Environment : This article list out the settings for a voice SSID in Instant AP deployments.
As per International Telegraph Union Telecommunication (ITU-T) recommendation, there should be less than 150 millisecond (ms) one-way end-to-end delay for high-quality real-time traffic such as voice.
As a packet traverses the network from source to destination, congestion in the network can result in the packet getting dropped, delayed and/or corrupted, resulting in retries and lost packets. The packets may also arrive at the destination with varying delays (jitter) or out of sequence. All of these problems adversely affect the quality of real-time traffic like voice and video.
Below screenshot show the recommended setting in SSID advanced options in Instant AP deployments:
Disable 1 and 2 mbps in Transmit rates.
Enable "Broadcast filtering" as "ALL" for Data SSID. This would increase airtime for voice clients
Max clients threshold is left blank, as it would depend on the model of Instant AP and how good is the RF coverage.