Telecoms glossary • P
Packet loss
The single most common reason business calls sound broken up – and usually the cheapest to fix.
What is packet loss?in VoIP and business telephony
1. Data that leaves one end of a call and never arrives at the other. Voice is split into small packets; when some go missing you hear gaps, clipped words or robotic audio.
2. Unlike a web page, a call cannot wait for a lost packet to be re-sent. Anything lost is simply gone, which is why voice tolerates far less loss than ordinary internet traffic.
How much packet loss is too much
Cisco’s long-standing quality-of-service guidance sets the bar for acceptable voice at under 1% loss, alongside 150 ms of one-way latency and 30 ms of jitter. Those three numbers are the industry yardstick, and any provider offering an SLA should be willing to discuss all three rather than quoting a single uptime figure.
The percentages matter less than the pattern. Steady low-level loss across a whole day points at the line; loss that spikes at 09:00 and 14:00 points at congestion inside your own office.
What causes it
Four causes account for nearly every case in South African offices.
- Congestion
- More traffic than the line carries. A cloud backup or a large upload running in business hours is the classic culprit, and by far the most common cause.
- Wi-Fi
- Wireless is inherently lossier than cable. Distance, walls and competing networks all surface as dropped audio.
- Faulty hardware
- A damaged patch lead, a dying switch port or an overheating router. Cheap to find, cheap to fix, routinely overlooked.
- Upstream faults
- Congested links or poor peering at your ISP. Outside your control, but provable with a sustained test.
Finding it before you phone anyone
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Test on cable, not Wi-Fi
Plug a laptop directly into the router and repeat the call. If the loss disappears, the fault is your wireless network and no provider can fix it for you.
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Test across a full day
A one-off speed test proves nothing. Sustained testing exposes the congestion pattern.
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Prioritise voice with QoS
Configure QoS so voice packets go first. This alone resolves most congestion-driven loss.
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Swap the cheap parts
Replace patch leads and move to a different switch port before escalating anywhere.
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Escalate with evidence
Loss persisting on cable with QoS enabled is an upstream fault. Give your ISP the test window and the percentage, not an adjective.
Quick diagnosis
Choppy audio in both directions is usually packet loss. Audio in one direction only is almost always NAT or a firewall. A delay that makes you talk over each other is latency, not loss.
Knowing which of the three you have is the difference between a five-minute fix and a support call that opens with someone asking you to reboot the router.
About this entry
Definitions are written for South African business buyers and checked against primary sources – provider documentation, standards bodies and ICASA – not vendor marketing. Reviews are independent and sponsors are always disclosed. Read our editorial policy and scoring methodology.
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