Its all about the latency/jitter, not raw throughput
You can run a very good SIP data stream over 11MBS all day with no issues. You can run a perfectly good Vonage stream over a 1MBS connection.
The issue is that if you have interference, or people doing things to cause traffic to be real bursty (e.g. watching Netflix), then the problem is that WiFi is a shared medium, so it's not about raw speed, it's about consistency.
Thus if you can create a separate WLAN or VLAN to protect the voice streams, and also over-provision so there is less chance of calls getting hammered. You need to make sure content/ports such as torrents or spotify are locked down.
Realistically, if you have the bandwidth/stability to run streaming video, then voice is the easy part. Voice quality is not your concern, but if the LAN is too bursty then calls will drop.
