Is One Plus 3T 4G VoLTE enabled phone?

The OnePlus 3T does support 4G LTE, but its support for Voice over LTE (VoLTE) is not universal and depends on the region and carrier.

For the US version, it is indicated that VoLTE is not natively supported. Users in regions where VoLTE is not supported may need to use alternative apps, such as Jio4GVoice, to make voice calls over 4G networks2.

However, in other regions or with specific carriers, the OnePlus 3T might be compatible with VoLTE, but this would need to be verified with the carrier directly.

In summary, while the OnePlus 3T supports 4G LTE, its VoLTE capability is not guaranteed and varies by region and carrier.