Emergency calling has had more public attention in the last couple of years than in the previous twenty — major network outages where Triple Zero calls didn't connect, the reviews that followed, and a steady stream of carrier messaging about how 000 works. One result is that most people now know roughly what their mobile does in an emergency: if their own carrier's network isn't available, the handset temporarily borrows another carrier's network to place the call. That's emergency camp-on. It's automatic, it costs nothing, and it works even with no SIM in the phone.
None of that applies to a business phone system. A VoIP desk handset, a softphone on a laptop, a calling app on a mobile, or Microsoft Teams Calling has no other network to borrow, no independent power, and no way to tell the operator where you actually are beyond an address someone typed into a database months ago.
To be clear up front: Triple Zero calls from a business phone system do work, and they're free. With the internet up and the power on, the call is carried like any other. The question isn't whether it works on a normal day. It's what happens on the day something has already gone wrong — which, in an emergency, is usually the day you're dialling.
What the mobile network does that a phone system can't
Camp-on is only part of it. A mobile placing a 000 call has three protections that simply have no equivalent on a business phone system: it can use any carrier's network rather than only yours, it carries its own power, and it tells the emergency service where it physically is rather than relying on an address held in a database. Take those away one at a time and you have the shape of the problem.
Everything on a phone system depends on a working data path back to that system. Lose it and there is no second network waiting to pick up the call — no camp-on, no borrowed carrier, nothing. The call simply doesn't go. And "lose it" covers more ground than an NBN outage: a failed router, a power cut in the comms cabinet, a home internet dropout, an office Wi-Fi network that's gone down with everything else.
Location is the part that surprises people most, and it applies even when everything is working perfectly. A mobile sends handset-derived location to the emergency service. A VoIP call sends a number, and the operator looks up the address registered against it — more on that below.
The old copper phone line sat somewhere in between. It had no location intelligence either, but it drew its power from the exchange, so it kept working through a blackout. That property has quietly disappeared from most Australian offices as copper was retired — see the NBN copper switch-off and what it means for your business. Plenty of businesses replaced their phone system without ever noticing that a backstop had gone with it.
Problem 1: no internet or no power means no 000
A cloud phone system puts the intelligence in a data centre with redundant power and connectivity. That's a good thing — but the last-mile link between your office and that data centre is a single point of failure, and so is the power feeding your comms cabinet.
Desk phones are powered over the Ethernet cable by a network switch. That switch needs mains power. So does the router, and so does the NBN network termination device on the wall. Lose power and the phones go dark almost immediately. Lose the internet — a fibre cut, an NBN outage, a failed router — and the handsets stay lit but can't place a call to anyone, Triple Zero included.
You can reduce the exposure, but not eliminate it:
- A UPS on the comms cabinet — switch, router and NBN NTD — keeps phones alive for minutes to an hour, depending on sizing. Useful for a brief flicker or a controlled evacuation. It is not a day's worth of protection, and it does nothing if the outage is upstream at the exchange or in the street.
- 4G or 5G failover covers the internet leg. If the router is on the UPS and has a mobile backup SIM, calls keep flowing through a fixed-line outage. Both conditions need to hold.
- Mobile fallback on the phone system keeps inbound calls reaching your team during an outage — covered in keeping your phones running when the internet drops. It doesn't help someone standing in the building trying to dial out.
Softphones shift the problem rather than removing it. A laptop or mobile has its own battery, so a blackout doesn't kill it outright — but the softphone still needs a working data path. Office Wi-Fi runs off access points that are powered by the same switch as the desk phones, so it goes down with everything else. A mobile app on mobile data survives that, right up until the point where there's no coverage or the app can't reach the phone system.
Problem 2: a calling app on a mobile is not a mobile
This one catches people out precisely because the device in their hand is a phone. Staff with a softphone app or the Teams mobile client have two completely separate ways to make a call, and only one of them has the emergency behaviour described above.
| Dialling 000 from… | What happens |
|---|---|
| The mobile's own dialler | Native emergency handling: camp-on to any available network, works with no SIM, handset-derived location sent to the emergency service |
| The keypad inside a softphone or Teams app | A VoIP call over data or Wi-Fi, carrying your registered service address — no camp-on, no handset location, and nothing at all if the app can't reach the phone system |
Some calling apps are built to recognise an emergency number and hand the call straight to the native dialler. Many aren't, and you can't tell which by looking at the screen. Assuming your app does the right thing is not a plan — and even where it does, the user still has to be in the app, on a device with coverage, thinking clearly.
The same logic applies to desktop softphones, tablets and Wi-Fi-only devices, with fewer escape routes: a laptop softphone in a home office has no cellular fallback whatsoever, and no equivalent of camp-on. If the home internet is out, so is 000 from that client.
There's a corollary worth telling staff explicitly. If someone is somewhere with no usable mobile coverage but working Wi-Fi — a basement office, a thick-walled warehouse — Wi-Fi Calling on the mobile's native service is the better option than the softphone app, because it still routes through the carrier's emergency handling rather than through your business phone system.
Problem 3: the address the operator sees may not be yours
This is the one most businesses have never thought about, and it's the one most likely to bite.
When a 000 call arrives from a fixed or VoIP number, the emergency operator looks that number up in the Integrated Public Number Database (IPND) — a national database every carrier is legally required to populate — and sees the service address registered against it. That address is a record, not a measurement. Nothing about the call itself reveals where the phone is.
Several perfectly ordinary business setups break that assumption:
| Situation | What the operator may see |
|---|---|
| One number range shared across several sites | The single address registered for the range — likely head office, not the site with the emergency |
| All outbound calls present the main business number | The main office address, whichever branch the call came from |
| Staff working from home on a softphone or Teams client | The office address, while the caller is at their kitchen table |
| A softphone or calling app used on the road, at a client site, or interstate | Wherever the account was registered — the device moves, the record doesn't |
| A handset carried to another office or a new desk | The address it was originally registered at |
| The business moved and nobody told the provider | The previous premises |
Microsoft Teams deserves a specific note. Teams lets you set an emergency address per user in the admin centre, and some markets support dynamic emergency calling that detects which network a client is connected to. In an Australian deployment the address that reaches the operator still depends on what your carrier has registered in the IPND against the number the call presents. A location set inside Teams doesn't automatically become the location the Triple Zero operator sees. If emergency calling matters to how your business runs — and it should for anyone with staff in the field, on multiple sites, or working from home — this is worth confirming explicitly with whoever provides your Teams calling, rather than assuming.
Problem 4: the dial plan itself
A smaller issue, but a real one. Many phone systems are configured to require a prefix — usually 0 or 9 — for an outside line. Staff who've internalised that habit may dial 0-000, or dial 000 and get nothing, at exactly the wrong moment.
Any properly configured system should pass a bare 000 straight through with no prefix, from any handset, on any extension, regardless of whether that extension is otherwise barred from making outbound calls. Reception phones, lobby phones, warehouse phones and lift phones are all worth checking, because they're the ones most often restricted to internal calls only.
It's also worth knowing that 112 is a mobile emergency number recognised by GSM handsets worldwide — it is not a magic alternative on a fixed or VoIP line. On a business phone system, 000 is the number that matters.
The practical checklist
- Register a service address for every physical site, not one address for the whole account. If you have three offices, your provider should hold three addresses against the relevant numbers.
- Give each site its own outbound caller ID. Presenting the head office number on every call across the business is tidy for marketing and wrong for emergencies.
- Update the address whenever you move — including a move within a building complex, if the street address or unit number changes. Under our standard terms, we register your service address with the Emergency Call Person, and you need to tell us promptly when it changes. That clause exists for exactly this reason.
- Display the full street address near the phones and at reception, including unit or level number. Even with the right address on file, the operator will ask the caller to confirm it, and people forget their own address under stress.
- Check that 000 dials without a prefix from every handset, including restricted extensions.
- Give softphone and Teams users one clear rule: for 000, use the phone's own dialler, never the keypad inside the app. It's a single sentence, and it's the highest-value thing on this list for anyone whose staff aren't at a desk.
- Keep an emergency address current for every softphone user, including home-based staff, and treat a change of home or site as something worth telling you about.
- Make sure each site has a known mobile and that staff know whose it is — the practical answer when there's no dial tone.
- Put a UPS on the comms cabinet if losing phones during a blackout would be a safety issue, not just an inconvenience. Size it deliberately and test it once a year.
- Review it annually. Addresses, sites and staff arrangements change more often than phone systems do.
Bottom line
VoIP, softphones and Teams calling are better than the phone systems they replaced in almost every way that matters day to day. Emergency calling is the one area where something was genuinely lost: the line power that kept a copper phone alive in a blackout, and a network that falls back automatically the way a mobile does. Neither is a reason to stay on old technology — but both are reasons to make two things true in your business. Staff should know that 000 goes through the mobile's own dialler, not the desk phone and not the app. And the address on file against your numbers should be the address someone would actually be standing at when they call.
If you're not certain what's registered against your numbers, or whether each of your sites presents its own caller ID, get in touch or call 1300 229 638 and we'll check it with you.
Mobile emergency camp-on is implemented by all Australian mobile network operators; exact on-screen indicators and connection times vary by handset and network. IPND and Emergency Call Person obligations arise under the Telecommunications Act 1997 (Cth) and associated instruments. This article is general information about how business phone systems behave and is not advice about what to do in an emergency — in an emergency, call 000 by whatever means is available. For official guidance on reaching Triple Zero, see triplezero.gov.au.