|To really solve these VoIP problem, Wi-Fi systems must be able to constantly choose transmission paths between the AP and voice device that deliver the strongest signal, fewest delays and lowest packet error rates, while simultaneously attenuating any interference or noise.
David Callisch, Minding the VoIP…
Wi-Fi Multimedia (WMM) is four traffic queues (voice, video, data and background) that are shared among all users. The problem is if one VoFi device is lost (for whatever reason) the AP typically retransmits to that device before servicing other devices. The solution is to have a wireless LAN system that uses a per-client, per-traffic class QoS scheme so every client and traffic flow is fairly serviced.