When VoIP is set up properly, calls are clearer than the old copper lines ever were. When it isn’t, you get the classics: robotic voices, echo, one-way audio, drops. The encouraging truth is that almost every VoIP quality problem traces back to a short list of causes — and most have straightforward fixes. Here’s the troubleshooting guide we wish every business had.
The four usual suspects
- Not enough upload headroom — voice needs upload as much as download. If big uploads, cloud backups or video calls are saturating the line, voice packets queue behind them and calls break up.
- Jitter — variation in packet arrival times. The network delivers voice unevenly and words smear or stutter. Congested Wi-Fi and overloaded routers are the usual sources.
- Latency — long delay makes conversations feel like a satellite interview, with people talking over each other.
- Packet loss — bits of the conversation simply never arrive; you hear gaps or robotic artefacts.
Symptom → likely cause
- Choppy or robotic audio → packet loss or jitter — look at Wi-Fi, congestion, or a struggling router.
- Echo → usually a handset/headset issue — speakerphone volume too high, or a cheap headset; rarely the network.
- One-way audio → almost always a router/firewall configuration issue, not your broadband.
- Calls dropping → an unstable connection or a router rebooting/misbehaving under load.
- Bad only at certain times → congestion — something else is flooding the line at those moments (backups are a classic 6pm culprit).
Fixes, in the order to try them
- 1. Wire the important phones. Desk phones on Ethernet remove Wi-Fi from the equation entirely — the single most effective fix.
- 2. Turn on QoS. Most routers can prioritise voice traffic so calls always go first, even during heavy use. This is the setting that fixes “calls die when someone uploads”.
- 3. Sort the Wi-Fi you keep. For softphone users, decent coverage where they sit matters — a laptop three walls from the router will produce complaints no phone system can fix.
- 4. Look at the router itself. Some ISP-supplied routers handle voice poorly or apply “helpful” features (like SIP ALG) that actively break calls. A settings change or better router often transforms quality.
- 5. Schedule the heavy stuff. Push backups and big syncs outside hours so they never fight the phones.
- 6. Measure before blaming the broadband. A proper test of latency, jitter and loss tells you whether the line is the problem or the network inside the building is. They’re fixed in different places.
Connection choice matters too — our guides cover what to expect on fibre, 5G broadband and Starlink.
When it’s not the network at all
Worth checking before deeper surgery: worn headsets, phones on old firmware, a handset with a failing cable, or one user’s laptop drowning in background apps. If exactly one person has bad calls, start at their desk, not the router.
Frequently asked questions
How much bandwidth does a VoIP call need?
Around 0.1 Mbps in each direction — tiny. Quality problems are almost never about total speed; they’re about stability and what else is hogging the line at that moment.
Why are calls fine in the morning and awful at 4pm?
That pattern is congestion — something (often backups or big transfers) is loading the connection at those times. QoS plus scheduling heavy jobs usually cures it.
Can bad Wi-Fi really ruin VoIP?
Yes — Wi-Fi is the most common source of jitter indoors. Wire the desk phones and the difference is usually immediate.
Prefer it just fixed?
This is bread-and-butter work for us: we test the line, tune the router, wire what should be wired and set QoS so calls stay clear under load. Ask Bellcom to look at your setup — local, practical, no jargon.