While I lament the loss of functionality on my own 950XL on AT&T, I do not agree that it is odd or wrong of MS in any way to advertise functionality that the phone is perfectly capable of performing. I do however think that AT&T's policies towards BYOD leans towards the class action lawsuit side of things and should be reviewed by the FCC.
The phone is carrier unbranded and these features are carrier specific. From Microsoft's standpoint they included the functionality and thus can advertise it as such. It is not their fault that AT&T are asshats when it comes to supporting unbranded devices. I have heard of people with the 950XL in other countries using VoLTE and/or Wifi calling on their carriers with no problems.
It's not just AT&T though, it's pretty much any carrier (in the US), T-Mobile is saying the same, they're claiming MS never completed "certification" with them.
I don't think you'll hear of any others with a dual-SIM Win10m phone using VoLTE, I think this isn't finished, on the MS side, but I could be wrong.
Does anyone know for sure this works with a dual-SIM Win Phone? I know I saw someone post about it NOT working, in India.
I agree, that somehow the carriers (mostly AT&T here) need some "leverage" to get behind this, particularly since they're trending towards LTE-only implementations moving forward, so without VoLTE, you might have a really strong signal, but not voice capability.
This is sort of the way it is at my house, I have screaming fast data on Band 17, but my voice (I think it's band 4, I'd have to go back and check) is really iffy, drops all the time, etc. If I had VoLTE, or WiFi Calling, I would have voice just fine.
Does anyone want to start an FCC complaint? I'm a bit tenuous, because I work on the AT&T forums, as one of their MVP types, so I have to "tread a bit carefully".
I agree, I'm pretty "annoyed" with their policy, they always say "branded only" but then run and hide if I mention the iOS thing, apparently they don't want to discuss that, because it's completely outside of the model.