O2 really need to get ahead of the curve with new tech. They had a very good app called TU GO which worked as a VoIP phone, letting you send/receive texts and make/receive phone calls through wifi. Great, until they got rid of it and replaced it with WiFi calling, which is built into most modern handsets. At least I thought it was great until I moved house to somewhere where there is absolutely no mobile signal on any network.
I thought "wifi calling will cover me". Well, sort of. Calls work fine, but SMS is not carried over the wifi bearer for some reason! My wife's EE phone can do it, but not O2. Trying to get an answer out of them elicits the telephonic equivalent of a blank stare. They have no clue when or if it'll work. But WHY? Why doesn't it work? Why can't they make it work like other networks do?