I use a lot of voip services and there's something to be said for the phone companies actually making a competitive product, here.
I suppose one could argue that "HD calling" is technically just VoIP as well.
"HD voice" is exactly VoIP and with few exceptions is only transported over SIP or a SIP-like protocol using the existing RTP negotiation mechanism, which usually ends up selecting 64kbps companded PCM (same as a landline phone). Increasing use of VoLTE, which is essentially an optimized form of SIP designed to "combine" session control features with LTE for lower overhead, has made this pretty common as HD voice support is standard from VoLTE vendors. There was such a thing as HD Voice over 3G using a similar mechanism that leveraged HSPDA but it was never very common, at least in the US.
VoLTE will quickly become the only way to make cellular phone calls in the US which we can expect to make HD Voice pretty universal. Right now it can be spotty when calling between networks, depending on how their peering is set up.
Maybe smartbrick?
Someone made an interesting observation the other day: it used to be that you rented the phone from the telephone company. Those phones never broke. Now that you buy phones, they do. And the moral is: always look for the incentives. Or, put another way: follow the money.
