Can't enable VoLTE/ Bouygues Telecom(France)

[david_descamps]

Hello,
I can't enable VoLTE.
Model Name: ROG Phone I (Z01QD / ZS600KL)
Firmware Version: 16.0420.2003.24_0
Rooted or not: Nop
Frequency of Occurrence: every time
Settings is not present in the phone parameters, and when I use the #*#4363#*# the VoLTE settings is grayed and can not be toggled.
I've double checked with my provider, the option has been activated for my line so it should be ok on their side.

[Christine_ASUS]

Hi david.descamps
Thank you for your reply. I just checked with the relevant team, Bouygues Telecom(France) does not support VoLTE in ZS600KL. Sorry for any inconvenience it may caused. 

[david_descamps]

Can I ask why not? Is there some technical limitation that I'm unaware of?
As far as I understood (I am in network and telco field, but not related to mobile networks, so my understanding might be lacking), as both parties are compatible with the norm, it's more a question of being "whitelisted" as compatible by the carrier than anything else. In that case, isn't it Asus' duty to get in contact with said carrier to get them to whitelist your devices?
That being said, knowing a bit how things are done, it can be costly for you to whitelist your devices with carriers and you might not want to whitelist devices that did not really meet with success.

[Christine_ASUS]

Hi david.descamps
Thank you for your asking. The question is not simply about whitelist, it depends on weather the carrier collaborate with the model. For example, Bouygues Telecom(France) supports VoLTE with ZS620KL, yet with neither ZS600KL nor ZS660KL. If you have any concern of VoLTE next time, kindly contact your carrier for further checking.