It was never been carrier that couldn't do it. It has always been the phone.
No additional antenna needed either to do it.
Not going to even get on the subject of voice lte as that is a long way off from reality.
This company chose to not have this feature.
Sent from my C64 w/Epyx FastLoad cartridge
http://www.anandtech.com/show/6295/...ous-voice-and-lte-or-evdo-svlte-svdo-support-
Long detailed article on why VZ and Sprint and all other CDMA vendors do not get simultaneous voice and data from the iPhone5.
Essentially they did not want to put another radio and antenna in the phone for just CDMA users. They went instead with a configuration that gives them a single hardware version that actually supports more LTE bands, just the baseline software is different between the 3 models (NA GSM, NA & JP CDMA, & EU GSM).
Perhaps when VoLTE is rolled out widely the iPhone6+ will finally support it (only Metro PCS in the US currently supports voice over LTE).