Perhaps a bit of a strange title but I recently attended an event that had excellent LTE/5G coverage outside buildings, and good Wi-Fi coverage mainly inside buildings. In other words: A good opportunity to have a look at how well an ongoing IMS voice call is switched between LTE (VoLTE) and Wi-Fi (VoWifi) these days.
While early VoWifi implementations quite a number of years ago only kicked-in when no cellular was available anymore, it looks like algorithms and ‘opinions’ on how to do the transition between Wi-Fi and LTE (and 2G) have advanced quite a bit. In practice, most devices these days are looking at both LTE and Wi-Fi signal strength and perhaps other parameters like packet error rate to decide when to switch an ongoing IMS call between VoLTE and VoWifi.
Back to practice and it was nice that the device at hand was hopping in both directions, i.e. from LTE to Wi-Fi and back to LTE while voice quality was still good. In fact, I didn’t notice any outage of the speech path, the experience was really smooth. I’m impressed!