Originally Posted by
mduell
Carrier wifi calling (3GPP/IMS) is done over a VPN, so UA can't inspect the traffic. Same reason you can stream video or whatever else is prohibited over a VPN.
They could block connections to the carrier's VPN endpoint for all protocols, but they haven't done so yet.
That's very interesting. I don't know why I didn't think about that, but makes complete sense that is how the call is handled. That's how their femtocells work. I do like that text messages (real ones) work when it's on as well.