NTT Docomo announced today that VoLTE is planned to start in late June. Currently, even for LTE phones, voice is transmitted over the old W-CDMA (3G) network. I'm most interested in how VoLTE from NTT Docomo will affect voice pricing for MVNOs. I believe there is expectations that this will lower wholesale costs.
With VoLTE, audio quality should be improved, due to higher bandwidth (50Hz – 7kHz), which should allow for the use of a better codec. Compared to existing LTE phones, calls should connect faster (since there is no switching to 3G). VoLTE phones can also receive area mail alerts (like the earthquake warnings) while a call is connected. With all the free chat options now available, I doubt it matters any more, but the video calling with also have improved quality over the existing FOMA terebi denwa.
The price plan will include the "kake-houdai" Unlimited Calling announced recently, which is ¥2,700. At launch, four phones will be supported (through software updates). These are:
- GALAXY S5 SC-04F
- Xperiz Z2 SO-03F
- AQUOS ZETA SH-04F
- ARROWS NX F-05F
Sometime after July, updates will come to two tablets (AQUOS PAD SH-06F and the Xperia Z2 Tablet) that will enable VoLTE.
Now that the summer line up has been announced, I would recommend that you don't immediately look for a way to flash a custom OS onto your new phone, as you won't be able to receive the update to enable VoLTE.