What You Will Need
Before starting, confirm you have: an active NBN connection (any technology type), a router with QoS (Quality of Service) support, SIP desk phones or softphone applications, and your VoIP provider account credentials (SIP username, SIP password, SIP server address). If you are using a hosted PBX service, your provider should supply the SIP credentials and any required provisioning instructions.Step 1: Check Your NBN Connection Type
Your NBN connection type determines the baseline quality and reliability you can expect for VoIP. You can find your connection type on your NBN provider's account portal or by checking the NBN address checker at nbnco.com.au.| FTTP (Fibre to the Premises) | FTTC (Fibre to the Curb) | HFC (Hybrid Fibre Coaxial) | FTTN (Fibre to the Node) | FTTB (Fibre to the Building) | Fixed Wireless | Sky Muster Satellite | |
|---|---|---|---|---|---|---|---|
| VoIP Suitability | Excellent | Very good | Good | Variable | Good | Moderate | Poor |
| Notes | Best option. Low, consistent latency. | Consistent for most deployments. | Some peak-hour variation. Generally reliable. | Quality depends on copper run length. Test before committing. | Similar to FTTC in practice. | Latency higher than fibre. Test with your provider. | High latency unsuitable for real-time voice. |
Step 2: Test Your Connection Baseline
Before configuring VoIP, measure your connection's latency and packet loss. VoIP requires latency below 150ms and packet loss below 1% for acceptable quality. Use a connection quality test that includes jitter and packet loss metrics. A standard speed test is not sufficient.Tools: ping test to your VoIP provider's SIP server (ask them for the server IP), or use a service like Cloudflare's speed.cloudflare.com which measures latency and jitter. Run the test during your busiest business hours to measure worst-case performance.Step 3: Configure QoS on Your Router
Quality of Service (QoS) settings on your router prioritise voice traffic over other internet traffic. Without QoS, a large file download or video stream from another device on your network can cause noticeable quality degradation during calls.Most business-grade routers (Ubiquiti, Cisco, MikroTik, Netgear Business) support QoS configuration. Consumer-grade routers vary: check your router's manual for 'QoS' or 'traffic prioritisation' settings. The specific configuration depends on your router model, but the general approach is to create a high-priority rule for SIP traffic (UDP port 5060) and your VoIP provider's RTP audio traffic range.Step 4: Configure Your SIP Phones
If you are using a hosted PBX service, your provider will typically either pre-configure your phones before shipping them, or supply a provisioning URL that auto-configures the phone when it connects to your network. Follow your provider's provisioning guide.The simplest option for a small business without IT staff is to order pre-configured phones directly from your hosted PBX provider. They arrive ready to plug in. No provisioning steps, no SIP credentials to enter manually, no settings to configure. Your provider is responsible for making the phones work with your service from the moment you plug them in. Use the manual configuration path below only if your provider does not offer pre-provisioning, or if you are adding phones to an existing setup later.If you are configuring phones manually, you will need to enter: SIP server address (provided by your hosted PBX provider), SIP username (your extension or DID number), SIP password, and codec preferences. For Australian NBN connections, G.711 (ulaw/alaw) or G.722 are the recommended codecs. G.722 provides wideband HD audio where supported. Avoid G.729 where possible as it increases latency and degrades under packet loss.Step 5: Test Calls and Verify Quality
After configuration, test inbound and outbound calls. Check: call setup time (should be under 3 seconds), audio quality in both directions, whether calls drop when switching between speakers or on hold, and behaviour during a simultaneous internet-heavy task (simulate by running a speed test during a call).If you are using a hosted PBX system, most providers offer an echo test number or call quality diagnostic you can use to verify your setup before going live.Troubleshooting Common Issues
Common VoIP quality issues on Australian NBN connections and their causes:| Choppy audio / robotic voice | Calls drop after 30 seconds | One-way audio | Calls not connecting | Echo on calls | |
|---|---|---|---|---|---|
| Likely Cause | Packet loss or jitter on NBN connection | NAT/firewall issue with SIP | Firewall blocking RTP audio ports | SIP registration failing | Acoustic echo on handset |
| Fix | Check NBN line quality, enable QoS, check for interference on FTTN copper | Enable SIP ALG workaround or check provider's NAT settings | Open RTP port range in your router firewall (ask provider for their range) | Check SIP credentials, verify firewall is not blocking port 5060 | Use handset in a quieter environment or check headset configuration |
SIP ALG: The Hidden Router Setting That Breaks VoIP
SIP ALG (Session Initiation Protocol Application Layer Gateway) is a feature built into most consumer and small business routers. It was designed in the early days of VoIP to help route SIP traffic through NAT (Network Address Translation). In practice, it causes far more problems than it solves on modern VoIP systems, and is the single most common cause of unexplained VoIP call quality issues and registration failures in Australian SMB deployments.
When SIP ALG is enabled, your router intercepts SIP packets and modifies the internal IP addresses within them, attempting to translate them for external routing. The problem is that modern hosted PBX providers already handle NAT traversal correctly in their platform. When the router also tries to modify the packets, it creates conflicts: calls that connect but drop within seconds, one-way audio where you can hear the other party but they cannot hear you, phones that fail to register with the PBX, or calls that fail to ring through at all. These symptoms are often misdiagnosed as ISP issues, NBN problems, or faulty phones. They are frequently SIP ALG.
To disable SIP ALG, access your router's administration interface (typically at 192.168.1.1 or 192.168.0.1 in your browser). Look in the Advanced, Firewall, or NAT settings for "SIP ALG", "SIP Inspection", "SIP Helper", or "Application Layer Gateway". Disable all SIP-related options and save. Restart the router. If you cannot find the setting in your router's interface, search for your router model and "disable SIP ALG" for model-specific instructions. After disabling, re-register your phones and test calls again before assuming the problem is elsewhere.
Check SIP ALG first, always. Before spending time on NBN line testing, codec changes, or router QoS configuration, confirm SIP ALG is disabled on your router. It costs two minutes and eliminates the most common cause of VoIP setup problems. Your VoIP provider should tell you this during setup, but not all of them do.
Separating Your Voice Traffic With a Dedicated VLAN
A VLAN (Virtual Local Area Network) allows you to segment your office network so that voice traffic and data traffic travel on separate logical networks, even though they share the same physical switches and cables. For most small businesses with one to five staff on a reliable FTTP or HFC NBN connection, a VLAN is not necessary. QoS on the router is sufficient. However, for businesses with six or more staff, high call volumes, or an FTTN connection with variable quality, a voice VLAN is worth implementing.
The benefit of a voice VLAN is isolation. Data traffic (file downloads, video streaming, cloud backups, software updates) cannot compete with voice traffic for bandwidth at the switch level. Each traffic type stays in its own lane. This eliminates the most common cause of in-office call quality issues that persist even when QoS is configured: a large file transfer or backup job saturating a switch port and causing momentary drops in voice packet delivery.
Setting up a voice VLAN requires a managed network switch (not a standard consumer switch) and a router that supports VLAN tagging. Your VoIP phones need to be configured to tag their traffic with the correct VLAN ID. Most enterprise-grade SIP phones, including all current Yealink and Grandstream models, support VLAN configuration. If you are deploying PoE phones through a managed switch, your IT contact or your VoIP provider's support team can assist with the configuration. This is not a task for a first-time setup without technical guidance, but it is a one-time configuration that improves voice quality permanently once done.
000 Emergency Calling on VoIP
Unlike traditional landlines, VoIP services do not automatically provide location information to emergency services when you dial 000. Under ACMA regulations, VoIP providers must allow 000 calls, but the caller location may not be accurately transmitted. If your business relies on phone-based emergency access (medical practices, aged care, childcare centres), confirm with your provider how 000 calls are handled and whether location data is passed. Consider maintaining a mobile phone as a backup for emergency calls.Power Outages and VoIP on NBN
Unlike the old copper PSTN, your NBN connection and VoIP phones require mains power. When the power goes out, your phones go down. This is a critical consideration for businesses.Your options:1. UPS (Uninterruptible Power Supply): A small UPS ($150-300 AUD) can keep your NBN modem, router, and one or two phones running for 1-3 hours during a blackout.
2. Mobile failover: Most hosted PBX providers can route calls to mobile numbers when your desk phones go offline. Configure this as part of your initial setup.
3. 4G/5G backup: Some routers support a mobile SIM for automatic failover when the NBN connection drops.
Working With Your VoIP Provider's Support Team
When things go wrong with a VoIP setup, the quality of your provider's support is the difference between a problem resolved in an hour and a problem that drags on for days while you are fielding frustrated customer calls. Understanding what information your provider needs, and what constitutes good support versus inadequate support, helps you get issues resolved faster and helps you choose the right provider from the start.
Before contacting support with a call quality issue, gather the following: your NBN connection type (FTTP, FTTN, HFC, Fixed Wireless), your router make and model, whether SIP ALG is disabled, the specific symptom (one-way audio, dropped calls, echo, choppy audio, failed registration), when it started, whether it affects all phones or specific phones, and whether it happens on all calls or specific destinations. A support team that asks you these questions is diagnosing properly. A support team that immediately tells you "the problem is with your ISP" without asking any of these questions is not.
What good VoIP support looks like: a local Australian team who can have a real conversation about your setup, the ability to check your account's call quality reports (MOS scores, packet loss statistics) from their end, remote phone configuration access if needed, and clear escalation paths if the first-level contact cannot resolve the issue. What poor support looks like: offshore script-readers who cannot interpret your NBN connection details, no visibility into call quality metrics from their platform, and resolution timelines measured in "we will email you within five business days". Choose a provider whose support model matches the importance of the phone system to your business.
Common Setup Mistakes
1. Leaving SIP ALG enabled. This is the number one cause of VoIP problems on Australian NBN connections. SIP ALG (Application Layer Gateway) is a router feature that attempts to help VoIP traffic but almost always makes things worse. Disable it. If your router does not let you disable it, you may need a different router.2. Not configuring QoS. Without Quality of Service rules, a large file download or video stream can consume all your upload bandwidth and destroy call quality. QoS ensures voice packets get priority. This is not optional, it is essential.3. Skipping the connection test before buying phones. Before investing in SIP desk phones, test your NBN connection for jitter, packet loss, and upload speed. If your FTTN connection has less than 5 Mbps upload, you may have issues with more than 3-4 simultaneous calls. Our call quality guide shows you exactly how to test.Your Next Steps
1. Test your connection first. Run a VoIP-specific quality test (not just a speed test). Check upload speed, jitter, and packet loss.2. Disable SIP ALG on your router. Do this before anything else.
3. Configure QoS for voice traffic. Prioritise UDP ports 5060 (SIP signalling) and 10000-20000 (RTP media).
4. Contact a VoIP provider. They will supply SIP credentials, recommend compatible phones, and can often pre-configure handsets before shipping them to you.
5. Plan for power outages. Set up mobile failover in your PBX and consider a UPS for your network equipment.
6. Test thoroughly before porting numbers. Run the new system in parallel for a few days before moving your main business number across.Not sure where to start? Get a free recommendation based on your NBN type and business needs.
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