details, by email or by phone, gets checked by calling a number you already hold; see how a deepfake voice scam unfolds.
Key IT's security-certified engineers lock down admin access, extension passwords and overseas dialling at setup and keep the software patched. For managed clients, Microsoft 365 sign-ins are also covered by Key IT's 24/7 SOC monitoring.
What should be on your migration checklist?
List every number, including fax, 1300 and 1800 numbers and lines used by alarms or lifts.
Gather a recent bill, account numbers and contract end dates, so early termination fees don't surprise you.
Map your call flow
Who answers first, what callers hear and where calls go after hours.
Test the network
Upload speed, Wi-Fi at desks, VPN settings and a static IP.
Plan for outages with failover, diversion to mobiles, a UPS and a charged mobile for 000.
Set emergency addresses for each office and check the service address on every number.
Secure it before go-live with MFA, strong PINs and dialling restrictions.
Port on a quiet day, keeping the old service active, then test calls both ways on every number.
How does Key IT handle the move?
Key IT runs a five-stage project: review your calls, contracts, handsets and network; design the platform and call flows; arrange business NBN or fibre with failover where needed; port your numbers on a date agreed with you, once handsets and apps are ready; then walk staff through it and hand over to the helpdesk. Compare platforms on our business phone systems page, or see how a 3CX setup with Key IT works.
Frequently asked questions
How much does a cloud phone system cost for a small business?
Teams Phone is a per-user monthly licence plus a telco calling service; 3CX is one annual licence for the whole system plus call charges; a hosted PBX is normally a monthly fee per seat. Handsets are extra. Key IT quotes per seat so you can compare the total with your current phone bill.
Can we keep our 1300 number when we move to a cloud phone system?
Yes. The Telecommunications Numbering Plan 2025 makes 13 and 1300 local rate numbers, 1800 freephone numbers, landlines and mobile numbers portable, so your current provider must release them when your new provider requests the port. Key IT moves them across as part of the migration.
Is Teams Phone included in Microsoft 365 Business Premium?
No. Teams Phone Standard is a separate add-on licence that Microsoft lets you add to Business Basic, Business Standard or Business Premium. In Australia you also need a calling service, such as Operator Connect or Direct Routing. Key IT reviews your Microsoft 365 plans and adds Teams Phone licences only where staff need them.
What happens to our phones if the internet goes down?
Calls can keep coming in. Staff can answer in the Teams or 3CX app over mobile data, the system can forward incoming calls to mobiles, and a 4G/5G backup link can keep the office connected until the main service is fixed. Key IT designs these fallbacks in at setup rather than adding them after an outage.
Who supports a cloud phone system after the switch?
With Key IT, the same team that manages your PCs, network and Microsoft 365 handles your phones, on one number: 1300 053 948. The helpdesk runs weekdays from 8am to 5pm, and for managed clients, urgent after-hours problems reach the engineer on the rotating on-call roster.
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