Tech Tips Blog

Know the Relationship Between QoS and Voice Over Wi-Fi

Packet drops and jitter can greatly reduce the quality of a Voice Over Wi-Fi call. When troubleshooting Voice Over Wi-Fi call quality issues the following items should be looked at.
i. QoS Configuration
ii. Latency
iii. Jitter
iv. Signal Strength
v. SNR
vi. Roaming
vii. Packet Loss
A simple ping test can be used to exam the latency. The latency should not exceed 150ms, ideally it should be much less. Also, the latency should be consistent; as to not introduce jitter or variance in the latency (jitter should be less than 30ms).
You should also validate signal strength, which should be -67dBm or stronger; and you should have an SNR higher than 25dBm. Last, but not least packet loss should be less than 1%.
A Wi-Fi network analyzer can also be used to greatly reduce the amount of time troubleshooting such issues. For example, a Wi-Fi Analysis test can be used to gather all the stats along with ping times from the two end points in one simple test.