You might have seen in many blogs which says lineage os supports volte in OnePlus one(opo). They have published a false post because, in lineage os website they have mentioned they would provide lineage os which would support volte. They have announced this as a news item on April 1. But it was just a prank. They said April fool to us. So lineage os won’t give volte support. They have also said that only OEM can give you such an update. You may have a doubt what is OEM. It is nothing but Original equipment manufacturer.
Now I’m using OnePlus One with lineage os. Unfortunately I was filled by them. Any how they have given nougat version and I love this custom ROM. I’m missing some CM14 features. Especially in customising the theme but feeling this fresh OS is satisfactory.
Final note: if you have OnePlus One and still waiting for volte support. I’m sorry for you.