Glossary Call quality
What is Packet loss?
Also called dropped packets, lost packets
Packet loss is what it sounds like: some packets never arrive. In file transfer they are simply re-sent and nobody notices. In a live call there is no time to re-send, so the missing audio is gone, and the receiver conceals the gap as best it can. The result is dropped syllables, clicks or brief silences.
How much matters
Voice tolerates a surprising amount because concealment algorithms are good at guessing what was missing. Under about 1% is usually imperceptible. Between 1% and 3% is audible as occasional roughness. Above 5% the call becomes hard work. Loss that comes in bursts is far worse than the same percentage spread evenly, because concealment can bridge one missing packet but not ten in a row.
Finding the cause
Loss on a voice call is rarely the internet at large. The usual suspects are the local network: a saturated uplink, a failing cable or port, wifi with poor coverage, or an underpowered firewall doing deep inspection on every packet. Testing from a wired connection is the quickest way to rule wifi in or out.
Loss upstream and downstream are different problems
Determining which direction is losing packets narrows the search enormously. Loss on your outbound is usually your own uplink or equipment, and is something you can act on directly. Loss on the inbound is upstream of you, and is a conversation with your provider. Most VoIP platforms report both directions per call, so the first diagnostic step is to look at which one is actually degraded rather than treating "packet loss" as a single undifferentiated symptom.