Yah, WiFi has improved dramatically since the bad old days. The original, and remaining issue, is mainly experienced when using WiFi on a mobile phone or tablet. VoIP was designed before WiFi became widespread. The G.711 CODEC most often used by VoIP works best with stable, hard-wired Ethernet connections. It doesn't have a robust way to handle signal quality issues created by WiFi, such as congestion and signal drop-out, since you can't do enough buffering of the data stream to overcome signal quality issues, without also creating unacceptable delays in the VoIP audio. Fortunately, modern WiFi works great when devices are stationary (e.g. phone sitting still on your desk). When using it with a portable device (smartphone or tablet), moving around and against your head, signal issues may cause call quality degradation, but again, it's much better than it used to be.
