Glossary
NBN voice
Voice calling delivered over the Australian National Broadband Network using VoIP/SIP - the standard for Australian business telephony since copper PSTN decommissioning.
also known as: VoIP over NBN, NBN telephony, NBN phone
NBN voice is voice calling delivered over the Australian National Broadband Network using VoIP/SIP protocols, rather than over the legacy copper PSTN.
Why NBN voice replaced copper
The Australian Government progressively decommissioned the legacy copper PSTN as the NBN rolled out. For most Australian premises, traditional copper voice services are no longer available - all voice must come via VoIP over a broadband connection (NBN or alternative).
How NBN voice works
The connection path:
- Your phone system (3CX) or handset sends [[sip|SIP]] messages and [[rtp|RTP]] audio over your NBN connection.
- The traffic flows to your SIP trunk provider over the internet.
- The provider connects to the public phone network.
There’s no special “voice line” - just internet bandwidth carrying voice packets.
NBN connection types and call quality
| NBN type | Voice quality |
|---|---|
| FTTP (Fibre to the Premises) | Excellent - best quality, lowest jitter |
| FTTC (Fibre to the Curb) | Very good |
| HFC (Hybrid Fibre Coaxial) | Good |
| FTTN (Fibre to the Node) | Variable - depends on copper length to node |
| Fixed Wireless | Good in most cases; weather-affected |
| Satellite (Sky Muster) | Acceptable but high latency |
For business voice, FTTP, FTTC, HFC and shorter-distance FTTN typically deliver excellent voice quality. Long-distance FTTN and Sky Muster have inherent latency that can affect call quality.
Speed tier recommendations
- Under 10 users - NBN 25/5 minimum; NBN 50/20 preferred.
- 10–40 users - NBN 50/20 minimum.
- 40+ users or contact centre - NBN 100/40 or business-grade fibre.
- High-volume contact centre - dedicated business fibre or NBN Enterprise Ethernet.
QoS - Quality of Service
Voice packets should be prioritised over other traffic on your network. Modern business routers (Cisco Meraki, Fortinet, Mikrotik, Ubiquiti, pfSense) support QoS policies for SIP/RTP traffic. Standard config; we provide templates.
Backup and resilience
For business-continuity-critical voice:
- Failover internet - second connection (4G/5G or alternative carrier) that voice can fall back to.
- Mobile-app failover - staff can take calls on the 3CX mobile app over 4G/5G if office NBN fails.
- Cloud PBX hosting - the PBX lives in a data centre, so an office outage doesn’t take down the phone system, just access from that site.
