Yes for some odd reason both Vodafone and O2 do voice only over WiFi. Must be something to do with the age of either their core or billing systems!

Yes EE has their settings in Samsung generic firmware.

In reply to a post by Oliver341:

O2 is a little tedious in that they allow wi-fi calling but only on pay monthly.

Also texting doesn't work on O2 when connected to WiFi calling for some reason. Other networks it works fine.

As above both Vodafone and O2 implemented only calling over WiFi no texting.

This is a bit short sighted now the government has directed banks and finance companies to do two factor logon codes for internet shopping and banking.

Wifi calling were made to improve their customer support. Before Idea or Vodafone Wifi calling services began their testing and their rollout to the masses. The merger happened. Even in 2020, where others have already offered their Wifi calling service to users and trying to add newer devices and telecom circles to their coverage list. Vodafone Wifi calling has not made any groundbreaking revelations. Vodafone users are eagerly waiting for Vodafone to begin testing and rolling out the Vodafone Wifi calling in India so that they can stay on par with the competition by others.

That may be true for India but the rest of comments are for the U.K. network.

Just waiting on the spam to appear

I can use wifi calling on plusnet on my iphone my wife is on o2 and she can't on her iphone,option doesn't even show on hers,so we know the iphone can this means it's combination of phone type and nework that both matter,she is stubburn and won't switch networks because "when we visit my mum mine is only phone tha gets a signal"!:-its onl place her phone her phone works and mine doesn't,loads of places the opposite applies,don't get her logic/reasoning

O2 supports wi-fi calling but not on pay as you go. She could move to a contract and stay on O2.

both use sim only,don't want tying to a contract for at least 12 months,O2 is slow data wise as well and expensive compared to others for what you get