Could you possibly help how to identify VoLTE capable devices based on UE Capability Information. As far as I know FGI bit 3,7 and 27 should be set to 1. Is there 100% working way to detect VoLTE caabilities of the UE? Can be UE usage and Voice domain preferences used for this?
Why many LTE handset don’t support VoLTE?
Is it hardware or software that causes the restriction?
Could you pls elaborate it a little?
It’s just a manufacturer decision based on his costs and marketing strategy to integrate or no VoLTE flagship into his devices
Not mandatory since many countries are still not using VoLTE.
Simply Hardware limitations on handsets side.
Whether is it also possible that a handset may support only particular band VoLTE not all?
Same as LTE band support.
No, VoLTE support is not really limited by LTE bands.
For 4G handsets, VoLTE is mostly limited by the whitelist in the handset software. If your PLMN is not in the whitelist of the handset, then VoLTE capable handset attached to 4G on your network will still refuse to use VoLTE with your network. And make no mistake, the whitelist is short.
However, it does seem that there is hope with Apple. With updated iOS and iPhone 7 and higher, the user can actually enable VoLTE in the settings - even if the PLMN of the network is not in the handset whitelist.
I am searching for a reliable source for VoLTE capable handsets.
As I said above, most VoLTE capable headsets are operating with a whitelist.
If your PLMN is not in the whitelist, then the “VoLTE capable headset” will not attach for VoLTE on your network.
The situation is that most 4G headsets support VoLTE. But most mobile networks are not in their whitelist…
If any mobile or UE don’t have Volte it can be functioned by updating a firmware in mobile and set some details of networks like PLMN(MCC and MNC), modem, Apn Name, APN Type, Apn protocol and have to write volte.