Why Is My Business Phone Cutting Out? 7 Causes and How to Fix Them

You’re halfway through a sales call. The client is about to say yes. Then — silence. The call drops.

Or maybe it’s not a full drop. The audio goes choppy, your words come out robotic, the other person keeps asking you to repeat yourself. Either way, it looks unprofessional and it costs you business.

Dropped and choppy VoIP calls are one of the most common complaints from Australian businesses — and one of the most fixable. Almost every case comes down to one of seven causes. This guide walks through all of them, with a plain-English diagnosis test and a step-by-step fix for each.

💡  Quick Answer The most common cause of dropping business phone calls in Australia is insufficient upload bandwidth or missing QoS (Quality of Service) settings on your router. Fix those two things first — they solve around 60% of cases. The other five causes are below.

Diagnose Your Problem First — Match Your Symptom

Before reading through all seven causes, use this table to zero in on the most likely culprit based on what you’re actually experiencing:

Symptom you’re experiencing	Most likely cause	First thing to try
Calls cut out after exactly 30 seconds	Cause #4 — SIP ALG	Disable SIP ALG on your router
Audio choppy or robotic	Cause #1 or #2	Run a VoIP speed test, switch to ethernet
One-way audio (you hear them, they can’t hear you)	Cause #4 — NAT/Firewall	Check SIP ALG and firewall rules
Calls drop during busy periods only	Cause #1 or #5	Test bandwidth during peak hours
Calls drop on Wi-Fi only, fine on ethernet	Cause #3 — Wireless	Move calling device to ethernet
Calls drop on all devices equally	Cause #1 or #6	Check NBN connection type and ISP plan
Crackling, static, or echo	Cause #7 — Hardware	Check handset and cables, update firmware
Calls drop after recent router change	Cause #4 — SIP ALG	Disable SIP ALG on new router

If your symptom matches a specific cause, skip straight to that section. If it’s more general — calls dropping randomly with no obvious pattern — read through all seven in order.

The 7 Causes — And How to Fix Them

Cause #1  Not Enough Upload Bandwidth HOW TO DIAGNOSE: Run a speed test at speedtest.net during business hours — specifically check your upload speed, not just download. VoIP calls use roughly 85–100 Kbps of upload bandwidth per simultaneous call. If your office has 10 staff making calls and your upload speed is under 1 Mbps, you’re already over capacity. Test during peak hours (10am–12pm, 2pm–4pm) when NBN node congestion is highest. HOW TO FIX IT: Upgrade to a business-grade NBN plan with a guaranteed upload speed — consumer plans deprioritise upload during congestionEnable QoS on your router to prioritise voice traffic — see Cause #2 below (this alone can resolve choppy calls without a plan upgrade)If you’re on NBN FTTN (Fibre to the Node) and your office is far from the node, your upload speed may be structurally limited — consider upgrading to FTTP or moving to a business fibre connectionCheck your connection type at broadconnect.com.au/business-nbn — FTTP and HFC deliver far better upload consistency than FTTN

Cause #2  No QoS — Voice Traffic Competing With Everything Else HOW TO DIAGNOSE: Open your router admin page (usually 192.168.1.1 or 192.168.0.1 in a browser). Look for a ‘QoS’ or ‘Quality of Service’ section. If it’s disabled or not configured, that’s your problem. Without QoS, a staff member downloading a large file or joining a video call can consume bandwidth that your phone calls need — causing audio to break up or calls to drop entirely. HOW TO FIX IT: Enable QoS on your router and prioritise traffic by port — VoIP typically uses ports 5060 (SIP) and 10000–20000 (RTP audio)If your router doesn’t support QoS, it may be time to replace it — a business-grade router with QoS support costs $150–$400 and is one of the highest-ROI upgrades for any VoIP officeAlternatively, configure a VLAN (Virtual Local Area Network) to separate voice traffic from data traffic entirely — your IT provider or Broadconnect can assist with thisOn Broadconnect’s hosted PBX, our support team can advise on the exact QoS settings for your router make and model

Cause #3  Wi-Fi Instead of Ethernet for Desk Phones HOW TO DIAGNOSE: Make a test call using the same phone or softphone, but plug directly into your router via ethernet cable instead of using Wi-Fi. If the call quality immediately improves, your problem is wireless interference. Wi-Fi signal degrades through walls, is disrupted by other wireless devices, and introduces latency spikes that VoIP cannot tolerate. A desk phone sitting three offices away from the router on a congested 2.4 GHz network may show ‘connected’ Wi-Fi but have nowhere near enough consistent bandwidth for voice. HOW TO FIX IT: For desk phones: always use ethernet. This is non-negotiable for reliable VoIP. Run a cable or use a powerline ethernet adapter if cabling isn’t possible. For staff using softphones on laptops: connect via ethernet when making calls, or use a USB ethernet adapter. If Wi-Fi calls are unavoidable, switch to 5 GHz Wi-Fi — it’s faster and less congested than 2.4 GHz, though with shorter range. Consider a mesh Wi-Fi system (e.g. Eero, Orbi, or UniFi) if your office has coverage dead spots causing call drops on wireless devices

Cause #4  SIP ALG Enabled on Your Router HOW TO DIAGNOSE: SIP ALG (Application Layer Gateway) is a router feature that was designed to help VoIP calls pass through NAT (Network Address Translation). In practice, it breaks more VoIP calls than it fixes. If your calls cut out after exactly 30 seconds, you experience one-way audio (you can hear the other person but they can’t hear you), or calls drop immediately after connecting — SIP ALG is almost certainly the cause. Check your router admin panel under ‘Advanced’ or ‘NAT’ settings. HOW TO FIX IT: Disable SIP ALG on your router — this is the single most common fix for 30-second call drops and one-way audio in Australian businesses. If you can’t find SIP ALG in your router settings, search your router model + ‘disable SIP ALG’ online — the setting location varies by brand. After disabling, restart your router and test a call — most businesses see immediate improvement. If your internet provider’s modem has SIP ALG enabled and you can’t disable it, placing a separate router in ‘DMZ’ mode can bypass the issue. Broadconnect’s support team can guide you through this remotely — call 1300 880 330 for assisted troubleshooting

Cause #5  NBN Node Congestion During Peak Hours HOW TO DIAGNOSE: Run a speed test at the same time every day for a week — specifically during business hours (9am–12pm and 2pm–5pm). If your speeds are significantly lower during these windows than they are at 7am or 9pm, your NBN node is congested. This is common in dense commercial and residential areas — particularly in inner-city Sydney, Melbourne, and Brisbane CBDs. Consumer NBN plans have no guaranteed speed during peak hours. Business NBN plans include committed information rates and are prioritised over consumer traffic. HOW TO FIX IT: Switch from a consumer NBN plan to a business-grade NBN plan — this alone often resolves peak-hour call quality issues. Broadconnect’s Business NBN plans include priority traffic handling and SLA-backed speed guarantees unavailable on consumer services. If node congestion is severe and persistent, consider upgrading to a dedicated fibre or business ethernet connection — Broadconnect can assess eligibility for your addressAs an interim fix, schedule large file transfers, software updates, and backups outside of business hours to free up bandwidth during calls

Cause #6  Wrong Internet Plan — Consumer NBN Running a Business HOW TO DIAGNOSE: Check your current internet plan. Is it a consumer plan — the kind sold for home streaming and gaming? Consumer NBN plans are ‘best effort’ — meaning your traffic has no priority over anyone else’s. There are no speed guarantees, no SLAs, and in some cases providers explicitly throttle VoIP traffic on residential plans. If your ‘business internet’ is a residential plan with a higher data cap, you’re paying business prices for consumer performance. HOW TO FIX IT: Check whether your plan includes a Committed Information Rate (CIR) — if it doesn’t, it’s a best-effort consumer service. A true business NBN plan includes guaranteed upload and download speeds, SLA-backed fault restoration (typically 4-hour response vs 3-day consumer), and priority QoS for voice traffic. Broadconnect’s Business NBN and hosted PBX work together — our team configures your connection specifically for your call volume. If you’re on FTTN and experiencing persistent issues, ask Broadconnect about eligibility for an NBN FTTP upgrade — NBN Co is progressively upgrading FTTN connections nationally

Cause #7  Outdated or Faulty Hardware HOW TO DIAGNOSE: Test by making a call from a different device — a different handset, a softphone on a laptop, or the Broadconnect mobile app on your phone. If call quality is fine on a different device but bad on the original, the problem is the hardware. Outdated IP phone firmware, a failing ATA (Analog Telephone Adapter), a degraded ethernet cable, or an overheating router can all introduce audio issues that look exactly like a bandwidth or connectivity problem. HOW TO FIX IT: Update firmware on all IP phones — check your phone brand’s support page for the latest version, or contact Broadconnect support for assistance with supported handsets. Replace ethernet cables that are more than 5 years old, kinked, or running near power cables (electromagnetic interference causes audio problems)Test your router’s temperature — if it’s hot to the touch, it may be throttling performance to protect itself; ensure it’s in a ventilated location. If you’re using an ATA (connecting an analogue phone to a VoIP system), consider replacing it with a dedicated IP handset — ATAs are a common source of audio quality issues. Broadconnect supplies and provisions compatible IP handsets — see our hosted PBX options for hardware recommendations

Still Not Fixed After Trying All 7?

If you’ve worked through all seven causes and your calls are still dropping, the issue is almost certainly one of three things:

• Your phone system provider’s infrastructure: Not all hosted PBX providers operate on carrier-grade networks. Consumer-grade VoIP providers running on shared, unmanaged infrastructure will have persistent quality issues that you can’t fix from your end.
• Your NBN connection type is structurally incompatible: FTTN connections with long copper runs can have upload speeds as low as 2–3 Mbps — not enough for multiple simultaneous calls. The fix is upgrading to FTTP, not tweaking router settings.
• A complex network configuration issue: Multi-site offices, VPNs, and advanced firewall rules can create conflicts that require a qualified network engineer to diagnose. This is where Broadconnect’s support team earns its keep.

📞  Get It Diagnosed — Free Broadconnect offers a free VoIP call quality assessment for Australian businesses. Our technical team will remotely assess your connection, router configuration, and phone system setup — and tell you exactly what’s causing the problem. Call 1300 880 330 or visit broadconnect.com.au.

How to Prevent Dropped Calls Going Forward

Once you’ve fixed the immediate issue, these steps will keep your calls clean long-term:

• Run a VoIP speed test quarterly — not just a regular speed test. Tools like ping.canopy.tools or voipsupply.com/speed-test measure latency and jitter, which are more relevant to call quality than raw download speed
• Use a business-grade hosted PBX on a carrier-grade network — Broadconnect’s infrastructure is purpose-built for Australian business voice traffic, not repurposed consumer VoIP
• Ensure your business NBN plan includes SLA-backed speeds and priority voice traffic — not a consumer plan with extra data
• Set up automatic router firmware updates — an outdated router is a persistent, silent cause of VoIP issues
• Keep your call recording and analytics dashboard active — Broadconnect’s hosted PBX includes real-time call quality monitoring so you can see jitter and packet loss before callers complain
• Consider 4G/5G failover — Broadconnect’s failover solution automatically routes calls to mobile if your NBN drops, keeping your lines live during outages

Frequently Asked Questions

Why do VoIP calls cut out after exactly 30 seconds?

Almost always SIP ALG. This router feature was designed to help VoIP calls but in practice breaks the SIP handshake that keeps calls alive. The call connects, the SIP ALG interferes with the session confirmation after 30 seconds, and the system drops the call. Fix: disable SIP ALG in your router’s admin panel. See Cause #4 above.

Why is my business phone fine in the morning but cuts out in the afternoon?

This is peak-hour NBN node congestion — Cause #5. Your local NBN infrastructure is shared between all businesses and homes in your area. During peak usage windows (10am–noon, 2pm–4pm), congestion reduces available bandwidth. The fix is upgrading to a business-grade NBN plan with committed speeds, or scheduling bandwidth-heavy activity outside those windows.

Why can I hear the other person but they can’t hear me?

One-way audio is almost always a NAT or SIP ALG configuration issue — Cause #4. Your voice packets are being sent but blocked or misrouted before they reach the other party. Disabling SIP ALG on your router resolves this in the vast majority of cases. If it persists, your firewall may be blocking the RTP ports (10000–20000) that carry audio.

How much upload speed do I need for VoIP calls?

Each simultaneous VoIP call requires approximately 85–100 Kbps of upload bandwidth. For an office with 10 staff who might be on calls concurrently, you need at least 1 Mbps upload — ideally 2–3 Mbps to allow headroom. For most business NBN plans from Broadconnect, upload speeds of 20–50 Mbps are standard — well above what VoIP requires.

Is VoIP call quality better on FTTP than FTTN?

Yes — significantly. FTTN (Fibre to the Node) uses copper for the last portion of the network run, which degrades upload speed and introduces latency variability depending on how far your office is from the node. FTTP (Fibre to the Premises) delivers consistent upload speeds with very low latency. If you’re on FTTN and experiencing persistent call quality issues, check your eligibility for an FTTP upgrade — NBN Co is progressively rolling these out nationally.

Can Microsoft Teams or Webex calls cut out for the same reasons?

Yes. Microsoft Teams calls and Webex use VoIP technology and are subject to exactly the same causes. If you’re using Microsoft Teams Direct Routing or Webex Calling through Broadconnect and experiencing call quality issues, the same seven causes and fixes apply.

Should I call my phone provider or internet provider when calls drop?

This is exactly why having a single provider for both is an advantage. When you’re with Broadconnect for both your hosted phone system and business internet, there’s no blame game. One call to 1300 880 330 and our team diagnoses both sides of the problem — network and phone system together.

🔧  One Call Fixes Both SidesMost call quality issues are caused by a mismatch between the phone system and the internet connection beneath it. Broadconnect provides both — which means when something goes wrong, one call to our Australian team resolves it. No finger-pointing between your ISP and your phone vendor. No escalation queues. Just a fix. Call 1300 880 330 or visit broadconnect.com.au for a free call quality assessment.

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