Making enterprise voice-over-Wi-Fi systems comply with emergency call regulations requires shoehorning new techniques into a very old architecture. It also exposes some unfinished technology and fragmented implementation models. We can do it, but no one is happy with the contortions.
There’s a large population of enterprise unified communications (UC) systems from Microsoft, Cisco, Avaya, Shoretel and others using Wi-Fi endpoints, whether dedicated Wi-Fi phones or client apps on smartphones. When it comes to emergency call functionality, we should expect these to work at least as well as landlines, PBX extensions and cell phones.
One of the most important emergency call (E911) functions is locating the caller. To make emergency call location work, we first need to find the location, then send the call, with caller location attached, to the correct emergency answering center in a form it can understand. Both of those steps present problems.