- What is ending
- ISDN and remaining PSTN business services
- Who it affects
- Anyone with a phone system wired to a wall socket
- Typical notice
- Around 12 months from your carrier
- Time to migrate
- Two to six weeks if you start early
There’s a particular kind of phone call that telecommunications consultants dread making, and it goes like this: the business has had a letter, the letter said something about network modernisation, the letter went in a drawer, and now there are four weeks left.
Australia has been retiring its copper voice services for the better part of a decade. Telstra started disconnecting ISDN services in 2019 and has worked through the base region by region ever since. The 3G networks went in 2024. What is left in 2026 is the long tail: the sites that were too complex, too remote or too quiet to be caught in the earlier waves, plus a surprising number of businesses whose systems were migrated on paper but never in practice.
If your phone system is a box on a wall and the line into it comes out of a socket rather than out of your network switch, this is about you.
Why the letter is easy to ignore
Carrier disconnection notices are written by legal teams. They talk about network transformation programmes and service withdrawal dates. They rarely say the thing that actually matters, which is: on this date your phones stop working and your customers get a dead line.
They also arrive absurdly early. Twelve months of notice sounds generous, and it is, but it means the letter lands in a quarter where nothing is on fire and gets filed accordingly. The businesses that handle this well are the ones that treat the notice as a project trigger rather than as information.
The part nobody budgets for
Replacing the service is the easy half. Every cloud platform in our comparison table will sell you seats, port your numbers and have you taking calls inside a fortnight. The half that catches people out is everything hanging off the old system.
- Handsets. Digital handsets wired to a legacy PBX speak a proprietary protocol and won’t register to anything else. If you’ve thirty desks, that’s thirty replacements, or thirty people working from an app.
- Analogue oddities. The lift phone. The fire panel dialler. The EFTPOS terminal in the back office. The fax line the accountant swears is still needed. Each one is a separate small project and each one is discovered late.
- Number blocks. A 100-number block doesn’t port the way a single service does. Expect more paperwork and more elapsed time.
- Call flow. Twenty years of after-hours rules, department transfers and one-off diversions live inside a box that nobody has documented. Rebuilding it from scratch is often better than replicating it, but it takes a conversation with the people who answer the phones.
What a sane migration looks like
The businesses that come through this without drama tend to do the same five things.
- Find the disconnection date and write it somewhere visible. Call your carrier and get it in writing if the letter is gone.
- Inventory every service on the account, not just the ones people use. The lift phone is always on the list and never in anybody memory.
- Port first, cut over second. Numbers moving to the new platform while the old one still answers gives you a fallback. Doing both on the same morning does not.
- Run both for a week. Overlap costs one month of line rental and buys you the ability to undo a bad Monday.
- Rebuild the call flow rather than copying it. You’re paying for the migration anyway. This is the cheapest chance you’ll ever get to fix the menu that everyone complains about.
The upside nobody mentions
Forced migrations are miserable, but the businesses on the other side of one almost never want to go back. The old system charged per line and capped how many calls you could take at once. The new one doesn’t have a ceiling, costs less per seat than the old maintenance contract, works on a mobile, and answers the phone by itself at 9pm.
The two Australian platforms at the top of our table both include free number porting and free setup, which removes the two line items that usually make a forced migration feel like a punishment. If you’re going to be pushed off copper anyway, being pushed onto something better isn’t the worst outcome available.
The two that topped our 2026 scorecard
Uniden Voice over Cloud scored 95/100 at $34.90 per user per month with calls, AI agents and 40+ call-flow features included. VOCPhone scored 92/100 and is the one to shortlist if the phone is a sales tool.
Questions
How do I know if my business is still on ISDN or copper?
Look at where your phone system plugs in. If handset cabling runs back to a box on the wall or in a cupboard, and that box connects to a socket rather than to your network switch, you’re almost certainly on a legacy service. Your invoice will also name it: ISDN 2, ISDN 10/20/30, PSTN or "business line" are the usual labels.
What happens if I do nothing?
The service stops on the disconnection date and inbound calls fail. Numbers aren’t lost immediately, but recovering a number after disconnection is far slower and messier than porting a working one, and some carriers won’t do it at all.
Can I keep my existing handsets?
Usually not. Digital handsets wired to an old PBX speak a proprietary protocol and won’t register to a cloud platform. Standard SIP handsets will. Budget to replace the fleet, or start on apps and add handsets where a physical phone is genuinely needed.