My wife has a sim-free Sony Xperia 5IV with a Vodafone sim-card (bear with me). Vodafone are currently closing their 3G network & are saying that the phone isn't compatible with VoLTE. I have put my o2 sim-card in her phone & its works fine, VoLTE appears in the settings (my phone is also sim-free). Her account has VoLTE enabled, so it would appear that the sim-card is disabling VoLTE.
If an o2 sim-card was purchased, would this then enable VoLTE or are o2 also now restricting it to purchases through o2.
