How jitter occurs
Data packets travel across the network via different routes and pass through nodes with varying levels of congestion. Every router or switch that processes them adds a short delay. If this delay is not constant but fluctuates, jitter occurs.
Most common causes of jitter:
- Overloading of network equipment during peak data transmission.
- Unstable Wi-Fi connection with fluctuating signal strength.
- Shared internet connection without configured voice traffic priority (QoS).
- Inappropriate network configuration or outdated network hardware.
How jitter affects business calls
The human ear is sensitive to fluctuations in latency. When jitter exceeds approximately 30-40 ms, calls become unpleasant: the voice may crack or parts of sentences drop out. At higher values, the call becomes unintelligible.
Software VoIP clients and IP telephones feature a so-called jitter buffer (a memory for equalising voice packets). This memory temporarily holds received packets and releases them in the correct order and rhythm. The jitter buffer compensates for network instability to a certain extent, but an excessively large buffer adds latency. Manufacturers therefore set a compromise between jitter compensation and added delay.
How to measure and reduce jitter
Jitter is measured using the ping tool with repeated measurements, variations in response times indicate how much the network fluctuates. There are also specialised tools for measuring VoIP quality that clearly display jitter, latency and packet loss.
To reduce jitter, these measures help:
- QoS settings on the router: voice packets are given priority and wait less in the queue.
- Switching from Wi-Fi to wired Ethernet connections at critical workstations.
- Upgrade the router or switch if they are outdated and cannot handle the traffic load.
- Segregating voice devices into a separate VLAN.
The cloud-based PBX resolves jitter on the provider's side internally. The key is to ensure a stable network on your end, when setting up at virtualni-ustredna.cz, you will receive specific recommendations for this purpose.
Frequently Asked Questions
What jitter value is acceptable for VoIP?
The recommended jitter value for VoIP calls is below 30 ms. Values up to 50 ms are generally still tolerable. Above 50 ms, crackling and word dropouts begin to become significantly noticeable.
How do I measure jitter on my connection?
Perform a basic test using the ping tool with a higher number of repetitions, observe how much the response times vary. More accurate results are provided by specialised tools for measuring VoIP quality, such as PingPlotter or the built-in monitoring in the cloud PBX.
Can jitter cause a complete call drop?
Yes. If jitter is so high that the jitter buffer cannot compensate for incoming packet instability, some voice data will be lost or arrive late. At extreme values, the call will break up or the system will disconnect.