What Is a Hosted PBX?

If your business is still running an on-premise phone system — or you're being told your ISDN lines are getting switched off — you've probably heard the term Hosted PBX thrown around. But what does it actually mean, what does it cost, and is it the right move for your business?

This guide covers everything you need to know, written by the telephony team at Synex Technology — an Australian MSP that designs, migrates, and manages Hosted PBX systems for businesses across the country.

What is a Hosted PBX?

A Hosted PBX (Private Branch Exchange) is a cloud-based business phone system where the PBX infrastructure — the hardware, software, and call routing logic — lives in a data centre managed by your provider, not on your office premises. Your phones and devices connect to it over the internet using VoIP (Voice over IP) technology.

Think of it this way: instead of owning a bulky phone cabinet in your server room that costs tens of thousands of dollars and requires a specialist to maintain, you subscribe to a fully managed phone system in the cloud. You pay per user, per month. The provider handles all the infrastructure, updates, and uptime.

Quick definition: Hosted PBX = all the power of a traditional office phone system, delivered from the cloud, managed by your MSP. No server cabinet. No maintenance contracts. No surprise hardware failures.

Popular Hosted PBX platforms used by Australian businesses include 3CX, Microsoft Teams Phone System (with Direct Routing or Operator Connect), RingCentral, and carrier-hosted platforms via providers like Symbio and Vonex. At Synex Technology, we deploy and manage all of these depending on client requirements.

How does a Hosted PBX work?

When you make or receive a call on a Hosted PBX, here's what happens under the hood: 1. Your phone or softphone app connects to the cloud PBX — using SIP (Session Initiation Protocol) over your internet connection — NBN, fibre, or 4G failover. 2. The PBX platform processes the call in the cloud — your IVR menu, hunt groups, call queues, and routing rules are all applied instantly. No local hardware involved. 3. The call reaches its destination via SIP trunking — outbound calls exit through SIP trunks connected to the PSTN. Calls between internal extensions are free — they never touch the public phone network. 4. Your admin portal gives you full control — add users, change call flows, update opening hours, pull call reports — all from a browser, no technician required.

Synex Tip: For best voice quality over NBN, Synex Technology configures QoS (Quality of Service) on your firewall to prioritise SIP/RTP traffic. On an NBN Fibre 100 or better connection, call quality is indistinguishable from a traditional landline.

Hosted PBX vs traditional PBX: what's the difference?

If you're still running an ageing on-premise PBX — a Panasonic KX, NEC, or similar cabinet system — here's an honest comparison of what you're currently living with versus what a Hosted PBX delivers.

Upfront cost: Traditional PBX $5,000–$50,000+ hardware vs Hosted PBX $0 upfront, monthly subscription. Ongoing cost: Traditional PBX high (maintenance, hardware refreshes) vs Hosted PBX predictable per-user monthly fee. Scalability: Traditional PBX requires hardware purchase to add lines vs Hosted PBX add/remove users instantly via portal. Remote work: Traditional PBX limited, often requires VPN or ISDN vs Hosted PBX full features on any device, anywhere. Maintenance: Traditional PBX your responsibility or expensive contracts vs Hosted PBX managed by your MSP and provider. Disaster recovery: Traditional PBX single point of failure on-site vs Hosted PBX automatic failover in the cloud. Feature updates: Traditional PBX manual firmware upgrades, often skipped vs Hosted PBX automatic, always on latest version. CRM integration: Traditional PBX limited or requires expensive middleware vs Hosted PBX native integrations with M365, Salesforce, HubSpot.

Key features of a Hosted PBX system

Modern Hosted PBX platforms go well beyond basic inbound and outbound calling. Here are the features Australian businesses rely on most: Auto-attendant / IVR — professional multi-level menus that route callers to the right team 24/7, without needing a receptionist. Hunt groups & call queues — ring multiple extensions simultaneously or in sequence; hold callers in a queue with music or messaging. Softphone & mobile app — your office number rings on your laptop or smartphone so your team can work from anywhere. Voicemail to email — voicemails delivered as audio file attachments directly to your inbox. Call reporting & analytics — inbound volumes, answer rates, wait times, and agent performance — all in a live dashboard. Call recording — record calls on-demand or automatically per extension for compliance, QA, or training. Time-of-day routing — after-hours calls automatically route to voicemail, an answering service, or a mobile. CRM screen-pops — when an inbound call arrives, your CRM (Salesforce, HubSpot, etc.) automatically surfaces the caller's record. Video conferencing — built-in video meetings via 3CX or Microsoft Teams with no extra subscriptions required. Number portability — keep your existing geographic (02/03/07/08) and 1300/1800 numbers. They come with you.

Why Australian businesses are switching to Hosted PBX

1. The ISDN/PSTN sunset is forcing a change anyway

Telstra has been progressively retiring legacy ISDN and PSTN services across Australia. If your on-premise PBX relies on ISDN lines, you will need to migrate. The question is whether you replace like-for-like — or take this opportunity to move to the cloud and never deal with legacy telecoms infrastructure again.

2. Hybrid and remote work is now permanent

A traditional PBX was built for one physical location. Today's workforce expects to take their extension home, answer calls on a mobile, and join meetings from a laptop. Hosted PBX delivers this natively — your phone system follows your team, not the other way around.

3. No capital expenditure

For Australian SMBs, a Hosted PBX moves telephony from a capital expenditure (CapEx) to a predictable operational expenditure (OpEx). No large upfront hardware cost, no depreciation headaches, and no surprise maintenance bills when a board fails at 4pm on a Friday.

4. Business continuity built in

Your office loses power or internet? With a properly designed Hosted PBX, calls automatically route to mobile apps or alternative extensions. The system runs on geographically redundant cloud infrastructure — it keeps going whether your office does or not.

5. Scales with your business

Opening a new branch in Brisbane while you're headquartered in Melbourne? Add a new 07 number and extensions in minutes from the same admin portal. No hardware shipped, no technician visit.

Real-world result: A 25-seat professional services firm in Melbourne was spending over $2,400/month on an ageing ISDN-backed on-premise PBX — including line rental, maintenance contracts, and handset refresh cycles. After migrating to a Hosted PBX with Synex Technology, their total monthly telephony cost dropped to under $900/month, with better features and a fully managed service. That's over $18,000 saved per year.

Which Hosted PBX platform is right for your business?

There's no single right answer — it depends on your team size, existing Microsoft or Google stack, and how much administrative control you want. Here's how Synex Technology thinks about platform selection: 3CX — best for businesses wanting a full-featured, cost-effective cloud PBX with deep control over call flows. Excellent for 10–500 seat environments. Strong softphone, web client, and mobile apps. Microsoft Teams Phone System — ideal if your team is already on Microsoft 365. Direct Routing or Operator Connect adds full PSTN calling to Teams. One client for calling, chat, and video meetings. RingCentral / 8x8 — suited to businesses wanting a fully integrated UCaaS platform with built-in contact centre features, at a higher per-seat cost. Carrier-hosted PBX — a simpler option for smaller businesses (under 10 seats) who want basic features without the management overhead of a full platform.

Not sure which platform suits you? Synex Technology provides a free telephony assessment — we audit your current phone system, call volumes, and business requirements, then recommend the right platform with a clear migration plan and cost comparison.

How to migrate to a Hosted PBX: what to expect

A well-planned migration to a Hosted PBX should be seamless — zero downtime, no dropped calls, and no disruption to your team. Here's how Synex Technology runs a typical migration: 1. Discovery & design — we audit your current phone system, document all DDIs, extensions, call flows, IVR scripts, and opening hours. We identify QoS requirements for your existing network. 2. Platform provisioning & testing — we build and test your Hosted PBX environment in full — including all call flows, auto-attendants, hunt groups, and voicemail — before a single live call is moved. 3. Number porting (LNP) — we initiate the Local Number Portability process with your current carrier. Your existing geographic (02/03/07/08) numbers come with you. No new number, no reprinting of business cards. 4. Device deployment — desk phones (Yealink, Poly, Cisco) are provisioned via zero-touch — plug in and they auto-configure. Softphones are deployed to laptops and mobiles via MDM. 5. Cutover & ongoing support — we cut over during a low-traffic window, train your team on the new system, and provide ongoing managed support. Synex Technology is your single point of contact for all telephony issues going forward.

How much does a Hosted PBX cost in Australia?

Hosted PBX pricing in Australia is structured as a per-user monthly fee. As a rough guide: Basic (calls + softphone only): $15–$25 per user/month. Standard (calls, voicemail, mobile app, CRM integration): $25–$45 per user/month. Premium (contact centre features, analytics, call recording): $45–$80 per user/month. SIP trunking / call costs: $0.01–$0.04 per minute for Australian local/national calls, depending on volume.

Add to this the cost of desk handsets if required (typically $120–$350 per handset, one-off), network QoS configuration, and an initial setup/migration fee depending on complexity.

Important: When comparing costs, always include what you're currently spending — line rental, hardware maintenance, licensing, and the hidden cost of managing an ageing system in-house. In most cases, a Hosted PBX delivers a better total cost of ownership within the first 12 months.

Frequently asked questions about Hosted PBX

Can I keep my existing business phone numbers?

Yes. Local Number Portability (LNP) in Australia allows you to keep your existing 02, 03, 07, 08, and 13/1300/1800 numbers when migrating to a Hosted PBX. Synex Technology manages the entire porting process — we coordinate directly with your current carrier so you don't have to.

Does a Hosted PBX work with NBN?

Yes — and it's the recommended approach. NBN has effectively replaced ISDN as Australia's primary broadband infrastructure. A Hosted PBX over a well-configured NBN connection (with QoS prioritisation) delivers excellent call quality. Synex Technology typically recommends NBN 50 or above for voice deployments.

What happens to calls if our internet goes down?

With a properly designed Hosted PBX, calls automatically failover to mobile apps. Synex Technology also recommends a 4G LTE failover connection for business-critical environments — this kicks in automatically if your primary NBN circuit drops, keeping your phones online.

Do I need to replace all my existing desk phones?

Not necessarily. Many modern SIP-compatible desk phones (Yealink, Poly, Cisco) can be reprogrammed to work with a Hosted PBX. Synex Technology will audit your existing hardware and advise what can be reused versus replaced. For many businesses, the savings on line rental alone are enough to fund any necessary handset upgrades.

Is a Hosted PBX secure?

Yes — when configured correctly. Synex Technology implements SIP TLS and SRTP encryption for all voice traffic, restricts SIP access via firewall rules, and configures Session Border Controllers (SBCs) where required. We also actively monitor for toll fraud — a real risk on poorly secured SIP deployments.

How long does migration take?

A typical SMB migration (10–50 seats) takes 2–4 weeks from engagement to cutover, including discovery, platform build, testing, number porting, and device deployment. Larger or more complex environments take longer, but we plan every migration to ensure zero downtime and minimal disruption to your team.

Why choose Synex Technology for your Hosted PBX?

Synex Technology is an Australian MSP with deep expertise in business telephony. We're not a reseller who hands you a login and leaves you to it — we design, deploy, and manage your phone system as part of a fully managed service.

Platform agnostic — we recommend the right solution for your business, not the one with the best reseller margin. End-to-end managed — from network QoS and SIP security through to handset provisioning and user training. Australian-based support — local team, local time zones, real people answering the phone when something goes wrong. Integrated with your IT — as your MSP, we align your phone system with Microsoft 365, your firewall, your NBN connection, and your broader business processes. Transparent pricing — fixed monthly costs with no hidden call charges or surprise bills at the end of the month.