Australia's copper telephone network is being progressively decommissioned as the NBN rollout completes across the country. For most Adelaide businesses, the NBN has been available for years — but not every business has fully migrated away from copper-based services. If your business still has active ADSL internet, PSTN landline phone connections, or ISDN services, you need to be aware of the timelines and what happens when the cutoff arrives.
What's being switched off and when
Telstra's copper infrastructure — the PSTN (public switched telephone network) used for traditional landlines, and the ADSL/ADSL2+ internet services that ran over it — is being progressively disconnected in areas where the NBN has been fully operational. The process is tied to the NBN rollout: once NBN Co declares an area "Ready for Service," the clock starts on a migration window. In most areas, businesses have 18 months from that declaration to complete their migration to NBN-based services before Telstra's copper is terminated.
When that termination date arrives, the consequences are immediate: existing phone lines stop working, ADSL internet stops working, and any fax lines or alarm systems connected to copper PSTN circuits stop working. There's no grace period after the disconnection date.
The NBN rollout across Adelaide's metropolitan area is effectively complete. This means the migration window is real, current, and in some cases already well advanced for businesses that have delayed. If you're still operating ADSL internet at an Adelaide business premises, the clock has been running for some time. ISDN services are in a similar or more advanced stage of decommissioning — Telstra began that process in 2019.
What about copper-based NBN connections like FTTN?
It's worth clarifying a point that creates confusion: FTTN (Fibre to the Node) NBN connections use copper wire for the segment between the street node and your building — but this is NBN Co's infrastructure, not Telstra's copper telephone network. The FTTN copper isn't being disconnected.
What IS happening with FTTN is a progressive upgrade program. NBN Co is working through eligible FTTN premises and offering free upgrades to FTTP (full fibre to the premises). When an upgrade becomes available at your address, you can choose to take it — your FTTN connection continues working in the meantime. The upgrade brings a meaningful performance improvement: full FTTP eliminates the copper segment entirely and unlocks higher speed tiers. Our FTTP upgrade page covers the process and how to check your eligibility.
Phone systems and the copper switch-off
For many Adelaide businesses, the most pressing copper switch-off issue isn't internet — it's phone lines. Businesses that built their telephony on ISDN or PSTN infrastructure have had those services actively decommissioned, and the migration to VoIP over NBN isn't something that can be done quickly or left until the last moment.
The critical detail is porting timelines. Transferring business phone numbers from ISDN (a CAT-C port) takes 8 to 12 weeks. This is not a process that can be rushed — it requires coordination between carriers, paperwork, and scheduling. If your copper service is terminated before the port is complete, you risk losing your business phone numbers entirely. Numbers your customers have been calling for years, your printed materials, your website, your Google Business listing — gone, because the migration wasn't started early enough.
Migrating to VoIP over NBN replaces everything ISDN delivered, typically at lower cost and with considerably more features — call recording, auto-attendants, mobile integration, soft phones, and far more flexible call routing. See our Cloud PBX and SIP Trunks pages for how these services work. But the technical capability of VoIP isn't the concern — the concern is starting the process in time.
What Adelaide businesses should do now
If you're not certain whether your business has any remaining copper-dependent services, that's the first thing to establish. It's more common than businesses expect — a fax line that's been sitting quietly in the background, an ADSL connection at a satellite office, an old ISDN circuit that hasn't been cancelled. An audit of your existing telco services takes a few minutes and removes the uncertainty.
From there, the steps are straightforward:
- Confirm whether your business has any active ADSL internet, PSTN landlines, or ISDN services
- Check your NBN status and whether an FTTP upgrade is available at your address
- If you have ISDN or PSTN phone lines, begin the migration planning immediately — don't wait for a notice letter to arrive
- Ensure any phone numbers being ported have the process started well in advance of any disconnection deadline
Caznet can manage the entire process from the initial audit through to cutover. We'll identify what services you have, confirm your NBN status, coordinate the number porting, and handle the transition without disrupting your operations. Call our team to get started.