At some point it is true.

Stable Update will be available on end of July. But can,t say  that we will get  Volte in first stable update or not. and also it depending on your device.
as i heard:
"Only those devices get volte which are released after 2015"
My m2 note was released in 2015. If above statement is true. then i can,t get Volte.

Phones which come with volte in past like m5, m3s etc will get update but phones which didn't get preloded volte will not get it that fast.
I am meizu m2 user and want to switch to jio but i can't because of volte