Ahhh! He is on O2. I might take one of my spare Three SIMs along when I can go over in the near future. Thanks .
Three was the first to enable WiFi calling (and 4G calling) for PAYG users. I am informed that Vodafone PAYG mostly works now, but EE and O2 may only today be for contract users (including 30day sim only)
O2 is unfortunately the slowest network to update to these technologies. It appears Three are the early adopters, EE are steady and fast moving, Vodafone is trying to get into the same state as EE, and O2 is bringing up the rear.
What I don't quite understand is how it works for incoming calls. Or doesn't it? Just bi-directional over the net when instigated by him.
Its an IPsec connection from the handset to the network. Calls work both ways as the handset keeps the link open (solves the inbound NAT complexity). Don't do as I did and turn off "IPsec PassThru" in my Asus router and wonder why WiFi calling wasn't working. not many routers have that option.
Edit! It's a contract though, not PAYG.
Then it could depend on the handset. Three and EE support more handsets than the other two today, but this is changing fast as Android upgrades.
Edit2: Makes sense in a way. Letting a PAYG SIM use the home router for calls rather screws the business model of PAYG.
nope, you STILL pay from credit, or bundle, when using WiFi calling. It literally replaces the signal, the billing is identical to using the macro network.
Think of WiFi calling as a Femto Cell built into your handset (e.g. Vodafone SureSignal).
I can see a lot of this changing by the end of 2021 as 3G gets reduced and withdrawn in favour of 4G on the same frequencies.
21 years of broadband connectivity since 1999 trial - Live BQM